Lamotrigine in the treatment of chronic refractory neuropathic pain

Lamotrigine for chronic neuropathic pain and fibromyalgia in adults

BACKGROUND

This is an update of the original Cochrane review entitled Lamotrigine for acute and chronic pain published in Issue 2, 2007, and updated in Issue 2, 2011. Some antiepileptic medicines have a place in the treatment of neuropathic pain (pain due to nerve damage). This updated review adds no new additional studies looking at evidence for lamotrigine as an effective treatment for chronic neuropathic pain or fibromyalgia. The update uses higher standards of evidence than previously.

OBJECTIVES

To assess the analgesic efficacy of lamotrigine in the treatment of chronic neuropathic pain and fibromyalgia, and to evaluate adverse effects reported in the studies.

SEARCH METHODS

We identified randomised controlled trials (RCTs) of lamotrigine for chronic neuropathic pain and fibromyalgia (including cancer pain) from MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). We ran searches for the original review in 2006, in 2011 for the first update, and subsequent searches in August 2013 for this update. We sought additional studies from the reference lists of the retrieved papers. The original review and first update included acute pain, but no acute pain studies were identified.

SELECTION CRITERIA

RCTs investigating the use of lamotrigine (any dose, by any route, and for any study duration) for the treatment of chronic neuropathic pain or fibromyalgia. Assessment of pain intensity or pain relief, or both, using validated scales. Participants were adults aged 18 and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. The first tier used data where studies reported the outcome of at least 50% pain reduction from baseline, lasted at least eight weeks, had a parallel group design, included 200 or more participants in the comparison, and reported an intention-to-treat analysis. First-tier studies did not use last observation carried forward (LOCF) or other imputational methods for dropouts. The second tier used data that failed to meet this standard and second-tier results were therefore subject to potential bias.

MAIN RESULTS

Twelve included studies in 11 publications (1511 participants), all with chronic neuropathic pain: central post-stroke pain (1), chemotherapy-induced neuropathic pain (1), diabetic neuropathy (4), HIV-related neuropathy (2), mixed neuropathic pain (2), spinal cord injury-related pain (1), and trigeminal neuralgia (1). We did not identify any additional studies. Participants were aged between 26 and 77 years. Study duration was two weeks in one study and at least six weeks in the remainder; eight were of eight-week duration or longer.No study provided first-tier evidence for an efficacy outcome. There was no convincing evidence that lamotrigine is effective in treating neuropathic pain and fibromyalgia at doses of 200 mg to 400 mg daily. Almost 10% of participants taking lamotrigine reported a skin rash.

AUTHORS' CONCLUSIONS

Large, high-quality, long-duration studies reporting clinically useful levels of pain relief for individual participants provided no convincing evidence that lamotrigine is effective in treating neuropathic pain and fibromyalgia at doses of about 200 to 400 mg daily. Given the availability of more effective treatments including antiepileptics and antidepressant medicines, lamotrigine does not have a significant place in therapy based on the available evidence. The adverse effect profile of lamotrigine is also of concern.

Lamotrigine for acute and chronic pain

BACKGROUND

This is an update of the original Cochrane review published in Issue 2, 2007. Some antiepileptic medicines have a place in the treatment of neuropathic pain (pain due to nerve damage). This updated review adds five new additional studies looking at evidence for Lamotrigine as an effective treatment for acute and chronic pain.

OBJECTIVES

To assess analgesic efficacy and adverse effects of the antiepileptic drug lamotrigine in acute and chronic pain.

SEARCH STRATEGY

Randomised controlled trials (RCTs) of lamotrigine in acute, and chronic pain (including cancer pain) were identified from MEDLINE, EMBASE and CENTRAL up to January 2011. Additional studies were sought from the reference list of the retrieved papers.

SELECTION CRITERIA

RCTs investigating the use of lamotrigine (any dose, by any route, and for any study duration) for the treatment of acute or chronic pain. Assessment of pain intensity or pain relief, or both, using validated scales. Participants were adults aged 18 and over. Only full journal publication articles were included.

DATA COLLECTION AND ANALYSIS

Dichotomous data (ideally for the outcome of at least 50% pain relief) were used to calculate relative risk with 95% confidence intervals. Meta-analysis was undertaken using a fixed-effect model. Numbers needed to treat to benefit (NNTs) were calculated as the reciprocal of the absolute risk reduction. For unwanted effects, the NNT becomes the number needed to harm (NNH) and was calculated.

MAIN RESULTS

Twelve included studies in 11 publications (1511 participants), all with chronic neuropathic pain: central post stroke pain (1), chemotherapy induced neuropathic pain (1), diabetic neuropathy (4), HIV related neuropathy (2), mixed neuropathic pain (2), spinal cord injury related pain (1), and trigeminal neuralgia (1); none investigated lamotrigine in acute pain. The update had five additional studies (1111 additional participants). Participants were aged between 26 and 77 years. Study duration was 2 weeks in one study and at least 6 weeks in the remainder; eight were of eight week duration or longer. There is no convincing evidence that lamotrigine is effective in treating acute or chronic pain at doses of about 200-400 mg daily. Almost 10% of participants taking lamotrigine reported a skin rash.

AUTHORS' CONCLUSIONS

The additional studies tripled participant numbers providing data for analysis, and new, more stringent criteria for outcomes and analysis were used; conclusions about lamotrigine's lack of efficacy in chronic pain did not change. Given availability of more effective treatments including antiepileptics and antidepressant medicines, lamotrigine does not have a significant place in therapy based on available evidence.

Antiepileptic drugs to treat pain in rheumatic conditions. Recommendations based on evidence-based review of the literature and expert opinion

OBJECTIVES

Neuropathic pain is commonly encountered in rheumatology practice, often associated with nociceptive mechanisms. It is caused by nervous system lesions, and the usual treatments with analgesics and anti-inflammatory drugs are mostly ineffective. Antiepileptic drugs (AED) have proved effective in relieving neuropathic pain. AED are recently used by rheumatologists since the role of neuropathic pain in rheumatological conditions has only recently been documented. Nevertheless, the tendency seems to be reversed when these drugs are used inappropriately. The CEDR (Cercle d'Etude de la Douleur en Rhumatologie), a specific interest group of the French Society of Rheumatology that focuses on pain in rheumatology, undertook to develop recommendations for the use of AED in Rheumatology.

METHODS

A list of questions concerning the prescription of AED in painful rheumatic conditions was validated by a working group of 7 experts from the CEDR. The list of questions was used to draw up the recommendations. A literature review was performed using electronic databases (Medline, Embase and Cochrane library between 1980 and 2007) without limitations on the type of publication: case reports, clinical trials, literature review and guidelines about therapeutic management of neuropathic pain. Selected studies were scored for quality. Based on the literature and clinical experience, recommendations were developed using the Delphi method.

RESULTS

We identified 29 studies concerning the use of AED in painful rheumatic conditions and 16 studies were considered valid and scored for quality. These few studies, the guidelines published for neuropathic pain treatment and the clinical experience of each expert, were used to develop 11 recommendations for the use of AED in painful rheumatic conditions.

CONCLUSION

These recommendations can be used as guidelines to help prescribers to use AED for the management of pain in rheumatic conditions until further scientific evidence becomes available.

Double-blind, placebo-controlled trial of lamotrigine in combination with other medications for neuropathic pain

This randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy and tolerability of lamotrigine added to gabapentin, a tricyclic antidepressant, or a nonopioid analgesic in patients whose neuropathic pain was inadequately controlled with these medications. Patients with neuropathic pain from diabetic peripheral neuropathy, postherpetic neuralgia, traumatic/surgical nerve injury, incomplete spinal cord injury, trigeminal neuralgia, multiple sclerosis, or HIV-associated peripheral neuropathy, who had a mean weekly pain score > or =4 on an 11-point numerical rating scale, were randomized to receive a flexible dose of lamotrigine 200, 300, or 400mg daily (n=111) or placebo (n=109) for up to 14 weeks (including eight weeks of dose escalation) in addition to their prestudy regimen of gabapentin, a tricyclic antidepressant, or a nonopioid analgesic. No statistically significant difference in the mean change in pain-intensity score from baseline to Week 14 (primary endpoint) was detected between lamotrigine and placebo (P=0.67). Differences between lamotrigine and placebo were not statistically significant for secondary efficacy assessments, including mean changes from baseline in the Short-Form McGill Pain Questionnaire, the Neuropathic Pain Scale, rescue medication use, and the percentages of patients rated as much improved or very much improved at the end of treatment on the Clinician Global Impression of Change scale and the Patient Global Impression of Change scale. Lamotrigine was generally well tolerated. Lamotrigine (up to 400 mg/day) added to gabapentin, a tricyclic antidepressant, or a nonopioid analgesic did not demonstrate efficacy as an adjunctive treatment of neuropathic pain but was generally safe and well tolerated.

Antiepileptic drugs in the treatment of neuropathic pain

Antiepileptic drugs are an effective treatment for various forms of neuropathic pain of peripheral origin, although they rarely provide complete pain relief. Multiple multicentre randomised controlled trials have shown clear efficacy of gabapentin and pregabalin for postherpetic neuralgia and painful diabetic neuropathy. Theses drugs can be rapidly titrated and are well tolerated. Topiramate, lamotrigine, carbamazepine and oxcarbazepine are alternatives for the treatment of painful diabetic neuropathy, but should be titrated slowly. Carbamazepine remains the drug of choice for trigeminal neuralgia; however, oxcarbazepine and lamotrigine are potential alternatives. There is an apparent need for large-scale randomised controlled trials on the efficacy of antiepileptic drugs in neuropathic pain in general, and in cancer-related neuropathic pain and neuropathic pain of central origin in particular. Trials with long-term follow-up are required to establish the long-term efficacy of antiepileptic drugs in neuropathic pain. There is only limited scientific evidence to support the idea that drug combinations are likely to be more efficacious and safer than each drug alone; further studies are warranted in this area.

Lamotrigine for acute and chronic pain

BACKGROUND

Anticonvulsant medicines have a place in the treatment of neuropathic pain (pain due to nerve damage). This review looks at the evidence for the pain relieving properties of lamotrigine.

OBJECTIVES

To assess the analgesic efficacy and adverse effects of the anticonvulsant lamotrigine for acute and chronic pain.

SEARCH STRATEGY

Randomised Controlled Trials (RCTs) of lamotrigine (and key brand names Lamictal, Lamictin, Neurium) in acute, chronic or cancer pain were identified from MEDLINE (1966 to August 2006), EMBASE 1994 to August 2006 and the CENTRAL register on The Cochrane Library (Issue 3, 2006). Additional reports were sought from the reference list of the retrieved papers.

SELECTION CRITERIA

RCTs investigating the use of lamotrigine (any dose and by any route) for treatment of acute or chronic pain. Assessment of pain intensity or pain relief, or both, using validated scales. Participants were adults aged 18 and over. Only full journal publication articles were included.

DATA COLLECTION AND ANALYSIS

Dichotomous data were used to calculate relative risk with 95% confidence intervals using a fixed effects model unless significant statistical heterogeneity was found. Continuous data was also reported where available. Meta-analysis was undertaken using a fixed effect model unless significant heterogeneity was present (I(2) >50%) in which case a random effects model was used. Numbers-needed-to-treat (NNTs) were calculated as the reciprocal of the absolute risk reduction. For unwanted effects, the NNT becomes the number-needed-to-harm (NNH) and was calculated.

MAIN RESULTS

Sixteen studies were identified. Nine studies were excluded. No studies for acute pain were identified. The seven included studies involved 502 participants, all for neuropathic pain. The studies covered the following conditions: central post stroke pain (1), diabetic neuropathy (1), HIV related neuropathy (2), intractable neuropathic pain (1), spinal cord injury related pain (1) and trigeminal neuralgia (1). The studies included participants in the age range of 26 to 77 years. Only one study for HIV related neuropathy had a statistically significant result for a sub group of patients on anti-retroviral therapy; this result is unlikely to be clinically significant NNT 4.3 (95% CI 2.3 to 37). Approximately 7% of participants taking lamotrigine reported a skin rash.

AUTHORS' CONCLUSIONS

Given the availability of more effective treatments including anticonvulsants and antidepressant medicines, lamotrigine does not have a significant place in therapy at present. The limited evidence currently available suggests that lamotrigine is unlikely to be of benefit for the treatment of neuropathic pain.

Lamotrigine for treatment of pain associated with diabetic neuropathy: results of two randomized, double-blind, placebo-controlled studies

To assess the efficacy and tolerability of lamotrigine in pain associated with diabetic neuropathy, two replicate randomized, double-blind, placebo-controlled studies were conducted. Patients (n=360 per study) with painful diabetic neuropathy were randomized to receive lamotrigine 200, 300, or 400 mg daily or placebo during the 19-week treatment phase, including a 7-week dose-escalation phase and a 12-week, fixed-dose maintenance phase. The mean reduction in pain-intensity score from baseline to week 19 (primary endpoint) was greater (p < or = 0.05) in patients receiving lamotrigine 400 mg than placebo in Study 2 (observed scores, -2.7 versus -1.6 on a 0- to 10-point scale). This finding was not replicated in Study 1. Lamotrigine 200 and 300 mg did not significantly differ from placebo at week 19 in either study. Lamotrigine 300 and 400 mg were only occasionally more effective than placebo for secondary efficacy endpoints. The 200-mg dose did not separate from placebo. In a post hoc analysis of pooled data including only patients who reached their target dose, lamotrigine 400 mg conferred greater (p0.05) mean reduction in pain-intensity score from baseline to week 19 than placebo (-2.5 for 300 mg and -2.7 for 400mg versus -2.0 for placebo). Adverse events were reported in 71-82% of lamotrigine-treated patients compared with 63-70% of placebo-treated patients. The most common adverse events with lamotrigine were headache and rash. Compared with placebo, lamotrigine (300 and 400 mg daily) was inconsistently effective for pain associated with diabetic neuropathy but was generally safe and well tolerated.

Lamotrigine for neuropathic pain

Lamotrigine is an antiepileptic drug that stabilizes neural membranes by blocking the activation of voltage-sensitive sodium channels and inhibiting the presynaptic release of glutamate. Full length reports of five open trials and six out of seven randomized controlled trials (plus two abstracts) have demonstrated the efficacy of lamotrigine in the treatment of various forms of neuropathic pain. The present drug profile provides a review of the pharmacologic properties of lamotrigine, the clinical evidence related to its efficacy and safety, and discusses the current and future role of the drug in the treatment of neuropathic pain.

Use of Lamotrigine in Glossopharyngeal Neuralgia: A Case Report

We describe a case of a patient with glossopharyngeal neuralgia (refractory to treatment with carbamazepine, amytriptyline, diazepam, and indomethacin) treated with lamotrigine as monotherapy, the first described, who responded completely to the therapy and did not complain of side effects. The complete analgesic effect was reached at the lamotrigine daily dose of 200 mg per day and was maintained at that dose for additional 6 months, with the blood concentration within the reference range.

Chronic neuropathic pain. Mechanisms, diagnosis, and treatment

BACKGROUND

The management of chronic pain represents a significant public health issue in the United States. It is both costly to our health care system and devastating to the patient's quality of life. The need to improve pain outcomes is reflected by the congressional declaration of the present decade as the "Decade of Pain Control and Research," and the acknowledgment in January 2001 of pain as the "fifth vital sign" by the Joint Commission of Healthcare Organizations.

REVIEW SUMMARY

At present, therapeutic options are largely limited to drugs approved for other conditions, including anticonvulsants, antidepressants, antiarrhythmics, and opioids. However, treatment based on the underlying disease state (eg, postherpetic neuralgia, diabetic neuropathy) may be less than optimal, in that 2 patients with the same neuropathic pain syndrome may have different symptomatology and thus respond differently to the same treatment. Increases in our understanding of the function of the neurologic system over the last few years have led to new insights into the mechanisms underlying pain symptoms, especially chronic and neuropathic pain.

CONCLUSIONS

The rapidly evolving symptom- and mechanism-based approach to the treatment of neuropathic pain holds promise for improving the quality of life of our patients with neuropathic pain.

Pharmacological strategies in relieving neuropathic pain

The pharmacological treatment of neuropathic pain relies, to a large extent, on drugs belonging to a small number of defined classes. Opioids, tricyclic antidepressants, antiepileptic drugs and membrane stabilisers form the current basis of treatment. Varying levels of evidence support the use of individual members of these classes and overall show no indication that one class of drug, or individual drug has universal effectiveness. More refined knowledge of the modes of action of these agents used to treat neuropathic pain should lead to a more logical approach to the management of this difficult series of conditions. A number of drugs currently licensed for a different indication have recently had an analgesic effect in neuropathic pain attributed to them. In addition, a number of novel compounds are undergoing investigation and provide hope of dicovering more efficacious treatment options in the future.

Lamotrigine for intractable sciatica: correlation between dose, plasma concentration and analgesia

An open trial was conducted to study the potential efficacy of the antiepileptic agent lamotrigine in relieving the sciatic pain and the relationship between lamotrigine dosage, plasma concentration and the clinical response. Subsequent to a 1 week washout period from previous analgesics, lamotrigine dose was titrated on a weekly basis from 25 to 400mg/day and was maintained at that dose for additional 4 weeks. Spontaneous pain, the Short Form McGill Pain Questionnaire (SFMPQ), the Straight Leg Raise (SLR) test, and range of motion of the lumbar spine (leaning foreword, to the affected side) were used to assess lamotrigine efficacy. Lamotrigine plasma concentration was tested at the end of each week during the titration period and at the end of the study. Fourteen patients were enrolled in the study. All outcome measurers improved compared to baseline during the titration period, but reached a statistically significant level of improvement only at the 400mg dose. A linear correlation was found between mean lamotrigine dose, mean plasma concentration and mean weekly spontaneous pain, mean SLR and mean bending the affected side, but not with the SFMPQ score. Study results suggest lamotrigine is a potentially effective and safe compound for the treatment of painful lumbar radiculopathy, and that it is likely to act in a dose- and plasma concentration-dependent fashion.

Lamotrigine monotherapy for control of neuralgia after nerve section

BACKGROUND

We present six patients treated only with the new-generation anticonvulsant lamotrigine to define its sole effect on neuralgia after nerve section.

METHODS

Previous surgical or pharmacological attempts failed to relieve this neuropathic pain in our patients. Before initiation of lamotrigine therapy, patients reported spontaneous and touch-evoked shooting pain followed by periods of burning pain. No breakthrough medication was needed during the maintenance phase of 1-23 months. Data were acquired by a pain diary on a weekly basis.

RESULTS

With 75-300 mg of lamotrigine per day, the burning and shooting pain intensity was relieved by 33-100%. Most obviously, the attack frequency of the shooting pain was reduced by 80-100%. No adverse effects were observed.

CONCLUSION

We conclude that lamotrigine may be beneficial in the treatment of neuralgia after nerve section following the failure of previous pharmacological or surgical attempts.

Drug interactions with patient-controlled analgesia

Patient-controlled analgesia (PCA) has become standard procedure in the clinical treatment of pain. Its widespread use in patients with all kinds of diseases opens a variety of possible interactions between analgesics used for PCA and other drugs that might be administered concomitantly to the patient. Many of these drug interactions are of little clinical importance. However, some drug interactions have been reported to result in serious clinical problems. Drug interactions can either predominantly affect the pharmacokinetics or pharmacodynamics of the drug. Most important pharmacokinetic drug interactions occur at the level of drug metabolism or protein binding. Acceleration of methadone metabolism caused by cytochrome P450 (CYP) 3A4 induction by antiretroviral drugs or rifampicin (rifampin) has caused methadone withdrawal symptoms. Lack of morphine formation from codeine as a result of CYP2D6 inhibition by quinidine results in an almost complete loss of the analgesic effects of codeine. Alterations of methadone protein binding caused by an inhibition of alpha1-acid glycoprotein synthesis by alkylating substances are another possibility for predominantly pharmacokinetically based drug interactions during PCA. Furthermore, inhibition of P-glycoprotein by anticancer drugs could result in altered transmembrane transport of morphine, methadone or fentanyl, although this has not been shown to be of clinical relevance. Synergistic effects of systemically administered opioids with spinally or topically delivered opioids or anaesthetics have been reported frequently. The same is true for the opioid-sparing effects of coadministered non-opioid analgesics. Antidepressants, anticonvulsants or alpha2-adrenoreceptor agonists have also been shown to exert additive analgesic effects when administered together with an opioid. Inconsistent findings, however, are reported regarding the treatment of patients with opioid-induced nausea and sedation, since coadministration of antiemetics either increased or decreased the respective adverse effects or revealed additional unwanted drug effects.

Adjunctive agents in the management of chronic pain

Chronic pain syndromes include cancer-related pain, postherpetic neuralgia, painful diabetic neuropathy, and central poststroke pain and are common in the elderly. Adjunctive (or adjuvant) analgesics, defined as drugs that do not contain acetaminophen and those not classified as nonsteroidal antiinflammatory or opioid agents, play a role in the management of chronic pain. The term "adjunctive" (or "adjuvant") is a misnomer as several of these agents may constitute first-line therapy for many chronic pain syndromes. Tricyclic antidepressants have formed the backbone of therapy for chronic neuropathic pain for years. However, the difficulty with using agents of this class, due to their clinically significant adverse-event potential, has led to the evaluation of other agents, most notably, the antiepileptic drugs. The most useful are gabapentin, carbamazepine, and lamotrigine. In selected patients, baclofen, mexiletine, and clonidine may be useful as well. Cancer-related pain may respond substantially to corticosteroids, and pain associated with bone metastases to parenteral bisphosphonates and strontium. Practitioners should consider these alternative agents when treating chronic pain.

Lamotrigine reduces painful diabetic neuropathy: a randomized, controlled study

OBJECTIVE

To study the efficacy of lamotrigine in relieving the pain associated with diabetic neuropathy.

METHODS

The authors randomly assigned 59 patients to receive either lamotrigine (titrated from 25 to 400 mg/day) or placebo over a 6-week period. Primary outcome measure was self-recording of pain intensity twice daily with a 0 to 10 numerical pain scale (NPS). Secondary efficacy measures included daily consumption of rescue analgesics, the McGill Pain Questionnaire (MPQ), the Beck Depression Inventory (BDI), the Pain Disability Index (PDI), and global assessment of efficacy and tolerability.

RESULTS

Twenty-four of 29 patients (83%) receiving lamotrigine and 22 of 30 (73%) patients receiving placebo completed the study. Daily NPS in the lamotrigine-treated group was reduced from 6.4 +/- 0.1 to 4.2 +/- 0.1 and in the control group from 6.5 +/- 0.1 to 5.3 +/- 0.1 (p < 0.001 for lamotrigine doses of 200, 300, and 400 mg). The results of the MPQ, PDI, and BDI remained unchanged in both groups. The global assessment of efficacy favored lamotrigine treatment over placebo, and the adverse events profile was similar in both groups.

CONCLUSIONS

Lamotrigine is effective and safe in relieving the pain associated with diabetic neuropathy.

Non-opioid actions of lamotrigine within the rat dorsal horn after inflammation and neuropathic nerve damage

Some opioid-resistant pain conditions can be alleviated by voltage-dependent Na(+) channel blockers such as lamotrigine. The mu-opioid-receptor agonist morphine can modulate cation entry into cells to affect overall cellular excitability, an effect which can in turn be endogenously antagonised by the neuropeptide cholecystokinin (CCK). However, lamotrigine may also modulate cellular excitability by non-specifically blocking voltage-dependent ion channels. We have looked for interactions of lamotrigine with the opioid/CCK pathway within the spinal dorsal horn, to rule out the possibility that lamotrigine may attenuate nociceptive responses via actions on this pathway. Both lamotrigine and the mu-opioid agonist DAMGO inhibited mustard oil-evoked cell firing by approximately 50% compared with control levels. Co-application of CCK8S reversed DAMGO-, but not lamotrigine-induced inhibition of cell firing and this reversal was prevented with the selective CCK(B) receptor antagonist PD 135158. Although lamotrigine inhibited both brush- and cold-evoked cell firing in neuropathic animals, lamotrigine inhibition of mustard oil-evoked cell firing in the same animals was not significantly greater than that observed in controls. These results suggest that the antinociceptive properties of lamotrigine within the spinal dorsal horn are unlikely to be mediated via interactions with the opioid/CCK pathway.