Gabapentinoids and Neuropathic Pain: Evaluation of the Quality of Randomised Controlled Trials: An Umbrella Review.

Off-Label Use of Gabapentinoids: A New Paradigm

This review is an update of a review published in 2011, itself a major update of previous reviews published in 2005 and 2000, investigating the effects of gabapentin in chronic neuropathic pain (pain due to nerve damage). Antiepileptic drugs are used to manage chronic neuropathic pain and fibromyalgia. To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain and fibromyalgia. We identified randomised trials of gabapentin for chronic neuropathic pain or fibromyalgia by searching the databases MEDLINE (1966 to March 2014), EMBASE (1980 to 2014 week 10), and CENTRAL in The Cochrane Library (Issue 3 of 12, 2014). We obtained clinical trial reports and synopses of published and unpublished studies from Internet sources, and searched Clinicaltrials.gov. Searches were run originally in 2011 and the date of the most recent search was 17 March 2014. Randomised, double-blind studies reporting the analgesic and adverse effects of gabapentin in neuropathic pain or fibromyalgia with assessment of pain intensity, pain relief, or both, using validated scales. Participants were adults. Three review authors independently extracted efficacy and adverse event data, examined issues of study quality, and assessed risk of bias. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, 8 to 12 weeks duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that were considered very likely to be biased or used outcomes of limited clinical utility, or both.For efficacy, we calculated the number needed to treat to benefit (NNT), concentrating on at least 50% pain intensity reduction, and Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT) definitions of at least moderate and substantial benefit. For harm we calculated number needed to treat for harm (NNH) for adverse effects and withdrawal. Meta-analysis was undertaken using a fixed-effect model. We emphasised differences between conditions now defined as neuropathic pain, and other conditions like masticatory pain, complex regional painsyndrome type 1 (CRPS-1), and fibromyalgia. Seven new studies with 1919 participants were added. Another report (147 participants) provided results for a study already included, but which previously had no usable data. A further report (170 participants) used an experimental formulation of intrathecal gabapentin. Thirty-seven studies (5633 participants) studied oral gabapentin at daily doses of 1200 mg or more in 12 chronic pain conditions; 84% of participants were in studies of postherpetic neuralgia, painful diabetic neuropathy or mixed neuropathic pain. There was no first tier evidence.Second tier evidence for the outcome of at least 50% pain intensity reduction, considered valuable by patients with chronic pain, showed that gabapentin was significantly better than placebo in postherpetic neuralgia (34% gabapentin versus 21% placebo; NNT 8.0, 95% CI 6.0 to 12) and painful diabetic neuropathy (38% versus 21%, NNT 5.9, 95% CI 4.6 to 8.3). There was insufficient information in other pain conditions to reach any reliable conclusion. There was no obvious difference between standard gabapentin formulations and recently-introduced extended-release or gastro-retentive formulations, or between different doses of gabapentin.Adverse events occurred significantly more often with gabapentin. Persons taking gabapentin could expect to have at least one adverse event (62%), withdraw because of an adverse event (11%), suffer dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (9%). Serious adverse events (3%) were no more common than with placebo.There were insufficient data for direct comparisons with other active treatments, and only third tier evidence for other painful conditions. There was no top tier evidence that was unequivocally unbiased. Second tier evidence, with potentially important residual biases, showed that gabapentin at doses of 1200 mg or more was effective for some people with some painful neuropathic pain conditions. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. About 35% achieved this degree of pain relief with gabapentin, compared with 21% for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief. Results might vary between different neuropathic pain conditions, and the amount of evidence for gabapentin in neuropathic pain conditions except postherpetic neuralgia and painful diabetic neuropathy, and in fibromyalgia, is very limited.The levels of efficacy found for gabapentin are consistent with those found for other drug therapies in postherpetic neuralgia and painful diabetic neuropathy.

Antiepileptic drugs have been used for treating different types of neuropathic pain, and sometimes fibromyalgia. Our understanding of quality standards in chronic pain trials has improved to include new sources of potential bias. Individual Cochrane reviews using these new standards have assessed individual antiepileptic drugs. An early review from this group, originally published in 1998, was titled 'Anticonvulsants for acute and chronic pain'. This overview now covers the neuropathic pain aspect of that original review, which was withdrawn in 2009. To provide an overview of the relative analgesic efficacy of antiepileptic drugs that have been compared with placebo in neuropathic pain and fibromyalgia, and to report on adverse events associated with their use. We included reviews published in theCochrane Database of Systematic Reviews up to August 2013 (Issue 7). We extracted information from each review on measures of efficacy and harm, and methodological details concerning the number of participants, the duration of studies, and the imputation methods used, in order to judge potential biases in available data.We analysed efficacy data for each painful condition in three tiers, according to outcome and freedom from known sources of bias. The first tier met current best standards - at least 50% pain intensity reduction over baseline (or its equivalent), without the use of last observation carried forward (LOCF) for dropouts, an intention-to-treat (ITT) analysis, in parallel group studies with at least 200 participants lasting eight weeks or more. The second tier used data from at least 200 participants where one or more of the above conditions were not met. The third tier of evidence related to data from fewer than 200 participants, or with several important methodological problems that limited interpretation. No studies reported top tier results.For gabapentin and pregabalin only we found reasonably good second tier evidence for efficacy in painful diabetic neuropathy and postherpetic neuralgia. In addition, for pregabalin, we found evidence of efficacy in central neuropathic pain and fibromyalgia. Point estimates of numbers needed to treat for an additional beneficial effect (NNTs) were in the range of 4 to 10 for the important outcome of pain intensity reduction over baseline of 50% or more.For other antiepileptic drugs there was no evidence (clonazepam, phenytoin), so little evidence that no sensible judgement could be made about efficacy (valproic acid), low quality evidence likely to be subject to a number of biases overestimating efficacy (carbamazepine), or reasonable quality evidence indicating little or no effect (lamotrigine, oxcarbazepine, topiramate). Lacosamide recorded such a trivial statistical superiority over placebo that it was unreliable to conclude that it had any efficacy where there was possible substantial bias.Any benefits of treatment came with a high risk of adverse events and withdrawal because of adverse events, but serious adverse events were not significantly raised, except with oxcarbazepine. Clinical trial evidence supported the use of only gabapentin and pregabalin in some neuropathic pain conditions (painful diabetic neuropathy, postherpetic neuralgia, and central neuropathic pain) and fibromyalgia. Only a minority of people achieved acceptably good pain relief with either drug, but it is known that quality of life and function improved markedly with the outcome of at least 50% pain intensity reduction. For other antiepileptic drugs there was no evidence, insufficient evidence, or evidence of a lack of effect; this included carbamazepine. Evidence from clinical practice and experience is that some patients can achieve good results with antiepileptics other than gabapentin or pregabalin.There is no firm evidence to answer the important pragmatic questions about which patients should have which drug, and in which order the drugs should be used. There is a clinical effectiveness research agenda to provide evidence about strategies rather than interventions, to produce the overall best results in a population, in the shortest time, and at the lowest cost to healthcare providers.

There was insufficient evidence to determine whether nutmeg or St John's wort has any meaningful efficacy in neuropathic pain conditions.The quality of the current evidence raises serious uncertainties about the estimates of effect observed, therefore, we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

This review found little evidence to support the effectiveness of oxcarbazepine in painful diabetic neuropathy, neuropathic pain from radiculopathy and a mixture of neuropathies. Some very-low-quality evidence suggests efficacy but small trials, low event rates, heterogeneity in some measures and a high risk of publication bias means that we have very low confidence in the measures of effect. Adverse effects, serious adverse effects and adverse effects leading to discontinuation are probably more common with oxcarbazepine than placebo; however, the numbers of participants and event rates are low. More well-designed, multicentre RCTs investigating oxcarbazepine for various types of neuropathic pain are needed, and selective publication of studies or data should be avoided.

Gabapentin is commonly used to treat neuropathic pain (pain due to nerve damage). This review updates a review published in 2014, and previous reviews published in 2011, 2005 and 2000. To assess the analgesic efficacy and adverse effects of gabapentin in chronic neuropathic pain in adults. For this update we searched CENTRAL), MEDLINE, and Embase for randomised controlled trials from January 2014 to January 2017. We also searched the reference lists of retrieved studies and reviews, and online clinical trials registries. We included randomised, double-blind trials of two weeks' duration or longer, comparing gabapentin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment. Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with substantial pain relief (at least 50% pain relief over baseline or very much improved on Patient Global Impression of Change scale (PGIC)), or moderate pain relief (at least 30% pain relief over baseline or much or very much improved on PGIC). We performed a pooled analysis for any substantial or moderate benefit. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio (RR) and number needed to treat for an additional beneficial outcome (NNT) or harmful outcome (NNH). We assessed the quality of the evidence using GRADE and created 'Summary of findings' tables. We included four new studies (530 participants), and excluded three previously included studies (126 participants). In all, 37 studies provided information on 5914 participants. Most studies used oral gabapentin or gabapentin encarbil at doses of 1200 mg or more daily in different neuropathic pain conditions, predominantly postherpetic neuralgia and painful diabetic neuropathy. Study duration was typically four to 12 weeks. Not all studies reported important outcomes of interest. High risk of bias occurred mainly due to small size (especially in cross-over studies), and handling of data after study withdrawal.In postherpetic neuralgia, more participants (32%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (17%) (RR 1.8 (95% CI 1.5 to 2.1); NNT 6.7 (5.4 to 8.7); 8 studies, 2260 participants, moderate-quality evidence). More participants (46%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (25%) (RR 1.8 (95% CI 1.6 to 2.0); NNT 4.8 (4.1 to 6.0); 8 studies, 2260 participants, moderate-quality evidence).In painful diabetic neuropathy, more participants (38%) had substantial benefit (at least 50% pain relief or PGIC very much improved) with gabapentin at 1200 mg daily or greater than with placebo (21%) (RR 1.9 (95% CI 1.5 to 2.3); NNT 5.9 (4.6 to 8.3); 6 studies, 1277 participants, moderate-quality evidence). More participants (52%) had moderate benefit (at least 30% pain relief or PGIC much or very much improved) with gabapentin at 1200 mg daily or greater than with placebo (37%) (RR 1.4 (95% CI 1.3 to 1.6); NNT 6.6 (4.9 to 9.9); 7 studies, 1439 participants, moderate-quality evidence).For all conditions combined, adverse event withdrawals were more common with gabapentin (11%) than with placebo (8.2%) (RR 1.4 (95% CI 1.1 to 1.7); NNH 30 (20 to 65); 22 studies, 4346 participants, high-quality evidence). Serious adverse events were no more common with gabapentin (3.2%) than with placebo (2.8%) (RR 1.2 (95% CI 0.8 to 1.7); 19 studies, 3948 participants, moderate-quality evidence); there were eight deaths (very low-quality evidence). Participants experiencing at least one adverse event were more common with gabapentin (63%) than with placebo (49%) (RR 1.3 (95% CI 1.2 to 1.4); NNH 7.5 (6.1 to 9.6); 18 studies, 4279 participants, moderate-quality evidence). Individual adverse events occurred significantly more often with gabapentin. Participants taking gabapentin experienced dizziness (19%), somnolence (14%), peripheral oedema (7%), and gait disturbance (14%). Gabapentin at doses of 1800 mg to 3600 mg daily (1200 mg to 3600 mg gabapentin encarbil) can provide good levels of pain relief to some people with postherpetic neuralgia and peripheral diabetic neuropathy. Evidence for other types of neuropathic pain is very limited. The outcome of at least 50% pain intensity reduction is regarded as a useful outcome of treatment by patients, and the achievement of this degree of pain relief is associated with important beneficial effects on sleep interference, fatigue, and depression, as well as quality of life, function, and work. Around 3 or 4 out of 10 participants achieved this degree of pain relief with gabapentin, compared with 1 or 2 out of 10 for placebo. Over half of those treated with gabapentin will not have worthwhile pain relief but may experience adverse events. Conclusions have not changed since the previous update of this review.

Neuropathic pain is a persistent pain condition that develops secondary to nerve injury. The two most common types of peripheral neuropathic pain are post-herpetic neuralgia (PHN) and painful diabetic neuropathy (PDN). Amitriptyline, nortriptyline, desipramine and imipramine are TCAs that have been shown to be effective for the symptomatic relief of PHN and PDN. Serotonin noradrenaline reuptake inhibitors (SNRIs) such as venlafaxine and duloxetine have been shown to be very promising for the treatment of PDN with fewer adverse effects than TCAs. Selective serotonin reuptake inhibitors (SSRIs) were shown in a number of studies to have some efficacy in relieving PDN-related pain, yet other studies of the SSRIs have demonstrated conflicting outcomes. Most of the older antiepileptic studies were performed in patients with PDN; consequently, little is known about the efficacy of these drugs in patients with PHN. Carbamazepine, phenytoin and valproic acid were shown to be effective in ameliorating PDN-related pain. Other antiepileptic agents, including lamotrigine, oxcarbazepine and topiramate, have demonstrated some beneficial effects for the treatment of PDN, although they were also found to be ineffective in some PDN studies. alpha2delta Ligands such as gabapentin and pregabalin have been proven to be effective for the treatment of PHN and PDN in a number of large placebo-controlled trials. These drugs are useful not only in relieving pain but also in improving quality of life. Although the use of opioids for the treatment of neuropathic pain is controversial, a number of studies support the efficacy and safety of opioids in the treatment of neuropathic pain. Of these, oxycodone and tramadol have been shown to be superior to placebo for the treatment of PHN and PDN. A number of small studies have shown that dextromethorphan was effective in patients with PDN but not in patients with PHN. Topical agents such as lidocaine 5% patches and topical capsaicin are useful in ameliorating pain in patients with PHN but these agents are unsatisfactory for use as a sole agent. Although a number of drug treatments are available for the symptomatic relief of neuropathic pain symptoms, these agents do not provide satisfactory relief in all patients. For these patients, other treatment alternatives such as combination drug therapy that produces pain relief via distinctly different mechanisms may be successful. The purpose of this review is to compare the efficacy and limitations of currently available pharmacological treatments for the symptomatic relief of PHN and PDN, and to discuss the potential of combination therapy in PHN and PDN.

This review is one of a series on drugs used to treat neuropathic pain and fibromyalgia. These conditions are estimated to affect 3 to 10% of adults, and are difficult to treat. Although they probably have different aetiologies, neuropathic pain and fibromyalgia can respond to the same therapies. There have been substantial changes in the standards of evidence considered necessary for assessment of interventions to treat chronic pain, to provide data that are more robust and clinically relevant. Oxycodone is a strong opioid agonist widely used to manage severe pain; this review assesses evidence for oxycodone using current standards of evidence designed to reduce bias. To assess the analgesic efficacy and adverse events of oxycodone for chronic neuropathic pain and fibromyalgia. On 6 November 2013, we searched CENTRAL, MEDLINE and EMBASE databases. We reviewed the bibliographies of all included studies and of reviews, and also searched two clinical trial databases, ClinicalTrials.gov and the World Health Organisation (WHO) International Clinical Trials Registry Platform, to identify additional published or unpublished data. We included randomised controlled trials (RCTs) with double-blind assessment of participant outcomes following two weeks of treatment or longer (although the emphasis of the review was on studies of eight weeks or longer) that used a placebo or active comparator. Two review authors independently extracted efficacy and adverse event data, examined issues of study quality, and assessed risk of bias. We performed analysis using three tiers of evidence. First tier evidence was derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison, eight to 12 weeks duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both. We included three studies with 254 participants; 204 had painful diabetic neuropathy and 50 postherpetic neuralgia. Study size ranged from 45 to 159 participants. Two studies used a cross-over design and one a parallel group design; study duration was four or six weeks. Controlled release oxycodone (oxycodone CR) was used in all three studies, with doses titrated up to a maximum of between 60 and 120 mg daily; mean doses achieved ranged between 37 and 45 mg daily. All studies used a placebo comparator, although in one study, an active placebo (benztropine) was used. All studies had one or more sources of potential major bias.No study reported the proportion of participants experiencing at least 50% pain relief or who were very much improved, while one reported the proportion with at least 30% pain relief, two reported at least moderate pain relief, and one reported the number of participants who considered treatment to be moderately effective. No study provided first or second tier evidence for an efficacy outcome. Third tier evidence indicated greater pain intensity reduction and better patient satisfaction with oxycodone than with placebo in all three studies, but such evidence was derived mainly from group mean data, with last observation carried forward (LOCF) imputation or completer analysis, in small studies lasting less than eight weeks (very low quality evidence).Adverse events were more common with oxycodone CR than with placebo. At least one adverse event was experienced by 86% of participants taking oxycodone CR and 63% taking placebo, and the number needed to treat for an additional harmful effect (NNH) was 4.3. The effect of oxycodone on serious adverse events reported was uncertain in comparison with placebo (oxycodone 3.4% versus placebo: 7.0%; RR 0.48 (95% confidence interval (CI) 0.18 to 1.23; very low quality evidence); one death was reported with oxycodone CR, but was not attributed to treatment. Adverse event withdrawals did not differ significantly between groups, occurring in 11% of participants with oxycodone CR and 6.4% with placebo (RR 1.69 (0.83 to 3.43); very low quality evidence). Withdrawals due to lack of efficacy were less frequent with oxycodone CR (1.1%) than placebo (11%), with an NNT to prevent one withdrawal of 10 (RR 0.12 (0.03 to 0.45); very low quality evidence).We found no relevant studies in chronic neuropathic pain conditions other than painful diabetic neuropathy or postherpetic neuralgia, or in fibromyalgia. No convincing, unbiased evidence suggests that oxycodone (as oxycodone CR) is of value in treating people with painful diabetic neuropathy or postherpetic neuralgia. There is no evidence at all for other neuropathic pain conditions, or for fibromyalgia. Adverse events typical of opioids appear to be common.

The World Health Organisation estimated that in the year 2000, 150 million people had diabetes mellitus, and it is predicted that this number will rise to 366 million by the year 2030.[1][1] Neuropathy is a common complication of diabetes and is characterised by a progressive loss of peripheral

This is an update of an earlier review that considered both neuropathic pain and fibromyalgia (Issue 6, 2014), which has now been split into separate reviews for the two conditions. This review considers neuropathic pain only.Opioid drugs, including oxycodone, are commonly used to treat neuropathic pain, and are considered effective by some professionals. Most reviews have examined all opioids together. This review sought evidence specifically for oxycodone, at any dose, and by any route of administration. Separate reviews consider other opioids. To assess the analgesic efficacy and adverse events of oxycodone for chronic neuropathic pain in adults. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE from inception to 6 November 2013 for the original review and from January 2013 to 21 December 2015 for this update. We also searched the reference lists of retrieved studies and reviews, and two online clinical trial registries. This update differs from the earlier review in that we have included studies using oxycodone in combination with naloxone, and oxycodone used as add-on treatment to stable, but inadequate, treatment with another class of drug. We included randomised, double-blind studies of two weeks' duration or longer, comparing any dose or formulation of oxycodone with placebo or another active treatment in chronic neuropathic pain. Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. Where pooled analysis was possible, we used dichotomous data to calculate risk ratio and numbers needed to treat for one additional event, using standard methods.We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table. The updated searches identified one additional published study, and one clinical trial registry report. We included five studies reporting on 687 participants; 637 had painful diabetic neuropathy and 50 had postherpetic neuralgia. Two studies used a cross-over design and three used a parallel group design; all studies used a placebo comparator, although one study used an active placebo (benztropine). Modified-release oxycodone (oxycodone MR) was titrated to effect and tolerability. One study used a fixed dose combination of oxycodone MR and naloxone. Two studies added oxycodone therapy to ongoing, stable treatment with either pregabalin or gabapentin. All studies had one or more sources of potential major bias.No study reported the proportion of participants experiencing 'substantial benefit' (at least 50% pain relief or who were very much improved). Three studies (537 participants) in painful diabetic neuropathy reported outcomes equivalent to 'moderate benefit' (at least 30% pain relief or who were much or very much improved), which was experienced by 44% of participants with oxycodone and 27% with placebo (number needed to treat for one additional beneficial outcome (NNT) 5.7).All studies reported group mean pain scores at the end of treatment. Three studies reported a greater pain intensity reduction and better patient satisfaction with oxycodone MR alone than with placebo. There was a similar result in the study adding oxycodone MR to stable, ongoing gabapentin, but adding oxycodone MR plus naloxone to stable, ongoing pregabalin did not show any additional effect.More participants experienced adverse events with oxycodone MR alone (86%) than with placebo (63%); the number needed to treat for an additional harmful outcome (NNH) was 4.3. Serious adverse events (oxycodone 3.4%, placebo 7.0%) and adverse event withdrawals (oxycodone 11%, placebo 6.4%) were not significantly different between groups. Withdrawals due to lack of efficacy were less frequent with oxycodone MR (1.1%) than placebo (11%), with a number needed to treat to prevent one withdrawal of 10. The add-on studies reported similar results.We downgraded the quality of the evidence to very low for all outcomes, due to limitations in the study methods, heterogeneity in the pain condition and study methods, and sparse data. There was only very low quality evidence that oxycodone (as oxycodone MR) is of value in the treatment of painful diabetic neuropathy or postherpetic neuralgia. There was no evidence for other neuropathic pain conditions. Adverse events typical of opioids appeared to be common.

Gabapentin was initially developed as an antiepileptic drug but was later discovered to be an effective treatment of neuropathic pain. Gabapentin has been successfully used for the treatment of multiple neuropathic pain syndromes such as diabetic neuropathy and postherpetic neuralgia. However, limited data exist about its efficacy for other pain syndromes. The objective of the current review is to describe, from the literature, the role of gabapentin for the treatment of cancer-related pain syndromes. Studies were identified by searching the PubMed electronic databases. Additional review articles and article reference lists were used to identify other studies. Recent studies showed effectiveness of gabapentin in improving the pain control in patients with neuropathic cancer pain, already treated with opiates. Moreover, gabapentin appeared promising in reducing the need for high total doses of opioids and avoiding unplanned treatment interruptions for patients with head and neck malignancies treated with radiotherapy or concurrent chemoradiotherapy. Furthermore, the combination of gabapentin and morphine has been shown to effect better pain relief at lower doses of each drug when compared with gabapentin or morphine alone in patients with painful diabetic neuropathy or postherpetic neuralgia. The combination of both drugs was associated with a beneficial effect on pain-related interference with daily activity, mood, sleep and quality of life. Given the significant benefits of gabapentin and the combination of gabapentin with opioids for the treatment of neuropathic pain, randomized clinical trials are needed to establish the role of these analgesic regimens for the treatment of neuropathic cancer pain.

Impact of postherpetic neuralgia and painful diabetic peripheral neuropathy on healthcare costs

Topical analgesics: Lidocaine patch 5% effectively treats neuropathic pain qualities in three chronic pain states: results of a 2-week, prospective, open-label trial

Gabapentin

Предпосылки. Прегабалин является габапентиноидом нового поколения с улучшенными фармакологическими свойствами. Нейропатическая боль — актуальная проблема современной медицины, в отдельных случаях трудно поддающаяся лечению. В связи с этим цель настоящего обзора сводится к оценке эффективности прегабалина при лечении периферической и центральной нейропатической боли в клинических исследованиях высокого уровня. Материалы и методы. В настоящий обзор были включены рандомизированные контролируемые исследования (РКИ) с двойным слепым дизайном и их метаанализы. Результаты. В выполненных исследованиях была подтверждена обезболивающая активность прегабалина у пациентов с нейропатической болью: при болевой диабетической нейропатии (9 РКИ), постгерпетической невралгии (4 РКИ), центральной нейропатической боли вследствие повреждения спинного мозга (3 РКИ), посттравматической периферической нейропатической боли, включая хроническую послеоперационную боль (2 РКИ), нейропатической боли при раке (2 РКИ). Требует дальнейшего уточнения эффективность препарата при центральной нейропатической боли вследствие повреждения головного мозга и хронической боли в нижней части спины (в обоих случаях по 2 РКИ с результатами «есть эффект/нет эффекта»). Дополнительно у пациентов с нейропатической болью прегабалин уменьшал нарушение сна, улучшал общее состояние и качество жизни. Кроме того, уменьшалась выраженность аллодинии при постгерпетической невралгии, тревоги при центральной нейропатической боли, снижалась потребность в морфине при нейропатической боли вследствие рака и выраженность обусловленных им запоров, усиливались эффекты нестероидных противовоспалительных средств при хронической боли в нижней части спины. Эффективность прегабалина у пожилых пациентов была сравнима с таковой у более молодых пациентов. Прегабалин назначают в дозе 75 мг/день в 1 прием или в дозе 150 мг/день в 2 приема. Затем дозу постепенно увеличивают до 300–600 мг/день таким образом, чтобы соотношение эффективность/безопасность было оптимальным. Обезболивающий эффект начинает появляться в первую неделю терапии, в зависимости от выбранного дозового режима и тяжести патологии. Побочные эффекты при лечении прегабалином носят легкий и умеренный характер, часто самостоятельно исчезают по ходу лечения. Наиболее частыми побочными эффектами были головокружение (прегабалин — 26,3 %, плацебо — 9 %), сонливость (16,8 и 7 % соответственно) и периферические отеки (8,9 и 0,4 % соответственно). Несмотря на то что частота побочных эффектов для прегабалина превышала таковую для плацебо и в ряде случаев приводила к прекращению приема препарата, авторы исследований сообщают о хорошей переносимости прегабалина. Выводы. Результаты исследований высокого уровня подтверждают эффективность прегабалина в лечении пациентов с периферической и центральной нейропатической болью. Для препарата была характерна хорошая переносимость.