Retigabin 2025-09-26 11:22:57

Retigabin clinical use in neuropathic pain

Retigabine in the Clinical Management of Neuropathic Pain: A Scientific Overview

1. Introduction

Neuropathic pain is a complex, chronic pain state resulting from injury or dysfunction in the nervous system. First-line treatments typically include tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and gabapentinoids, as supported by multiple national and international guidelines (A Comprehensive Algorithm for Management of Neuropathic Pain - PMC, 2019). However, a significant proportion of patients experience insufficient pain relief or intolerable side effects, prompting ongoing research into alternative pharmacotherapies such as retigabine.

Retigabine (also known as ezogabine), originally developed as an anticonvulsant, is notable for its novel mechanism of action via activation of neuronal KCNQ (Kv7) potassium channels. This review synthesizes available evidence on retigabine's clinical use in neuropathic pain, focusing on preclinical data, clinical trials, efficacy, safety, and its current place in therapy.

2. Mechanism of Action and Preclinical Evidence

2.1 Mechanism of Action

Retigabine acts as a neuronal KCNQ/Kv7 potassium channel opener, specifically targeting Kv7.2–Kv7.5 subtypes. These channels are responsible for the M-current, a subthreshold potassium current that stabilizes the resting membrane potential and dampens neuronal excitability. By enhancing the M-current, retigabine reduces the likelihood of aberrant action potential generation, a hallmark of neuropathic pain states (Blackburn-Munro et al., 2005).

2.2 Preclinical Data

A robust body of animal research demonstrates that retigabine dose-dependently attenuates pain-like behaviors (hyperalgesia and allodynia) in rodent models of persistent and neuropathic pain (Blackburn-Munro & Jensen, 2003). These effects are attributed to the drug's ability to stabilize neuronal membrane potentials and suppress abnormal excitability in pain pathways.

Notably, retigabine's analgesic efficacy in animal models was found to be broad-spectrum, reducing both acute and chronic pain-like behaviors (Blackburn-Munro et al., 2005). This provided a strong rationale for clinical investigation in neuropathic pain conditions.

3. Clinical Trials and Efficacy in Neuropathic Pain

3.1 Human Studies

Despite promising preclinical results, the translation of retigabine’s analgesic properties to clinical neuropathic pain populations has been limited and ultimately inconclusive. A Phase II randomized, placebo-controlled trial was conducted to assess the efficacy of retigabine in patients with postherpetic neuralgia, a canonical model of neuropathic pain (Retigabine - Wikipedia).

Key Findings:
- The Phase II trial failed to meet its primary endpoint—retigabine did not demonstrate statistically significant pain relief over placebo.
- Valeant Pharmaceuticals, the study sponsor, described the preliminary results as "inconclusive," and no subsequent Phase III program was initiated.

Thus, while animal data suggested a potentially valuable role for retigabine in neuropathic pain, clinical evidence of efficacy is lacking (Retigabine - Wikipedia).

3.2 Comparison with Other Anticonvulsants

Other antiepileptic drugs (e.g., gabapentin, pregabalin) have shown moderate efficacy in neuropathic pain, with Number Needed to Treat (NNT) values of 6.3–8.3 for gabapentin and 7.7 for pregabalin, and established safety profiles (A Comprehensive Algorithm for Management of Neuropathic Pain - PMC, 2019). In contrast, retigabine did not demonstrate sufficient efficacy in human neuropathic pain trials to warrant its adoption or inclusion in guidelines.

4. Safety and Tolerability

4.1 Adverse Effects

Retigabine’s adverse effect profile was characterized in epilepsy trials and included:
- Central nervous system effects: drowsiness, dizziness, confusion, slurred speech, tremor, gait disturbances, memory loss, and double vision.
- Unique side effects: blue skin discoloration and retinal pigment changes, with uncertain reversibility (Retigabine - Wikipedia).
- Psychiatric symptoms and urinary retention (notably, the risk of bladder dysfunction prompted specific FDA safety monitoring recommendations).

These side effects, while generally dose-related and reversible, contributed to limited enthusiasm for broader clinical use.

4.2 Regulatory Status

Retigabine was approved by the FDA and EMA for adjunctive treatment of partial-onset seizures in adults, but was withdrawn from the market in 2017 due to commercial reasons and concerns over long-term safety (notably, pigment changes) (Retigabine - Wikipedia).

5. Current Clinical Role

5.1 Guidelines and Recommendations

Current consensus guidelines and comprehensive treatment algorithms for neuropathic pain do not include retigabine as a recommended therapy (A Comprehensive Algorithm for Management of Neuropathic Pain - PMC, 2019). Instead, first-line pharmacotherapies are gabapentinoids, SNRIs, and TCAs, with second- and third-line options including tramadol, tapentadol, and other anticonvulsants (e.g., carbamazepine, lamotrigine) with more substantial clinical evidence.

5.2 Rationale for Exclusion

The absence of clear, positive evidence from controlled clinical trials in neuropathic pain, combined with the potential for significant adverse effects and subsequent market withdrawal, precludes retigabine from current practice.

6. Summary and Future Directions

Mechanistic Rationale: Retigabine’s action as a KCNQ/Kv7 channel opener provides a compelling mechanistic rationale for use in neuropathic pain, corroborated by strong preclinical evidence (Blackburn-Munro & Jensen, 2003).
Clinical Efficacy: Human studies failed to show significant benefit in neuropathic pain, and no regulatory approval was sought for this indication (Retigabine - Wikipedia).
Safety: Adverse effects, particularly pigment changes and CNS symptoms, limit its clinical utility.
Guidelines: Not recommended in current neuropathic pain management algorithms due to lack of efficacy and safety concerns (A Comprehensive Algorithm for Management of Neuropathic Pain - PMC, 2019).

6.1 Research Implications

While retigabine itself is unlikely to be revisited as a therapy for neuropathic pain, its mechanism has inspired the search for newer, better-tolerated Kv7 channel modulators. Future research may yield agents that harness this mechanism without the liabilities of retigabine.

References

Conclusion

Retigabine represents an important step in the pharmacological exploration of potassium channel openers for neuropathic pain. Despite promising preclinical data, retigabine’s clinical utility in neuropathic pain remains unproven, and its use is not supported by current evidence or guidelines. Ongoing research into this class of drugs may yet yield viable options for patients with refractory neuropathic pain.

REFERENCES

ClinicalTrials.gov - last accessed: 2025-09-26

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Sources used

QUERY: Retigabine AND "neuropathic pain" AND clinical use

Neuropathic pain and Kv7 voltage-gated potassium channels: The potential role of Kv7 activators in the treatment of neuropathic pain.
Molecular pain. 2019/7/26; Impact Factor: 3.21, Quartile: Q1
DOI: 10.1177/1744806919864256
PMID: 31342847
Abstract
Neuropathic pain conditions severely and chronically affect the quality of life in a large human population, but the pain conditions are not adequately managed due to poor understanding of their underlying mechanisms. There is a pressing need for further research into this field to help develop effective and nonaddictive medications to treat neuropathic pain. This article first describes general clinical classification of pain, types and symptoms of neuropathic pain, and current practices of clinical management for neuropathic pain. This is followed by a discussion of various cellular and molecular mechanisms responsible for the development and maintenance of neuropathic pain. In this review, we highlight the loss of function of Kv7 voltage-gated potassium as a mechanism of neuropathic pain and the potential use of Kv7 channel activator as subsequent treatment.

QUERY: Retigabine OR ezogabine AND "neuropathic pain" AND efficacy

Antinociceptive Efficacy of Retigabine in the Monosodium Lodoacetate Rat Model for Osteoarthritis Pain.
Pharmacology. 2014/11/18; Impact Factor: 2.84, Quartile: Q2
DOI: 10.1159/000381721
PMID: 25997526
Abstract
The goal of pharmacological osteoarthritis (OA) treatments is to reduce pain and thus increase patient joint function and quality of life. Retigabine, a potent Kv7/M channel activator, shows analgesic efficacy in animal models of chronic inflammatory and neuropathic pain. We hypothesized that retigabine may also mitigate OA pain. To determine the effects of retigabine on pain behavior associated with monosodium iodoacetate (MIA)-induced OA.
The OA model was established with an intra-articular injection of MIA through the right patellar ligament, animals were treated with retigabine, and pain-related behaviors were assessed.
Retigabine significantly increased the mechanical threshold and prolonged the withdrawal latency of OA rats at 3-14 days. Retigabine also increased the mechanical threshold and prolonged the withdrawal latency of OA pain in a dose-dependent manner, with the strongest antinociceptive effect occurring at 60 min. The antinociceptive effects of retigabine were fully antagonized by the Kv7/M channel blocker XE991.
Retigabine showed antinociceptive effects for OA pain in the MIA model at different times during pain development. Retigabine may be an alternative therapeutic treatment for OA.

QUERY: Retigabine AND "neuropathic pain" AND (treatment OR therapy))

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

� systematic review of pharmacologic management of chronic neuropathic pain [ 2 ] calculated that the combined NNT 1 of 14 RCTs of gabapentin was 6.3 (5.0–8.3). Similarly, the combined NNT from six RCTs of gabapentin extended-release/encarbil was 8.3 (6.2–13). The NNH 2 for gabapentin for all etiologies combined was 25.6 (15.3–78.6) [ 2 ]. Finnerup et al. also assessed the efficacy of pregabalin. The combined NNT of 25 RCTs was 7.7 (6.5–9.4), and the NNH was 13.9 (11.6–17.4). Unlike gabapentin, they also reported a dose response, with a greater response being seen in those taking 600 mg daily than in those taking 300 mg [ 2 ]. Pregabalin has also been shown to decrease health care and non–health care costs compared with gabapentin in the treatment of peripheral neuropathic pain [ 61–63 ]. Gabapentanoids should be trialed for a four- to six-week period with two weeks at the maximum tolerated dose [ 10 , 13 ]. Poorly tolerated side effects or inadequate pain relief should prompt dosage adjustment, cessation of the medication, progression to other firstline agents, or a trial of combination therapy. The most common adverse effects include somnolence, fatigue, dizziness, and lower extremity edema [ 60 ]. Topical—Lidocaine, Capsaicin, and Transdermal Substances The side effect profile of TCAs, SNRIs, and gabapentanoids requires extremely cautious dosing in many patients, especially the elderly, with some patients having side effects with the lowest available doses. As an alternative, topical medications are supported by multiple guidelines, but where they fit into the algorithm varies from firstline to not at all [ 2 , 3 , 8 , 13 , 14 ]. The topical preparations referred to in guidelines are limited to lidocaine patches and capsaicin. However, there is some evidence on other topical antineuropathics that may provide a practical solution in some patients who are intolerant, or in whom it is unsafe to use oral medications. Lidocaine. Topical lidocaine works by decreasing

Retigabine: Chemical Synthesis to Clinical Application - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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Retigabine: Chemical Synthesis to Clinical Application - PMC

pain transmission. Although sometimes difficult to treat with conventional analgesics, antiepileptics can relieve some symptoms of neuropathic pain. A number of recent studies have reported that retigabine can relieve pain‐like behaviors (hyperalgesia and allodynia) in animal models of neuropathic pain. Neuronal activation within several key structures within the CNS can also be observed in various animal models of anxiety. Moreover, amygdala‐kindled rats, which have a lowered threshold for neuronal activation, also display enhanced anxiety‐like responses. Retigabine dose‐dependently reduces unconditioned anxiety‐like behaviors when assessed in the mouse marble burying test and zero maze. Early clinical studies have indicated that retigabine is rapidly absorbed and distributed, and is resistant to first pass metabolism. Tolerability is good in humans when titrated up to its therapeutic dose range (600‐1200 mg/day). No tolerance, dependence or withdrawal potential has been reported, although adverse effects can include mild dizziness, headache, nausea and somnolence. Thus, retigabine may prove to be useful in the treatment of a diverse range of disease states in which neuronal hyperexcitability is a common underlying factor. Keywords: Anxiety, Epilepsy, KCNQ – K V 7 channel, M‐current, Pain Full Text The Full Text of this article is available as a PDF (166.7 KB). REFERENCES 1. Adamec RE,
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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

ically significant changes of greater than two points on a VAS scale were seen immediately post-treatment, but only 49% of patients maintained this level of pain reduction at three-month follow-up. The average pain relief at this time was 1.3 on a 10-point numeric pain scale. Similarly, early gains in depression were lost by three months, whereas the significant gains in catastrophizing and pain acceptance were maintained [ 45 ]. If trialed alone without pharmacological or interventional strategies, it is recommended that these are limited to a duration of six to eight weeks. If adequate pain relief is not achieved within this time, firstline medications should be initiated. Neuropathic pain and its physical, psychological, and social consequences for the patient are variable throughout the course of the condition. At any point in the treatment protocol, the above conservative measures should be utilized to manage any ongoing concerns or new issues arising secondary to the pain. Pharmacological Management Medications form the basis of first- and second-line therapy for neuropathic pain ( Table 1 ). Tricyclic antidepressants (TCAs), serotonin norepinephrine reuptake inhibitors (SNRIs), gabapentanoids, tramadol, lidocaine, and capsaicin are the most effective options [ 1–3 , 8 , 9 , 13 , 14 ]. Most of these first- and second-line options come with considerable potential for side effects. Depending on the medication, a three- to eight-week trial is recommended with review midway and at the end of the trial to assess effectiveness. If the patient does not receive significant relief or has adverse effects from a medication, then dosing should be adjusted, an alternative medication or combination therapy should be tried, or the patient should be considered for a trial of neurostimulation. Table 1. First- and second-line medications for neuropathic pain Firstline Medications Drug Class Drug Recommendations Cautions Gabapentinoids Gabapentin Slow titration up to 600 mg PO TID. Max daily dose = 3600 mg. Reduce dose for renal impairment Pregabalin Start at 150 mg PO BID or TID. Max daily dose = 600 mg. Serotonin and norepinephrine reuptake inhibitors Duloxetine Start at 30 mg PO daily. Max daily dose = 60 mg. Renal or liver disease Venlafaxine Start at 37.5 mg PO daily. Max daily dose = 225 mg. Tr

Retigabine: Chemical Synthesis to Clinical Application - PMC

za 1 , J D Mikkelsen J D Mikkelsen 1 NeuroSearch A/S, Ballerup, Denmark Find articles by J D Mikkelsen 1 , R E Blackburn‐Munro R E Blackburn‐Munro 1 NeuroSearch A/S, Ballerup, Denmark Find articles by R E Blackburn‐Munro 1, ✉ Author information Article notes Copyright and License information 1 NeuroSearch A/S, Ballerup, Denmark * Address correspondence and reprint requests to: Dr. Gordon Blackburn‐Munro, Department of Pharmacology, NeuroSearch A/S, Pederstrupvej 93, DK‐2750 Ballerup, Denmark. Tel.: +45 4460 8333; Fax: +45 4460 8080; E‐mail: gbm@neurosearch.dk ✉ Corresponding author. Issue date 2005 Mar. PMC Copyright notice PMCID: PMC6741764 PMID: 15867950 ABSTRACT Retigabine [ D23129 ; N ‐(2‐amino‐4‐(4‐fluorobenzylamino)‐phenyl)carbamic acid ethyl ester] is an antiepileptic drug with a recently described novel mechanism of action that involves opening of neuronal K V 7.2–7.5 (formerly KCNQ2‐5) voltage‐activated K + channels. These channels (primarily K V 7.2/7.3) enable generation of the M‐current, a subthreshold K + current that serves to stabilize the membrane potential and control neuronal excitability. In this regard, retigabine has been shown to have a broad‐spectrum of activity in animal models of electrically‐induced (amygdala‐kindling, maximal electroshock) and chemically‐induced (pentylenetetrazole, picrotoxin, NMDA) epileptic seizures. These encouraging results suggest that retigabine may also prove useful in the treatment of other diseases associated with neuronal hyperexcitability. Neuropathic pain conditions are characterized by pathological changes in sensory pathways, which favor action potential generation and enhanced pain transmission. Although sometimes difficult to treat with conventional analgesics, antiepileptics can relieve some symptoms of neuropathic pain. A number of recent studies have reported that retigabine can relieve pain‐like behaviors (hyperalges

Retigabine - Wikipedia

oxin . [ 18 ] Researchers hoped this wide-ranging activity would translate to studies in humans as well. [ 8 ] Clinical trials [ edit ] In a double-blind , randomized, placebo-controlled Phase II clinical trial, retigabine was added to the treatment regimen of 399 participants with partial seizures that were refractory to therapy with other antiepileptic drugs. The frequency with which seizures occurred was significantly reduced (by 23 to 35%) in participants receiving retigabine, and approximately one fourth to one third of participants had their seizure frequency reduced by more than 50%. Higher doses were associated with a greater response to treatment. [ 8 ] [ 10 ] [ 9 ] A Phase II trial meant to assess the safety and efficacy of retigabine for treating postherpetic neuralgia was completed in 2009, but failed to meet its primary endpoint . Preliminary results were reported by Valeant as "inconclusive". [ 19 ] Regulatory approval [ edit ] The U.S. Food and Drug Administration accepted Valeant's New Drug Application for retigabine on December 30, 2009. [ 20 ] The FDA Peripheral and Central Nervous System Drugs Advisory Committee met on August 11, 2010, to discuss the process and unanimously recommended approval of Potiga for the intended indication (add-on treatment of partial seizures in adults). [ 21 ] [ 22 ] However, the possibility of urinary retention as an adverse effect was considered a significant concern, and the panel's members recommended that some sort of monitoring strategy be used to identify patients at risk of bladder dysfunction. [ 21 ] Potiga was approved by the FDA on June 10, 2010, but did not become available on the U.S. market until it had been scheduled by the Drug Enforcement Administration . [ 12 ] In December 2011, the U.S. Drug Enforcement Administration (DEA) placed the substance into Schedule V of the Controlled Substances Act (CSA), the category for substances with a comparatively low potential for abuse. This became effective 15 December 2011. [ 23 ] Name [ edit ] The International Nonproprietary Name "retigabine" was initially published as being under consideration by WHO in 1996. [ 24 ] This was later adopted as the recommended International Nonproprietary Name (rINN) for the drug, and, in 2005 or 2006, the USAN Council —a program sponsored by the American Medical Association, the United States Pharmacopeial Convention

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

NH of 12.6 (8.4–25.3) [ 2 ]. Tapentadol is a newer weak µ-receptor agonist and norepinephrine reuptake inhibitor. It is considered third- or fourth-line treatment by some guidelines due to its increased potency over tramadol [ 9 ], but the evidence was inconclusive in others [ 2 ]. Its mechanism of action is slightly different to that of tramadol, with stronger noradrenaline reuptake inhibition and nearly no effect on serotonin reuptake. Some efficacy has been shown in the treatment of DPPN [ 88 ]. Third-Line Treatment Serotonin-Specific Reuptake Inhibitors/Anticonvulsants/NMDA Antagonists For the patient who does not tolerate or fails to gain adequate pain relief from first- or second-line therapy, a referral to a specialist pain clinic is recommended [ 13 ]. The specialist setting may consider use of serotonin-specific reuptake inhibitors (SSRIs); anticonvulsants such as lamotrigine, carbamazepine, topiramate, and sodium valproate; and NMDA antagonists [ 13 ]. However, with regard to level of evidence, the most recent update of the International Congress on Neuropathic Pain (NeuSPIG) guidelines has rated all these as inconclusive [ 2 ]. At this time, it is recommended that these medications not be started in the primary care setting [ 1 ]. Interventional Therapies Epidural Injection. The recommendations around the use of epidural injections in neuropathic pain are mixed. The American Pain Society (APS) reported that there was fair evidence and provided a weak recommendation for the use of epidural steroid injection in persistent radiculopathy due to herniated lumbar disc [ 17 ]. The American Society for Interventional Pain Physicians (ASIPP) concluded that there was good evidence for caudal, interlaminar, and transforaminal epidural injections, with or without steroids, for treatment of disc herniation or radiculitis [ 18 ]. Neuropathic Pain SIG (NeuPSIG) recommendations from 2013 reported that the evidence for treatment of herpes zoster was moderate, but low for radiculopathy. They gave a “weak” recommendation for the use of epidural injections in the treatment of herpes zoster and radiculopathy. For failed back surgery syndrome (FBSS) with rad

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

-6111; Fax: +6103-9595-6110; E-mail: dbates@metropain.com.au . Issue date 2019 Jun. © 2019 American Academy of Pain Medicine. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License( http://creativecommons.org/licenses/by-nc/4.0/ ), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contactjournals.permissions@oup.com PMC Copyright notice PMCID: PMC6544553 PMID: 31152178 This article has been corrected. See Pain Med. 2022 Dec 13;24(2):219 . Abstract Background The objective of this review was to merge current treatment guidelines and best practice recommendations for management of neuropathic pain into a comprehensive algorithm for primary physicians. The algorithm covers assessment, multidisciplinary conservative care, nonopioid pharmacological management, interventional therapies, neurostimulation, low-dose opioid treatment, and targeted drug delivery therapy. Methods Available literature was identified through a search of the US National Library of Medicine’s Medline database, PubMed.gov. References from identified published articles also were reviewed for relevant citations. Results The algorithm provides a comprehensive treatment pathway from assessment to the provision of first- through sixth-line therapies for primary care physicians. Clear indicators for progression of therapy from firstline to sixth-line are provided. Multidisciplinary conservative care and nonopioid medications (tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, gabapentanoids, topicals, and transdermal substances) are recommended as firstline therapy; combination therapy (firstline medications) and tramadol and tapentadol are recommended as secondline; serotonin-specific reuptake inhibitors/anticonvulsants/NMDA antagonists and interventional therapies as third-line; neurostimulation as a fourth-line treatment; low-dose opioids (no greater than 90 morphine equivalent units) are fifth-line; and finally, targeted drug delivery is the last-line therapy for patients with refractory pain. Conclusions The presented treatment algorithm provides clear-cut tools for the assessment and treatment of neuropathic pain based on international guidelines, published data, and best practice recommendations. It

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

in most cases, TDD should be considered after low-dose oral opioid therapy has failed to provide adequate pain relief. Conclusions Neuropathic pain is highly debilitating, difficult to diagnose, and only partially responsive to nearly all treatment. A multidisciplinary, structured stepwise approach is needed to decrease pain and attain an acceptable quality of life for patients. We propose a treatment algorithm to guide the primary physician through a step-by-step, time-limited treatment process. The initial step is comprehensive assessment utilizing targeted history and examination, with screening tools such as the PainDETECT, DN4, and LANSS being used to prompt the clinician to the possibility of chronic pain. Tools such as the POMS, HADS, and Depression, Anxiety, Stress Scales (DASS) can be used to identify the presence of psychosocial consequences of neuropathic pain, and thus prompt appropriate referral to allied health. Firstline treatment includes multidisciplinary care in conjunction with TCAs, gabapentanoids, SNRIs, topical lignocaine, and capsaicin. These should be trialed over an average of four to six weeks; if acceptable pain relief is not achieved, they should be ceased, and progression to the next medication or next line of treatment should occur. Second-line treatment included tramadol and combination therapy. Tramadol is currently recommended for exacerbation of symptoms only, with caution in the elderly. Combination therapy is common in the treatment of neuropathic pain; its use should be on a trial basis for the duration of the second medication, and the patient should be followed for increased side effects and lack of efficacy. For patients who fail to respond to first- and second-line therapies, referral to a specialist pain center is recommended. In this setting, a trial of SSRIs, anticonvulsants, or NMDA receptor antagonists may be considered. Third-line treatment includes interventional therapies such as epidural injection, pulsed radiofrequency, sympathetic blockade, and adhesiolysis. They should be considered if first- and second-line therapies have failed to achieve adequate pain relief or before proceeding to neurostimulation. That said, it is important to note that all interventional therapies are limited to specific indications. Neurostimulation is proposed as a fourth-line treatment before commencement of low-dose opioids. The patient should have a diagnosis of neuropathic pain of greater than six months’

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

phrine reuptake inhibitors Duloxetine Start at 30 mg PO daily. Max daily dose = 60 mg. Renal or liver disease Venlafaxine Start at 37.5 mg PO daily. Max daily dose = 225 mg. Tricyclic antidepressants Nortriptyline Start at 10–25 mg PO QHS. Max daily dose = 150 mg. Autonomic neuropathy, urinary retention, glaucoma Taking SNRI, SSRI, MAOI, and/or tramadol Amitriptyline Start at 10–25 mg PO QHS. Max daily dose = 150 mg. Topicals (focal neuropathic pain) 5% lidocaine Available in cream or patch. Apply to site of pain 12 hours on, 12 hours off. Max of three patches at one time. 8% capsaicin Apply for 60 minutes under supervision of a physician. Avoid in diabetic peripheral neuropathy Combination therapy Gabapentinoid + TCA Only use if single agent provides inadequate relief and no adverse effects. Avoid in elderly Gabapentinoid + SNRI Titrate as indicated for single agent. Aim for lower doses of both. Weak μ-opioid agonists and serotonin and norepinephrine reuptake inhibitors Tramadol Start at 50 mg IR PO BID-QID prn. Max daily dose = 400 mg. Seizure disorder Taking SNRI, SSRI, TCA, and/or MAOI Reduce dose for renal impairment Open in a new tab BID = twice daily; IR = immediate-release; MAOI = monoamine oxidase inhibitor; PO = orally; prn = pro re nata (as needed); QHS = quaque hora somni (at night before bed); QID = four times a day; SNRI = serotonin norepinephrine reuptake inhibitor; SSRI = serotonin-specific reuptake inhibitor; TCA = tricyclic antidepressant; TID = three times daily. Tricyclic Antidepressants. TCAs are one of the most studied antidepressants for the treatment of neuropathic pain. Their use as a firstline therapy is supported across multiple guidelines [ 1–3 , 8 , 9 , 13 , 14 ]. They have been shown to be effective in the treatment of peripheral neuropathy, post-herpetic neuralgia, and neuropathic pain post–spinal cord injury and of limited effect in radic

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

authors have recommended a trial of neurostimulation before commencing low-dose opioids, placing it as fourth-line treatment after appropriate conservative, pharmacological, and interventional management has failed to achieve an acceptable quality of life for the patient. This also fits with the current CDC guidelines on commencing opioids and the 2017 Canadian guidelines on the use of opioids in chronic pain [ 9 , 100 ]. The authors have experience in both interventional and medical management of pain and have developed a predisposition toward interventional and implantable techniques based on the morbidity and mortality associated with the use of oral opioids. Fifth-Line Treatment Low-Dose Opioid Opioids have been recommended as second- [ 9 ], third- [ 2 , 3 , 8 ] or fourth-line therapy [ 14 ] for neuropathic pain. However, the authors suggest that opioids should be firmly considered fourth-line, after a trial of neurostimulation has been attempted, as per the NICE guidelines [ 1 ], and Safety, Appropriateness, Fiscal Neutrality, and Effectiveness (SAFE) analysis of neurostimulation in FBSS [ 12 ]. Concerns about a lack of long-term efficacy data and significant side effects relegate opioids to second- to fourth-line therapy [ 2 , 3 , 9 , 14 ] in most guidelines. Multiple opioids (e.g., oxycodone, morphine, methadone, and levorphanol) have demonstrated efficacy in RCTs ranging from eight days to eight weeks, in patients with a variety of neuropathic pain conditions [ 101–107 ]. On the other hand, morphine did not differ from placebo in an RCT for chronic nerve root pain [ 108 ]. The magnitude of pain reduction associated with relatively short-term opioid analgesics is at least as great as that obtained with other treatments for neuropathic pain. In a Cochrane Database review of morphine vs placebo for chronic neuropathic pain in adults, Cooper et al. found only a moderate (30%) improvement in neuropathic pain, which was experienced by 63% of patients, and the NNT to achieve this moderate reduction in pain was 3.7 (2.6–6.5) [ 109 ]. Cooper concluded that there is insufficient high-quality evidence to support or refute the suggestion that morphine is efficacious in any neuropathic pain condition. Another Cochrane Database review identified and analyzed five randomized, double-blind studies of oxycodone vs placebo for two weeks’ duration and

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

combination therapy may increase efficacy and, due to smaller doses of individual drugs, enable dose reductions and reduce side effects [ 1 , 14 ]. A Cochrane review of combination therapy for neuropathic pain demonstrated that gabapentin and opioids provide better pain relief than gabapentin or opioids alone, but this was associated with increased levels of adverse events. The calculated NNT was 9.5 (5.0–86), and the NNH was 10 (6.5–25). This indicates that approximately 10% of patients will gain benefit from the combination [ 81 ]. In a large multinational trial, the combination of duloxetine 60 mg and pregabalin 300 mg was no better than monotherapy for pain in diabetic peripheral neuropathy, but all secondary measures favored combination therapy [ 82 ]. However, in diabetic peripheral neuropathy, nortriptyline plus pregabalin was shown to be more effective at decreasing pain than monotherapy [ 83 ]. Similarly, the combination of the TCA imipramine and pregabalin saw improved pain scores, with an average two-point (31%) decrease on the Numeric Pain Rating Scale (NPRS) scale, significantly greater than pregabalin or imipramine alone; however, side effects were higher [ 84 ]. Combination therapy should be trialed for the trial duration of the second medication and ceased if ineffective or if there are significant side effects. Tramadol and Tapentadol Tramadol is considered second-line treatment in most guidelines [ 3 , 8 , 9 , 13 ] but firstline in acute neuropathic pain, cancer-related neuropathic pain, and intermittent exacerbations of neuropathic pain. Tramadol has multiple mechanisms of action but primarily acts as a weak μ-opioid agonist and inhibitor of serotonin and norepinephrine reuptake. Tramadol and has been shown to be effective in the treatment of DPPN [ 85 ], PHN [ 86 ], and cancer-related neuropathic pain [ 87 ]. Finnerup analyzed seven RCTs to demonstrate a combined NNT of 4.7 (3.6–6.7) and an NNH of 12.6 (8.4–25.3) [ 2 ]. Tapentadol is a newer weak µ-receptor agonist and norepinephrine reuptake inhibitor. It is considered third- or fourth-line

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

, 8 , 9 , 13 , 14 ]. They have been shown to be effective in the treatment of peripheral neuropathy, post-herpetic neuralgia, and neuropathic pain post–spinal cord injury and of limited effect in radiculopathy, HIV, and chemotherapy-induced peripheral neuropathy [ 8 , 46 ]. TCAs have multiple modes of action, with the most important pain-relieving effect likely being via inhibition of serotonin and norardrenaline re-uptake [ 47 ]. However, they also block histamine, adrenalin, acetylcholine, and sodium channels, accounting for their broad side effect profile [ 48 ]. Their pain-relieving effect is independent of their antidepressant effect, occurring at 20–30% of the effective antidepressant dose [ 9 ]. In a Cochrane review of 61 RCTs, it was found that TCAs had a number needed to treat (NNT) of 3.6 for the achievement of moderate pain relief and a number needed to harm (NNH) for adverse effects, defined as an event leading to withdrawal from a study, of 28. For minor adverse effects, the NNH was 9 [ 46 ]. In a separate randomized, double-blind trial of antidepressants in neuropathic pain in spinal cord injury, it was found that the NNT for TCAs at a high dose (150 mg) was 7.6, whereas the number needed to harm (NNH) was 9.2 [ 49 ]. When trialing TCAs, it is recommended that it be done over a four- to eight-week period [ 13 ]. Failure to gain adequate pain relief should result in progression to another firstline medication or combination therapy. Caution is required in the use of TCAs in the elderly and frail to avoid potential adverse effects such as falls, cardiac arrhythmias, orthostasis, urinary retention, and dry mouth. Serotonin and Norepinephrine Reuptake Inhibitors. Serotonin and norepinephrine reuptake inhibitors (SNRIs) are considered firstline treatment in multiple international guidelines [ 1–3 , 8 , 9 , 13 , 14 ]. The most commonly studied are duloxetine and venlafaxine. They facilitate descending inhibition by blocking serotonin and noradrenaline reuptake [ 3 , 9 ]. They have been shown to be effective in peripheral diabetic neuropathy, painful peripheral neuropathy [ 8 , 13 ], and more recently in

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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Profile of ezogabine (retigabine) and its potential as an adjunctive treatment for patients with partial-onset seizures - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

important to note that all interventional therapies are limited to specific indications. Neurostimulation is proposed as a fourth-line treatment before commencement of low-dose opioids. The patient should have a diagnosis of neuropathic pain of greater than six months’ duration, have a pain score of ≥5/10, and have failed to respond adequately to other therapies. Before proceeding to implant, neurostimulation should be trialed over a one- to four-week period, with a positive trial being >50% pain relief and the patient being happy with the result. Low-dose oral opioids are recommended as fifth-line due to the limited duration of efficacy and the significant risk of side effects. Commencement should be with immediate-release medication and should be titrated to the lowest possible dose. The patient should then be converted to slow-release opioids. Caution should be taken when exceeding 50 MED of morphine, and 90 MED should be exceeded only with significant justification. Patients failing to gain adequate pain relief with the above algorithm are considered to have “refractory pain.” For patients requiring >50 MED of opioids, it is recommended that a trial of TDD be considered. Due to the significant risks associated with >90 MED, it is strongly recommended that TDD be considered for these patients. Acknowledgments The authors wish to thank Linda Johnson, PhD, an independent consultant, for assistance with writing, editing, and manuscript preparation. Footnotes 1 NNT = 50% reduction in pain intensity (or 30% plus patient rating of good pain relief). 2 NNH was defined as the number needed to treat for one subject to drop out of a study due to adverse effects [ 2 ]. Funding sources: This study was funded by Abbott. Support was provided for travel to meetings to discuss the manuscript and writing/editing assistance. Conflicts of interest: Dr. Bates: Abbott, Nevro, Nalu (Consultant); Abbott (Medical Advisory Board). Dr. Schultheis: Abbott (Consultant and Sponsored Research as a PI). Dr. Hanes: Abbott, Medtronic (Consultant). Dr. Jolly: Abbott, Boston Scientific, Nevro (Consultant). Dr. Chakravarthy: Abbott, Medicell, Bioness (Consultant); Abbott, Bioness, Medicell (Advisory Board); Newrom Biomedical, Douleur Therapeutics, NanoAxis (

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

Ten percent of patients with diabetic peripheral neuropathy reported feeling “much improved,” and for HIV peripheral neuropathy, the NNT to report being “much improved” was 8.8 (5.3–2.6) [ 72 ]. Finnerup and colleagues’ meta-analysis for the treatment of PHN and HIV peripheral neuropathy demonstrated a combined NNT of 10 (7.4–19) [ 2 ]. Transdermal Substances Only lidocaine and capsaicin are referred to in the various international guidelines on management of neuropathic pain. However, some limited evidence is available on topical preparations of ketamine, amitriptyline, diclofenac, and clonidine. A transdermal approach may provide an alternative approach for some patients. It is also worth noting that some medications are ineffective topically. Ketamine at 10% has been shown to be effective in CRPS [ 73 ], whereas lower doses were not more beneficial than placebo in PHN and DPN [ 74 , 75 ]. Diclofenac may decrease burning in PHN and CRPS but has no effect on other features of neuropathic pain [ 76 ]. Clonidine has a limited effect, decreasing pain up to 30% in diabetic peripheral neuropathy [ 77 ], with an NNT of 8.33 (4.3–5.0) [ 78 ]. Alternatively, amitriptyline in concentrations of 1–5% has been shown to be ineffective in the treatment of PHN, DPN, postsurgical neuropathic pain, and painful peripheral neuropathy [ 69 ]. Second-Line Treatment Combination Therapy No one drug is effective for all patients, and, as seen above, pain relief is usually partial and side effects limit tolerability [ 13 ]. Not surprisingly, 45% of those with neuropathic pain utilize two or more medications for their pain [ 79 ]. Ninety percent of patients with DPPN require multiple medications for their pain [ 80 ]. Combination therapy is acknowledged as a significant part of the management of neuropathic pain by most guidelines; however, there is limited evidence on effective strategies [ 1 , 2 , 9 , 13 , 14 ]. In some cases, combination therapy may increase efficacy and, due to smaller doses of individual drugs, enable dose reductions and reduce side effects [ 1 , 14 ]. A Cochrane review of combination therapy for neuropathic pain demonstrated that gabapentin and opioids provide better pain relief

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

confidence interval [CI] = –1.69 to –0.84). No statistically significant results were seen for radicular pain (MD = –0.28, 95% CI = –0.62 to –0.06). A more recent meta-analysis of PRF for the treatment of cervical DRG supported its use, with positive benefits out to six months; however, gains in VAS were small, with a standardized mean difference (SMD) of −1.84, (95% CI = −2.33 to −1.34) [ 93 ]. From a practical perspective, epidural injection is likely to provide short-term benefit, and PRF possibly moderate relief out to six months. Their use in neuropathic pain can be considered when trying to control an exacerbation of pain or before moving to more invasive therapies. Due to limitations on the duration of effect, more than a single procedure may be required. Adhesiolysis. Adhesiolysis for FBSS and radicular pain is performed based on the premise that epidural adhesions are partly responsible for generation of pain. Injection of hyaluronidase, normal or hypertonic saline, and steroids is performed via a catheter in the epidural space to breakdown adhesions [ 16 ]. In the setting of failed conservative management, the ASIPP recommends the use of adhesiolysis in post–lumbar surgery syndrome and central spinal stenosis [ 18 ]. Counter to this position, NeuPSIG stated that while adhesiolysis may be beneficial in FBSS, its efficacy for neuropathic pain with FBSS is unclear, and thus provided an “inconclusive” recommendation [ 16 ]. Sympathetic Blockade. Sympathetic block with local anesthetic can be used for treatment of CRPS. High-quality evidence to confirm or refute efficacy or safety is lacking, as most studies are of short duration, providing no indication of long-term benefits [ 94 ]. NeuPSIG provided an “inconclusive” recommendation; however, given the paucity of effective treatment options for CRPS, they suggested that in patients refractory to other treatments, it was reasonable treatment option, particularly in the early phase of the disease [ 16 ]. Radiofrequency Denervation. Radiofrequency (RF) denervation is a destructive technique where the nerve is ablated using heat. Lesioning of the

Retigabine - Wikipedia

development pipeline" . Epilepsy Research . 69 (3): 273– 294. doi : 10.1016/j.eplepsyres.2006.02.004 . PMC 1562526 . PMID 16621450 . ^ "Valeant Pharmaceuticals Announces Preliminary Results From Its Phase IIa Retigabine Study for the Treatment of Postherpetic Neuralgia (PHN)" (Press release). PRNewswire. 2009-08-24 . Retrieved 2011-06-13 . ^ "Retigabine NDA accepted for filing" (Press release). PRNewswire. 2009-12-30 . Retrieved 2010-07-19 . ^ a b Lowry F (2010-08-12). "Epilepsy drug exogabine gets green light from FDA Advisory Panel" . Medscape . Retrieved 2010-08-13 . ^ [No authors listed] (2010-06-25). "August 11, 2010: Peripheral and Central Nervous System Drugs Advisory Committee Meeting Announcement" . U.S. Food and Drug Administration . Archived from the original on July 3, 2010 . Retrieved 2010-07-19 . ^ U.S. Drug Enforcement Administration (15 December 2011). "Schedules of Controlled Substances: Placement of Ezogabine Into Schedule V" (PDF) . Federal Register . 76 (241). ^ World Health Organization (1996). "International Nonproprietary Names for Pharmaceutical Substances (INN). Proposed INN: List 76" (PDF) . WHO Drug Information . 10 (4): 215. Archived from the original (PDF) on June 27, 2004. ^ [No authors listed] (2005–2006). "Statement on a nonproprietary name adopted by the USAN council: Retigabine" (PDF) . American Medical Association . Retrieved 2010-07-19 . ^ [No authors listed] (2010). "Statement on a nonproprietary name adopted by the USAN council: Ezogabine" (PDF) . American Medical Association . Archived from the original (PDF) on 2012-04-02 . Retrieved 2010-07-19 . Further reading [ edit ] Blackburn-Munro G, Dalby-Brown W, Mirza NR, Mikkelsen JD, Blackburn-Munro RE (2005). "Retigabine: chemical synthesis to clinical

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

and a thermometer to assess vasomotor responses [ 41 ]. Classically, a patient with neuropathic pain should have abnormal sensation in the area of maximal pain intensity [ 19 ]. Sensory changes should be rated as “increased,” “decreased,” or “normal”; a patient with neuropathic pain will commonly demonstrate decreased sensation to some sensory modalities and report pain in response to others [ 42 ]. The overall purpose of the examination should be to rule in, or out, the relevant neural pathways related to the patient’s history. If a neural lesion is suspected, an electroneuromyography (EMG) and nerve stimulation study (NCS) can be performed to better define the region/area of defect and narrow the possibilities. If the examination fails to reveal a clear diagnosis but neuropathic pain is still suspected, referral to neurology or a more detailed investigation using quantitative sensory testing (QST) may be warranted in ambiguous cases. Referral to a pain physician also may be indicated for diagnostic nerve blocks to further narrow down the source of the pain. Lastly, magnetic resonance imaging (MRI) or skin biopsy can be used to identify central lesions or small fiber neuropathy, respectively. Results Firstline Treatment Pain is more than just an unpleasant sensation. It can encompass emotional, social, and even spiritual suffering. Although all management strategies should strive for improvements in pain, the functional, sleep, mood, social, and spiritual consequences of pain must also be treated. It is these factors that drive much of our patients’ quality of life [ 43 ]. Multidisciplinary Team Care Multidisciplinary care is highlighted as a key component of the management of neuropathic pain by a number of guidelines [ 1 , 13 , 42 , 44 ]. Nonpharmacological and noninterventional therapies such as psychology, physiotherapy, exercise, and massage should be initiated early to address issues such as depression, anxiety, pain catastrophizing, sleep disturbance, or deconditioning, to name but a few. Multidisciplinary care in chronic neuropathic pain has been shown to statistically significantly decrease pain and improve function, mood, catastrophizing, and pain acceptance [ 45 ]. Clinically significant changes of greater than two points on a VAS scale were seen immediately post-treatment, but only 49% of patients maintained this level of pain reduction at three-month follow-up. The average pain relief at this time was 1.

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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Controlled-release oxycodon relieves neuropathic pain: A randomized controlled trial in painful diabetic neuropathy. Pain 2003;1051:71–8. [ DOI ] [ PubMed ] [ Google Scholar ] 108. Khoromi S, Cui L, Nacken L, Max MB..
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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

there is some evidence on other topical antineuropathics that may provide a practical solution in some patients who are intolerant, or in whom it is unsafe to use oral medications. Lidocaine. Topical lidocaine works by decreasing ectopic firing of peripheral nerves [ 64 ]. It is recommended as firstline [ 14 ] or second-line [ 9 ] for the treatment of focal neuropathic pain such as post-herpetic neuralgia. However, it has been shown to be ineffective in postsurgical neuropathic pain and diabetic peripheral neuropathy with allodynia or hyperalgesia [ 65 , 66 ]. It is difficult to apply topical lidocaine to the distal extremity neuropathies. A 5% lidocaine patch has been shown to be effective in five RCTs in post-herpetic neuralgia with brush allodynia [ 8 ] and to be noninferior to pregabalin with better tolerability [ 67 ]. A modest decrease in pain is commonly seen, but it is safe and well tolerated by the elderly [ 68 ]. A standard trial period should be three weeks [ 13 ]. Capsaicin. Capsaicin has its action through binding to the TRPV1 receptor located on the Aδ and C-nerve fibers. This results in release of substance P and depolarization of the nerve. Long-term exposure causes overstimulation, depletion of substance P, desensitization of the nerve, and reversible nerve degeneration [ 69 ]. High-concentration capsaicin (8%) is recommended as third-line [ 70 ], fourth-line, and as an alternative in focal neuropathic pain for those who “wish to avoid, or who cannot tolerate, oral treatments” [ 1 ]. Capsaicin is painful on initial application, and its efficacy depends on regular consistent use, thus making compliance with a capsaicin-based regimen challenging for many [ 71 ]. A recent Cochrane review of 8% capsaicin in PHN showed 30–50% pain relief at 12 weeks, and the NNT was 10–12 for PHN and 11 for HIV-related peripheral neuropathy. Ten percent of patients with diabetic peripheral neuropathy reported feeling “much improved,” and for HIV peripheral neuropathy, the NNT to report being “much improved” was 8.8 (5.3–2.6)

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

Pulsed radiofrequency treatment in interventional pain management: Mechanisms and potential indications—a review. Acta Neurochir (Wien) 2011;1534:763–71. [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 91. Chang MC.
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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

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A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

, Finnerup et al. from 13 trials of strong opioids calculated a combined NNT of 4.3 (3–4.5.8), with an NNH of 11.7 (8.4–19.3) [ 2 ]. CDC and Canadian guidelines on use of opioids in noncancer chronic pain recommend optimization of nonpharmacological and non-opioid-based therapies [ 113 , 114 ]. Commencement should be with immediate-release forms of the drug with the aim of utilizing the lowest possible dose. The patient is converted to slow release once a stable, effective dose has been achieved. Caution should be taken when exceeding 50 mg per day of morphine (or morphine equivalent dose [MED]), and >90 MED should be avoided or have careful justification. A trial of therapy should occur for one to four weeks, after which the benefits relative to the risks should once again be reviewed. This should occur every three months [ 113 ]. Sixth-Line Treatment Targeted Drug Delivery Targeted drug delivery is used to deliver medications directly to their site of action at the dorsal horn of the spinal cord, bypassing the first pass effect and the blood–brain barrier. This significantly increases the potency of the medication, allowing much smaller doses to be used [ 115 ]. Currently, morphine and ziconotide are the only Food and Drug Administration–approved pain medications for TDD. Recommendations for the use of targeted drug delivery vary between organizations. NeuPSIG rates its strength of recommendation as “inconclusive” [ 16 ]. The APS guidelines state that for nonradicular pain there is insufficient evidence to evaluate benefits of intrathecal therapy with opioids or other medications. However, no reference is made to radicular or neuropathic pain for the use of TDD [ 17 ]. ASSIP concluded in the positive and stated, “Intrathecal infusion pumps are indicated in the treatment of recalcitrant non-cancer pain with post-surgery syndrome” [ 18 ]. The Polyanalgesic Consensus Conference (PACC) recommends the use of TDD for those with refractory pain [ 15 ]. TDD is included in this algorithm as a management option for patients who are considered to suffer refractory pain: Pain is defined as refractory, regardless of etiology, when 1) multiple evidence-based biomedical therapies used in a clinically appropriate and acceptable fashion have failed to reach treatment goals that may include adequate pain reduction

Clinical utility, safety, and tolerability of ezogabine (retigabine) in the treatment of epilepsy - PMC

us. Pharmacol Res. 2011;64(4):397–409. doi: 10.1016/j.phrs.2011.06.016. [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 39. Streng T, Christoph T, Andersson KE. Urodynamic effects of the K+ channel (KCNQ) opener retigabine in freely moving, conscious rats. J Urol. 2004;172(5 Pt 1):2054–2058. doi: 10.1097/01.ju.0000138155.33749.f4. [ DOI ] [ PubMed ] [ Google Scholar ] 40. Rode F, Svalø J, Sheykhzade M, Christian L, Rønn LC. Functional effects of the KCNQ modulators retigabine and XE991 in the rat urinary bladder. Eur J Pharmacol. 2010;638(1–3):121–127. doi: 10.1016/j.ejphar.2010.03.050. [ DOI ] [ PubMed ] [ Google Scholar ] 41. Shillito P, Molenaar PC, Vincent A, et al. Acquired neuromyotonia: evidence for autoantibodies directed against K+ channels of peripheral nerves. Ann Neurol. 1995;38(5):714–722. doi: 10.1002/ana.410380505. [ DOI ] [ PubMed ] [ Google Scholar ] 42. Blackburn-Munro G, Jensen BS. The anticonvulsant retigabine attenuates nociceptive behaviors in rat models of persistent and neuropathic pain. Eur J Pharmacol. 2003;460(2–3):109–116. doi: 10.1016/s0014-2999(02)02924-2. [ DOI ] [ PubMed ] [ Google Scholar ] 43. Munro G, Erichsen HK, Mirza NR. Pharmacological comparison of anticonvulsant drugs in animal models of persistent pain and anxiety. Neuropharmacology. 2007;53(5):609–618. doi: 10.1016/j.neuropharm.2007.07.002. [ DOI ] [ PubMed ] [ Google Scholar ] 44. Hansen HH, Andreasen JT, Weikop P, Mirza M, Scheel

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

drug delivery is the last-line therapy for patients with refractory pain. Conclusions The presented treatment algorithm provides clear-cut tools for the assessment and treatment of neuropathic pain based on international guidelines, published data, and best practice recommendations. It defines the benefits and limitations of the current treatments at our disposal. Additionally, it provides an easy-to-follow visual guide of the recommended steps in the algorithm for primary care and family practitioners to utilize. Keywords: Spinal Cord Stimulation, Neuromodulation, Pharmacological Treatment, Neuropathic Pain, Targeted Drug Delivery Introduction Neuropathic pain has a significant impact on patients’ quality of life, as well as social, economic, and psychological well-being [ 1 ]. Notably, it has an even larger economic burden on society as a whole when one considers the financial cost of managing it in the chronic setting [ 2 , 3 ]. Estimates of its prevalence in the general population vary from as little as 1% to as much as 7–8% [ 4 , 5 ]; however, when taking into account conditions such as diabetes (26%), herpes zoster/shingles (19%), and postsurgical pain (10%), the incidence is much higher [ 1 ]. There are a number of national and international guidelines/recommendations for the assessment and treatment of neuropathic pain, yet there remains to be a consensus or agreement on the positioning of pharmacologic management (specifically opioids), neurostimulation, or targeted drug delivery [ 1 , 2 , 6–18 ]. The purpose of this publication is to create a comprehensive algorithm for the treatment and management of chronic, noncancer neuropathic pain by merging the aforementioned guidelines/recommendations and integrating the currently available data from systemic reviews, randomized controlled trials (RCTs), and published case reports/series ( Figure 1 ). Figure 1. Open in a new tab Comprehensive algorithm for the management of neuropathic pain. Methods All guidelines focused on the assessment of neuropathic pain highlight the use of a comprehensive history and examination with reliance on clinical judgment in the interpretation of screening tools and investigations [ 1 , 6 , 7 ]. History Neuropathic pain stems from a wide variety of causes that can be broadly organized into two basic categories: peripheral and central etiologies [ 19 ]. However, presentation may be variable both between peripheral and central etiologies and within individuals with the same etiology [ 20 ]. Common peripheral neuropathic conditions include diabetic peripheral polyneuropathy, chemotherapy-induced peripheral

Retigabine - Wikipedia

Retigabine - Wikipedia Jump to content Main menu Main menu move to sidebar hide Navigation Main page Contents Current events Random article About Wikipedia Contact us Contribute Help Learn to edit Community portal Recent changes Upload file Special pages Search Search Appearance Donate Create account Log in Personal tools Donate Create account Log in Pages for logged out editors learn more Contributions Talk Contents move to sidebar hide (Top) 1 Adverse effects 2 Interactions 3 Pharmacology Toggle Pharmacology subsection 3.1 Mechanism of action 3.2 Pharmacokinetics 4 History Toggle History subsection 4.1 Clinical trials 4.2 Regulatory approval 5 Name 6 References 7 Further reading Toggle the table of contents Retigabine 11 languages العربية Deutsch Español فارسی Français Polski Română Српски / srpski Srpskohrvatski / српскохрватски Tiếng Việt 中文 Edit links Article Talk English Read Edit View history Tools Tools move to sidebar hide Actions Read Edit View history General What links here Related changes Upload file Permanent link Page information Cite this page Get shortened URL Download QR code Print/export Download as PDF Printable version In other projects Wikimedia Commons Wikidata item Appearance move to sidebar hide From Wikipedia, the free encyclopedia Anticonvulsant, which works as a potassium-channel opener Pharmaceutical compound Retigabine Clinical data Trade names Trobalt, Potiga Other names D-23129, ezogabine ( USAN US ) AHFS / Drugs.com Professional Drug Facts MedlinePlus a612028 License data EU EMA : by INN US FDA : Ezogabine Routes of administration By mouth ATC code N03AX21 ( WHO ) Legal status Legal status AU : S4 (Prescription only) UK : POM (Prescription only) US : Schedule V Pharmacokinetic data Bioavailability 60% Protein binding 60–80% Metabolism Liver glucuronidation and acetylation . CYP not involved Elimination half-life 8 hours (mean), range: 7–11 hours [ 1 ] Excretion Kidney (84%) Identifiers IUPAC name Ethyl N -[2-amino-4-[(4-fluorophenyl)methylamino]phenyl]carbamate

Profile of ezogabine (retigabine) and its potential as an adjunctive treatment for patients with partial-onset seizures - PMC

/WNL.0b013e3181fd6170. [ DOI ] [ PubMed ] [ Google Scholar ] 25. French JA, Abou-Khalil BW, Leroy RF, et al. Randomized, double-blind, placebo-controlled trial of ezogabine (retigabine) in partial epilepsy. Neurology. 2011;76:1555–1563. doi: 10.1212/WNL.0b013e3182194bd3. [ DOI ] [ PubMed ] [ Google Scholar ] 26. Streng T, Christoph T, Andersson KE. Urodynamic effects of the K+ channel (KCNQ) opener retigabine in freely moving, conscious rats. J Urol. 2004;172:2054–2058. doi: 10.1097/01.ju.0000138155.33749.f4. [ DOI ] [ PubMed ] [ Google Scholar ] 27. Rode F, Svalo J, Sheykhzade M, Ronn LCB. Functional effects of the KCNQ modulators retigabine and XE991 in the rat urinary bladder. Eur J Pharmacol. 2010;638:121–127. doi: 10.1016/j.ejphar.2010.03.050. [ DOI ] [ PubMed ] [ Google Scholar ] 28. McNeilly RJ, Torchin CD, Anderson LW, Kapetanovic IM, Kupferberg HJ, Strong JM. In vitro glucuronidation of D-23129, a novel anticonvulsant, by human liver microsomes and liver slices. Xenobiotica. 1997;27:431–441. doi: 10.1080/004982597240424. [ DOI ] [ PubMed ] [ Google Scholar ] 29. Hempel R, Schupke H, McNeilly PJ, et al. Metabolism of retigabine (D-23129), a novel anticonvulsant. Drug Metab Dispos. 1999;27:613–622. [ PubMed ] [ Google Scholar ] 30. Hiller A, Nguyen N, Strassburg C, et al. Retigabine N-glucuronidation and its potential role in enterohepatic circulation. Drug Metab Dispos. 1999;27:

Profile of ezogabine (retigabine) and its potential as an adjunctive treatment for patients with partial-onset seizures - PMC

Retigabine: Chemical Synthesis to Clinical Application - PMC

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Retigabine - Wikipedia

channel opener —that is, by activating a certain family of voltage-gated potassium channels in the brain. [ 5 ] [ 6 ] [ 7 ] This mechanism of action is unique among antiepileptic drugs, and may hold promise for the treatment of other neurologic conditions, including tinnitus , migraine and neuropathic pain . The manufacturer withdrew retigabine from clinical use in 2017. Adverse effects [ edit ] The adverse effects found in the Phase II trial mainly affected the central nervous system, and appeared to be dose-related. [ 8 ] The most common adverse effects were drowsiness , dizziness , tinnitus and vertigo , confusion, and slurred speech . [ 9 ] Less common side effects included tremor , memory loss, gait disturbances, and double vision . [ 10 ] In 2013, FDA warned the public that Potiga (ezogabine) can cause blue skin discoloration and eye abnormalities characterized by pigment changes in the retina. FDA does not currently know if these changes are reversible. FDA is working with the manufacturer to gather and evaluate all available information to better understand these events. FDA will update the public when more information is available. [ 11 ] Psychiatric symptoms and difficulty urinating have also been reported, with most cases occurring in the first 2 months of treatment. [ 12 ] [ 13 ] Interactions [ edit ] Retigabine appears to be free of drug interactions with most commonly used anticonvulsants. It may increase metabolism of lamotrigine (Lamictal), whereas phenytoin (Dilantin) and carbamazepine (CBZ, Tegretol) increase the clearance of retigabine. [ 13 ] [ 14 ] Concomitant use of retigabine and digoxin may increase serum concentration of the latter. In vitro studies suggest that the main metabolite of retigabine acts as a P-glycoprotein inhibitor, and may thus increase absorption and reduce elimination of digoxin. [ 13 ] Pharmacology [ edit ] Mechanism of action [ edit ] Retigabine acts as a neuronal KCNQ / Kv7 potassium channel opener , a mechanism of action markedly different from that of any current anticonvulsants. [ 5 ] [ 6 ] [ 7 ] This mechanism of action is similar to that of the chemically similar flupirtine , [ 15 ] which is used mainly for its analgesic properties. The

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

high-quality evidence to support or refute the suggestion that morphine is efficacious in any neuropathic pain condition. Another Cochrane Database review identified and analyzed five randomized, double-blind studies of oxycodone vs placebo for two weeks’ duration and longer for chronic neuropathic pain in adults, reporting on 687 participants (637) with painful diabetic neuropathy and 50 with post-herpetic neuralgia [ 110 ]. Gaskell et al. found that none of the five studies reported pain relief of 50% or greater. Three studies including 537 participants with diabetic neuropathy showed a moderate pain relief of 30% in only 44% of the patients. The associated number needed to treat for an additional beneficial outcome was 5.7. More participants experienced adverse events with oxycodone alone (86%) than with placebo (63%); the number needed to treat for an additional harmful outcome (NNH) was 4.3. As a result, Gaskell et al. concluded that there was very low-quality evidence to support the long-term treatment of patients with painful diabetic neuropathy and PHN with oxycodone. Furthermore, in conducting their literature search, Gaskell et al. found no studies of oxycodone for any other neuropathic pain conditions. In 2010, Finnerup et al. reviewed 174 placebo-controlled RCTs (105 from an earlier review in 2005 and 69 additional as of 2010) of firstline drugs, including opioids, for chronic neuropathic pain [ 111 , 112 ]. They calculated an NNT to achieve ≥30% pain reduction and an NNH (number treated for one patient to drop out of the study due to adverse effects) for specific drug classes and pain etiologies. In the case of opioids, the NNT ranged from 2.1 (1.5–3.3) for mixed neuropathic pain to 5.1 (2.7–36.0) for peripheral nerve injury. The combined NNH for opioids for all etiologies was 17.1 (9.9–66). The authors concluded that the lack of proven long-term effectiveness and the high risk for adverse effects called for alternative treatment options to target chronic neuropathic pain. More recently, Finnerup et al. from 13 trials of strong opioids calculated a combined NNT of 4.3 (3–4.5.8), with an NNH of 11.7 (8.4–19.3) [ 2

Clinical utility, safety, and tolerability of ezogabine (retigabine) in the treatment of epilepsy - PMC

Khalil BW, Leroy RF, et al. RESTORE 1/Study 301 Investigators. Randomized double-blind, placebo-controlled trial of ezogabine (retigabine) in partial epilepsy. Neurology. 2011;76(18):1555–1563. doi: 10.1212/WNL.0b013e3182194bd3. [ DOI ] [ PubMed ] [ Google Scholar ] 35. Brodie MJ, Lerche H, Gil-Nagel A, et al. RESTORE 2 Study Group. Efficacy and safety of adjunctive ezogabine (retigabine) in refractory partial epilepsy. Neurology. 2010;75(20):1817–1824. doi: 10.1212/WNL.0b013e3181fd6170. [ DOI ] [ PubMed ] [ Google Scholar ] 36. Porter RJ, Burdette DE, Gil-Nagel A, et al. Retigabine as adjunctive therapy in adults with partial-onset seizures: integrated analysis of three pivotal controlled trials. Epilepsy Res. doi: 10.1016/j.eplepsyres.2012.03.010. Epub April 16, 2012. [ DOI ] [ PubMed ] [ Google Scholar ] 37. Brickel N, Gandhi P, Vanlandingham K, Hammond J, Derossett S. The urinary safety profile and secondary renal effects of retigabine (ezogabine): a first-in-class antiepileptic drug that targets KCNQ (K(v) 7) potassium channels. Epilepsia. 2012;53(4):606–612. doi: 10.1111/j.1528-1167.2012.03441.x. [ DOI ] [ PubMed ] [ Google Scholar ] 38. Ipaveca V, Martirea M, Barreseb V, Taglialatela M, Currò D. KV7 channels regulate muscle tone and nonadrenergic noncholinergic relaxation of the rat gastric fundus. Pharmacol Res. 2011;64(4):397–409. doi: 10.1016/j.phrs.2011.06.016. [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 39

A Comprehensive Algorithm for Management of Neuropathic Pain - PMC

colleagues, compared neurostimulation with medical therapies. Lamer et al. concluded that spinal cord stimulation produced better pain reduction than medical therapy in patients with chronic spine and leg pain [ 98 ]. This analysis found that compared with medical therapy, conventional spinal cord stimulation (low frequency, paresthesia based) significantly increased the odds of achieving 50% pain relief (odds ratio [OR] = 13.1, 95% CI = 4.46 to 34.17) and significantly decreased pain on a visual analog scale. Furthermore, newer neuromodulation technologies including high-frequency and burst spinal cord stimulation and dorsal root ganglion stimulation were shown to have an even greater odds of decreasing pain than conventional spinal cord stimulation (OR = 2.37, 95% CI = 1.58 to 3.54). Currently, NeuPSIG recommendations on interventional management of neuropathic pain are “inconclusive” for the use of spinal cord stimulation in PHN, DPN, spinal cord injury, and poststroke pain [ 16 ]. Counter to this position, NICE updated their guidelines for spinal cord stimulation most recently in 2014 [ 97 ], and their Neuropathic Pain Overview recommendations in 2018 [ 96 ]. They recommended spinal cord stimulation as a treatment option for all chronic pain conditions of neuropathic origin, with ≥50/100 on a 100-mm VAS, and that have persisted for at least six months despite appropriate medical management. Importantly, they recommended that the patient have a successful trial of stimulation (>50% pain relief) before permanent implant and that care be provided in a multidisciplinary environment. A systematic review of spinal cord stimulation for failed back surgery syndrome noted that the biological consequences of SCS were less than those of long-term opioid use and concluded that spinal cord stimulation should be placed before long-term opioids in the treatment algorithm [12]. Recently, Krebs et al. [ 99 ] reported the results of a randomized trial of patients with chronic back, hip, or knee pain, showing no benefit of opioid medications over nonopioid medications for pain-related function or pain intensity over 12 months of follow-up. With consideration of the limited efficacy of opioids in neuropathic pain, the authors have recommended a trial of neurostimulation before commencing low-dose opioids, placing it as fourth-line treatment after appropriate conservative, pharmacological, and interventional management has failed to achieve an acceptable quality of life for the patient. This also

Profile of ezogabine (retigabine) and its potential as an adjunctive treatment for patients with partial-onset seizures - PMC

igabine. J Neurosci. 2001;21:5535–5545. doi: 10.1523/JNEUROSCI.21-15-05535.2001. [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 15. Rundfeldt C, Netzer R. Investigations into the mechanism of action of the new anticonvulsant retigabine. Interaction with GABAergic and glutamatergic neurotransmission and with voltage gated ion channels. Arzneimittelforschung. 2000;50:1063–1070. doi: 10.1055/s-0031-1300346. [ DOI ] [ PubMed ] [ Google Scholar ] 16. van Rijn CM, Willems-van Bree E. Synergy between retigabine and GABA in modulating the convulsant site of the GABAA receptor complex. Eur J Pharmacol. 2003;464:95–100. doi: 10.1016/s0014-2999(03)01426-2. [ DOI ] [ PubMed ] [ Google Scholar ] 17. Rostock A, Tober C, Rundfeldt C, et al. D-23129: a new anticonvulsant with a broad spectrum activity in animal models of epileptic seizures. Epilepsy Res. 1996;23:211–223. doi: 10.1016/0920-1211(95)00101-8. [ DOI ] [ PubMed ] [ Google Scholar ] 18. De Sarro G, Di Paola ED, Conte G, Pasculli MP, De Sarro A. Influence of retigabine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice. Naynyn Schmiedebergs Arch Pharmacol. 2001;363:330–336. doi: 10.1007/s002100000361. [ DOI ] [ PubMed ] [ Google Scholar ] 19. Mazarati A, Wu J, Shin D, Kwon YS, Sankar R. Antiepileptogenic and antiictogenic effects of retigabine under conditions of rapid kindling: an ontogenic study. Epilepsia. 2008;49:1777–1786. doi: 10.1111/j.