Prolonged-release oxycodone enhances the effects of existing gabapentin therapy in painful diabetic neuropathy patients

BACKGROUND

Neuropathic pain remains one of the most challenging pain syndromes; under-diagnosed, poorly managed and associated with significant co-morbidity. With standard therapeutic treatments, responders rarely exceed 50% pain relief and the majority suffer from residual pain. Titration to optimum dose is often limited by dose-related adverse events.

AIMS

This randomized, double-blind, placebo-controlled study assessed the potential benefit of adding oxycodone (OxyContin tablets) to gabapentin. The primary endpoint was to evaluate the analgesic efficacy of co-administration of gabapentin and prolonged-release oxycodone, whilst also evaluating the use of escape medication, sleep quality and global assessment of pain.

METHODS

Three hundred and thirty eight patients with moderate to severe painful diabetic neuropathy despite receiving their maximum tolerated dose of gabapentin, had oral prolonged-release oxycodone or placebo tablets added to their therapy for up to 12 weeks.

RESULTS

Oxycodone-gabapentin reduced pain score by 33% from baseline to end of treatment. The overall treatment effect was greater with oxycodone-gabapentin than with placebo-gabapentin (P = 0.007). Oxycodone-gabapentin also significantly improved pain relief vs gabapentin alone (P = 0.003). Oxycodone-gabapentin co-administration was associated with less escape medication use (P = 0.03) and fewer nights of disturbed sleep (P < 0.05). Discontinuations due to lack of therapeutic effect were much lower (14% vs 54%) with oxycodone-gabapentin. The commonly seen opiate-induced adverse events were not exacerbated by the combination of oxycodone and gabapentin.

CONCLUSIONS

This study provides the first evidence that co-administration of prolonged-release oxycodone and existing gabapentin therapy has a clinically meaningful effect in painful diabetic neuropathy.

Pregabalin add-on for drug-resistant partial epilepsy

BACKGROUND

Epilepsy is a common chronic neurological disease with an estimated prevalence of 1% in the United Kingdom. Approximately a third of these people continue to have seizures despite drug treatment. In order to try to improve outcomes a number of new antiepileptic drugs have been developed and pregabalin is one of these.

OBJECTIVES

To summarize evidence from randomized, controlled trials regarding the efficacy and tolerability of pregabalin when used as an add-on antiepileptic drug in treatment-resistant partial epilepsy.

SEARCH STRATEGY

We searched the Cochrane Epilepsy Group Specialized Register (July 2007), The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2007), Medline (1966 to March 2007) and contacted Pfizer Inc (the manufacturers of pregabalin) to identify published, unpublished, and ongoing trials.

SELECTION CRITERIA

We included randomized controlled double-blind trials comparing pregabalin with placebo for people with drug-refractory partial epilepsy. Outcomes included 50% or greater reduction in seizure frequency, treatment withdrawal for any reason, treatment withdrawal for adverse events, and nature of adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors (DL and AGM) independently selected and assessed suitable trials and extracted data. Primary analyses were by intention-to-treat (ITT). Results are presented as relative risks (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Four suitable trials (1397 participants) were identified and included in the analysis. Trials tested doses of pregabalin ranging from 50 mg to 600 mg per day. For the primary outcome, 50% or higher seizure reduction was significantly more likely in patients randomized to pregabalin than to placebo (RR 3.56, 95% CI 2.60 to 4.87). A dose response analysis suggested increasing effect with increasing dose. Pregabalin was not significantly associated with seizure freedom (RR 2.73, 95% CI 0.72 to 10.33). Patients were significantly more likely to have pregabalin withdrawn for any reason (RR 1.43, 95% CI 1.11 to 1.85) or for adverse effects (RR 2.47, 95% CI 1.80 to 4.17). Ataxia, dizziness, somnolence and weight gain were significantly associated with pregabalin.

AUTHORS' CONCLUSIONS

Pregabalin, when used as an add-on drug for treatment-resistant partial epilepsy, is significantly more effective than placebo at achieving a 50% or greater seizure reduction. Results demonstrate efficacy for doses from 150 mg to 600 mg per day, with no evidence for plateauing of effect at the doses tested. The trials included in this review were of short duration and longer term trials are needed to better inform clinical decision making.

Teratogenic effects of the anticonvulsant gabapentin in mice

INTRODUCTION

We aim to study and elucidate the safety profile of the antiepileptic doses of gabapentin during pregnancy, and to evaluate gabapentin-induced murine fetotoxicity at different dose levels.

METHODS

A total of 60 pregnant mice, divided into 12 groups of five mice each, were exposed to gabapentin in four different doses of 0 (control), 113, 226, or 452 mg/kg body weight per day, at three different gestational stages including early gestation (1-6 days), mid-gestation (7-12 days), and late gestation (13-17 days). The pregnant mice were euthanized on day 18 of gestation, and foetuses were examined for teratogenic manifestations. Their brains were dissected and examined for gross changes, malformations, histological changes, and quantitative protein estimation.

RESULTS

Foetal resorptions were observed in all treated groups with gabapentin administration at early gestation (1-6 days), and mid-gestation (7-12 days). On the other hand, growth retardation along with stunting in size of live foetuses were observed in all the mid-gestation (7-12 days), and late gestation (13-17 days) treated groups. Various gross malformations were observed with all the three doses (113, 226, and 452 mg/kg body weight per day) when gabapentin was administered at mid-gestation (7-12 days). The same trends were confirmed by gross and microscopic examination of brains along with quantitative protein estimation.

CONCLUSION

Gabapentin should not be prescribed during pregnancy, as no therapeutic dose of gabapentin is safe during this period as far as the foetal well-being is concerned.

A cost-utility comparison of four first-line medications in painful diabetic neuropathy

BACKGROUND

Painful diabetic neuropathy is common and adversely affects patients' quality of life and function. Several treatment options exist, but their relative efficacy and value are unknown.

OBJECTIVE

To determine the relative efficacy, costs and cost effectiveness of the first-line treatment options for painful diabetic neuropathy.

METHODS

Published and unpublished clinical trial and cross-sectional data were incorporated into a decision analytic model to estimate the net health and cost consequences of treatment for painful diabetic peripheral neuropathy over 3-month (base case), 1-month and 6-month timeframes. Efficacy was measured in QALYs, and costs were measured in $US, year 2006 values, using a US third-party payer perspective. The patients included in the model were outpatients with moderate to severe pain associated with diabetic peripheral neuropathy and no contraindications to treatment with tricyclic antidepressants. Four medications were compared: desipramine 100 mg/day, gabapentin 2400 mg/day, pregabalin 300 mg/day and duloxetine 60 mg/day.

RESULTS

Desipramine and duloxetine were both more effective and less expensive than gabapentin and pregabalin in the base-case analysis and through a wide range of sensitivity analyses. Duloxetine offered borderline value compared with desipramine in the base case ($US47,700 per QALY), but not when incorporating baseline-observation-carried-forward analyses of the clinical trial data ($US867,000 per QALY). The results were also sensitive to the probability of obtaining pain relief with duloxetine.

CONCLUSIONS

Desipramine (100 mg/day) and duloxetine (60 mg/day) appear to be more cost effective than gabapentin or pregabalin for treating painful diabetic neuropathy. The estimated value of duloxetine relative to desipramine depends on the assumptions made in the statistical analyses of clinical trial data.

Efficacy and safety of pregabalin in treatment refractory patients with various neuropathic pain entities in clinical routine

AIMS

Conventional approaches to the management of neuropathic pain (NeP) often yield unsatisfactory results. We aimed to investigate pregabalin, a gamma-aminobutyric acid (GABA)-analogue, in a wide range of pregabalin naive patients with treatment refractory NeP.

METHODS

Investigator-initiated, 4-week, open, prospective multicentre study in tertiary care. Pregabalin was prescribed at physicians' discretion based on patients' individual responses and tolerability, with or without concomitant analgesics. Consecutive patients were requested to fill in questionnaires at baseline and after 14 and 28 days with numerical pain rating scales (0, none; 10, worst possible), sleep rating scales, parts of the Brief Pain Inventory, Pain Experience Scale, Short Questionnaire on Current Burden and the SF-12 health-related quality of life scale.

RESULTS

In 55 patients, the mean pregabalin dose was 142 +/- 26 mg at day 1 and 348 +/- 161 mg at day 28. The mean pain score decreased from 6.5 +/- 1.7 to 5.5 +/- 1.9 at day 14 and to 4.9 +/- 1.8 at day 28 (-24.6%, p < 0.0001). Significant and rapid improvements were noted in the sleep interference score (p < 0.00001), Short Questionnaire on Current Burden (p < 0.01) and SF-12 (somatic score p < 0.001; psychological score p < 0.01). Pregabalin was well tolerated, and only three patients (5%) discontinued treatment prematurely.

CONCLUSIONS

Our findings suggest that pregabalin is an effective and well-tolerated drug in difficult-to-treat NeP patients under daily clinical practice conditions. A flexible dosing approach appears appropriate to ensure patient compliance and treatment success.

Gabapentin Extended-Release - Depomed: Gabapentin ER, Gabapentin Gastric Retention, Gabapentin GR

Depomed is developing an extended-release (ER) oral formulation of gabapentin, a GABA receptor agonist commonly used for the treatment of epilepsy and seizures, neuropathic pain and hot flushes. Gabapentin ER is based on the company's proprietary AcuForm drug delivery technology, which is part of the Gastric Retention (GR) family of technologies; this offers improved drug absorption and bioavailability compared with the existing immediate-release formulation of gabapentin (Neurontin), making gabapentin ER suitable for twice-daily dosing. The product is in clinical development for the treatment of postherpetic neuralgia and diabetic neuropathies in the US. Additionally, Depomed has commenced a phase II trial of gabapentin ER in postmenopausal patients with hot flushes. Depomed's AcuForm platform is based on polymer technology that provides targeted drug delivery for a variety of compounds. Following ingestion, AcuForm tablets swell and are retained for 6-8 hours in the stomach, enabling controlled and prolonged release of gabapentin to the upper intestinal tract; this extends the time of drug delivery to the small intestine for complete and safe elimination via the lower intestinal track. Gabapentin ER is available for licensing. Depomed acquired exclusive development and commercialisation rights to gabapentin ER in September 2003 via its subsidiary, Depomed Development Ltd (DDL). Depomed is not required to pay upfront license fees, but will make royalty and milestone payments to DDL upon successful commercialisation of gabapentin ER. Gabapentin ER was originally developed by DDL, a joint venture between Depomed and Elan established in January 2000 to design products using the GR family of technologies. However, in efforts to restructure joint venture relationships, Elan withdrew from operational involvement of DDL in September 2003, and Depomed has gained full ownership of DDL. Depomed sublicensed exclusive rights to a US patent (held by the University of Rochester) covering the use of gabapentin in the treatment of hot flushes from PharmaNova in October 2006. Under the agreement, Depomed paid PharmaNova an upfront fee of US dollars 500 000. PharmaNova is also entitled to milestone payments and royalties on sales of gabapentin ER in this indication only. Depomed has reported significant safety and efficacy benefits from gabapentin ER in its phase II trial. This study was initiated in February 2005 following positive results from a phase I trial in which gabapentin ER demonstrated a pharmacokinetic profile suitable for twice-daily dosing. In two pharmacokinetic studies, gabapentin ER achieved improved bioavailability at higher doses. This result supports Depomed's development of a once- or twice-daily product with potentially fewer adverse events. The basic US patents relating to gabapentin expired in 2000. Depomed holds exclusive rights to a US patent (No. 6 310 098) held by the University of Rochester covering the use of gabapentin to treat hot flushes.Additionally, Depomed was issued a US patent (No. 6 723 340) in May 2004 that covers proprietary polymer combinations (as used in AcuForm tablets) to create improved formulations of existing drugs.

Pregabalin-induced generalized myoclonic status epilepticus in patients with chronic pain

Pregabalin is often used for the treatment of chronic pain syndromes. We here describe two patients with chronic pain and pregabalin-induced myoclonic status epilepticus. Patients treated with pregabalin who experience sudden behavioral changes or mycloni should be investigated for this possible side effect, and pregabalin should be reduced or discontinued if myocloni or status epilepticus occurs.

[Efficacy and safety of gabapentin in Borderline Personality Disorder: a six-month, open-label study]

Anticonvulsants are showing to be helpful in the treatment of Borderline Personality Disorder and are widely used in clinical settings, although few studies have been published and their role in different borderline patients is not completely outlined. Gabapentin pharmacologic profile and its documented efficacy in anxiety disorders and drug abuse withdrawal were the basis for this open label multicenter six-month follow-up trial in borderline patients not enough responsive to previous therapies. DSM-IV Borderline Personality diagnosis was confirmed by the Diagnostic Interview for Borderlines-Revised. Outcome measures were changes in scores on Hamilton Anxiety Rating Scale, Young Mania Rating Scale, Beck Depression Inventory, Barratt Impulsivity Scale and Clinical Global Impression Scale of Severity and Improvement. A global improvement, especially in anxious and depressive symptomatology, was observed; no adverse events were reported. Gabapentin showed to be efficacious and safe in Borderline Personality Disorder's treatment.

Life-Threatening Status Epilepticus Following Gabapentin Administration in a Patient with Benign Adult Familial Myoclonic Epilepsy

We report the case of a 57-year-old man who experienced life-threatening myoclonic status after the administration of gabapentin. Based on familial data, the patient was determined to be a member of a previously described family with benign adult familial myoclonic epilepsy (BAFME). The myoclonic status did not respond to benzodiazepines, but resolved after discontinuing the gabapentin. As for other idiopathic generalized epilepsies, gabapentin may precipitate myoclonic status in a benign syndrome, such as BAFME, as is reported herein for the first time. A correct diagnosis and prompt discontinuation of the drug may reverse a potentially severe, life-threatening condition.

The Analgesic Effects of Preemptive Gabapentin in Patients Undergoing Surgery for Brachial Plexus Injury—A Preliminary Study

There are reports indicating that gabapentin may have place in the treatment of postoperative pain. No study has evaluated the effects of gabapentin on acute, postoperative pain in patients undergoing surgery for brachial plexus injuries. In this preliminary study, we evaluated gabapentin as preemptive analgesic for intraoperative period and during the acute postoperative period at rest and during movement. Twenty consecutive adult patients undergoing surgery for brachial plexus injury were enrolled for the study. Patients randomly received either oral gabapentin 800 mg or placebo capsules 2 hours before surgery. General anesthesia was induced and maintained with propofol, at bispectral index value between 40 and 60. Intraoperative fentanyl and propofol requirements were noted. Postoperatively, all patients were alert and pain was assessed using visual analog scale (VAS) for 24 hours, both during rest and movement. Whenever VAS score was more than 50 or on patients' demand, ketorolac 30 mg was given as rescue analgesic. The demographics, duration of surgery, and propofol consumption in both groups were comparable. Intraoperative and postoperative heart rate and mean blood pressure were also comparable. Significant difference was noted in intraoperative fentanyl consumption (P=0.03), total dose of rescue analgesic (P=0.004), and VAS score at rest and movement, between the 2 groups; less in gabapentin group as compared with placebo group (P=0.01 and 0.04, at rest and movement, respectively). A single oral dose of gabapentin 800 mg, as preemptive analgesic in patients undergoing surgery for brachial plexus injury is found to be an effective adjunct to intraoperative and postoperative pain. Pain is reduced not only at rest but also during movement.

Lamotrigine therapy in elderly patients with epilepsy, bipolar disorder or dementia

INTRODUCTION

In spite of circumstances that precipitate high use of anticonvulsants in geriatric populations, there is a paucity of data on the use of antiepileptic drugs in elderly patients with psychiatric and neurological disorders.

METHODS

Reports of lamotrigine therapy in elderly patients with epilepsy, bipolar disorder (BD), or dementia were identified by conducting an electronic search of major publication databases. Abstracts and presentations from professional meetings were searched as were the bibliographies of relevant articles.

RESULTS

Fourteen reports were identified, and included well-controlled prospective trials, retrospective analyses, and case reports of lamotrigine treatment. Controlled trials in elderly patients with epilepsy demonstrate efficacy and tolerability comparable to gabapentin. Improvement in bipolar depressive symptoms, improvement in core manic symptoms, and delay in mood relapse was reported in geriatric patients with BD. Preliminary case studies in patients with dementia note improvement in cognition and symptoms of agitation and depression.

CONCLUSION

Review of the available literature suggests lamotrigine is effective and well tolerated in elderly patients with epilepsy and relatively well-tolerated and may be effective in delaying mood relapse, particularly in the depressive pole, in patients with BD. While very limited literature suggests that lamotrigine may be effective and relatively well-tolerated in patients with dementia, further studies are needed.

Cost-effectiveness of add-on therapy with pregabalin in patients with refractory partial epilepsy

PURPOSE

To estimate the cost-effectiveness of pregabalin as add-on therapy in patients with refractory partial epilepsy.

METHODS

We developed a model to estimate clinical and economic outcomes over 1 year in a hypothetical cohort of patients with refractory partial epilepsy assumed alternatively to receive add-on therapy with pregabalin (300 mg/day) or no add-on therapy. For each patient in the model, we estimated the occurrence of seizure and side effects, using techniques of stochastic simulation. We assigned health-state utilities to each day of follow-up based on whether or not seizure or side effects were predicted to occur. Patients could discontinue therapy due to lack of efficacy or side effects. Outcomes included expected numbers of days without seizure ("seizure-free [SF] days"), quality-adjusted life-years (QALYs), and costs of therapy. Cost-effectiveness was assessed alternatively in terms of incremental cost per SF day gained and incremental cost per QALY gained.

RESULTS

Add-on therapy with pregabalin was estimated to result in an average gain of 23.8 SF days over one year; the estimated additional cost of therapy was $678. Incremental cost (mean, 95% CI) per SF day gained was $28.45 ($27.25, $29.44); corresponding estimates of incremental cost per QALY gained were $52,893 ($49,249, $56,983).

CONCLUSIONS

In patients with refractory partial epilepsy, the cost-effectiveness of pregabalin 300 mg/day compares favorably with published estimates of cost-effectiveness for other add-on antiepileptic drugs.

Gabapentin for the treatment of neuropathic pain in a pregnant horse

CASE DESCRIPTION

A 24-year-old 732-kg (1,610-lb) pregnant Belgian draft horse mare developed neuropathy and signs of intractable pain following colic surgery.

CLINICAL FINDINGS

Following recovery from colic surgery to treat compression of the small and large intestines because of a large fetus, the mare was noticed to have signs of femoral neuropathy involving the left hind limb. Within 36 hours after recovery, the mare developed signs of severe pain that were unresponsive to conventional treatment. No gastrointestinal tract or muscular abnormalities were found, and the discomfort was attributed to neuropathic pain.

TREATMENT AND OUTCOME

The mare was treated with gabapentin (2.5 mg/kg [1.1 mg/lb], PO, q 12 h). Shortly after this treatment was initiated, the mare appeared comfortable and no longer had signs of pain. Treatment was continued for 6 days, during which the dosage was progressively decreased, and the mare was discharged. The mare subsequently delivered a healthy foal.

CLINICAL RELEVANCE

Gabapentin appeared to be a safe, effective, and economical treatment for neuropathic pain in this horse.

Effect of a second-generation alpha2delta ligand (pregabalin) on visceral sensation in hypersensitive patients with irritable bowel syndrome

BACKGROUND

Visceral hypersensitivity is an important pathophysiological factor in irritable bowel syndrome (IBS). Pre-clinical studies suggest that the alpha(2)delta ligand pregabalin reduces both visceral allodynia and hyperalgesia, but is inactive on basal sensitivity.

AIM

To assess the effect of pregabalin on the perception of rectal distension in hypersensitive IBS patients.

METHODS

Twenty-six patients with Rome-II-defined IBS (aged 18-46 years, 7 male) were included in a randomized, double-blind, placebo-controlled, parallel-group study in which they received either 3 weeks oral pregabalin (titrated: 50 mg tid days 1-3, 100 mg tid days 4-7, 150 mg tid days 8-11; fixed 200 mg tid days 12-21 +/-4) or placebo control. Rectal sensitivity was assessed using a barostat technique, in which sensory thresholds were determined using the ascending method of limits, followed by tracking both before and after treatment. Only patients with a pain threshold of

RESULTS

Pregabalin significantly increased the sensory thresholds from baseline for first sensation (p = 0.045), desire to defecate (p = 0.008) and pain (p = 0.048) compared with placebo control. In addition, pregabalin significantly increased rectal compliance (p<0.0001), although this appeared to be unrelated to the changes in sensitivity. Despite the occurrence of mild dizziness and somnolence, pregabalin was generally well tolerated.

CONCLUSIONS

Pregabalin increased distension sensory thresholds to normal levels in IBS patients with rectal hypersensitivity. A concomitant increase in rectal compliance appeared to be unrelated to the reduction in sensitivity. These data suggest that alpha(2)delta ligands are worthy of further investigation in the treatment of visceral pain disorders, including IBS.

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Key Words

• pregabalin
• α2δ ligands
• visceral sensitivity
• irritable bowel syndrome

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MESH Headings

• Administration, Oral
• Adolescent
• Adult
• Analgesics/administration & dosage
• Analgesics/adverse effects
• Analgesics/blood
• Double-Blind Method
• Female
• Humans
• Irritable Bowel Syndrome/physiopathology
• Male
• Middle Aged
• Pain/physiopathology
• Pain Measurement
• Pain Threshold/physiology
• Pregabalin
• Pressure
• Rectum/physiopathology
• Sensation/physiology
• Sensory Thresholds/physiology
• gamma-Aminobutyric Acid/administration & dosage
• gamma-Aminobutyric Acid/adverse effects
• gamma-Aminobutyric Acid/analogs & derivatives
• gamma-Aminobutyric Acid/blood

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Safety Profile of Treatment in Diabetic Peripheral Neuropathic Pain: Table 1

New treatment options for diabetic peripheral neuropathic pain (DPNP) have recently been developed, including two Food and Drug Administration (FDA) approved agents, duloxetine and pregabalin. As clinicians face a broader spectrum of efficacious treatments, side-effect profiles play an increasingly important role in the development of a pain management regimen. In this article we review the safety profile of agents commonly used in the treatment of DPNP.

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.

Pregabalin for the treatment of generalized anxiety disorder: a novel pharmacologic intervention

Pregabalin is the first anxiolytic pharmacologic alternative for the treatment of generalized anxiety disorder (GAD) to be introduced in more than 10 years. GAD is a significant psychiatric condition with lifetime prevalence rates ranging between 5.7 and 6.4%. It causes significant impairment in quality of life and functional abilities equivalent to those associated with major depression. Randomized, controlled trials confirm that pregabalin is superior to placebo and comparable with lorazepam, alprazolam and venlafaxine for the treatment of patients with moderate-to-severe GAD. The onset of anxiolytic activity for pregabalin is apparent within 1 week following initiation of treatment, which is more rapid than that obtained with paroxetine and venlafaxine. Additionally, pregabalin has demonstrated potential for the prevention of relapse of GAD. Recently, the efficacy, safety and tolerability of pregabalin were also shown in a placebo-controlled study with elderly patients. Safety and tolerability profiles are favorable, with transient dizziness and somnolence of mild-to-moderate severity being the most commonly reported adverse events. Pregabalin has minimal potential for drug-drug interactions and does not provoke a clinically significant withdrawal response. Furthermore, pregabalin has low potential for abuse and dependence, unlike other classes of medications used for the treatment of GAD. Clinicians may consider the use of pregabalin in lieu of benzodiazepines as an alternative therapy for their patients with GAD.

Pregabalin for relief of neuropathic pain associated with diabetic neuropathy: a randomized, double-blind study

Seven published, randomized, placebo-controlled clinical trials with pregabalin have shown robust efficacy for relief of neuropathic pain from DPN and PHN. An investigation of the efficacy and safety of twice daily pregabalin enrolled 395 adults with painful DPN for > or = 1 year in a 12-week, double-blind, placebo-controlled trial. Patients were randomized to placebo, 150, 300, or 600 mg/day pregabalin (n = 96, 99, 99, and 101). Primary efficacy measure was change from baseline in endpoint mean pain score from patients' daily pain diaries. Secondary efficacy measures included pain-related sleep-interference scores, Patient and Clinical Global Impressions of Change (PGIC, CGIC), and the EuroQOL Health Utilities Index (EQ-5D). Statistically significant reduction in pain was observed in patients receiving pregabalin 600 mg/day, and 46% of patients treated with 600 mg/day pregabalin reported > or = 50% improvement in mean pain scores from baseline (vs 30% of placebo patients, p = 0.036). Number needed to treat to achieve such response was 6.3. Pregabalin 600 mg/day was significantly superior to placebo in improving pain-related sleep-interference scores (p = 0.003), PGIC (p = 0.021), and CGIC (p = 0.009). (Neither pregabalin 150 nor 300 mg/day separated from placebo on these measures, largely because of an atypically large placebo response in one country representing 42% of patients.) All pregabalin dosages were superior to placebo in improving EQ-5D utility scores (all p > or = 0.0263 vs placebo). Pregabalin was well tolerated at all dosages; adverse events were generally mild to moderate. Number needed to harm (discontinuation because of adverse events) was 10.3 for pregabalin 600 mg/day.

[Pregabalin in the treatment of neuropathic pain]

Pregabalin is increasingly being used for the treatment ofneuropathic pain, often as the first-line choice. The question is, however, whether this choice is based on evidence. Seven trials have been published on the effect ofpregabalin in patients with postherpetic neuralgia and painful diabetic neuropathy. These trials more frequently report a 50% reduction in pain in pregabalin treated patients than in patients treated with placebo (number needed to treat 4.3). Dizziness and somnolence are the most frequent adverse events of pregabalin. The number needed to harm for adverse events leading to discontinuation of treatment varies from 3.7 to 113.1 in these studies. Pregabalin has not been compared head-to-head with other drugs commonly used for neuropathic pain. Indirect comparison reveals the effectiveness of pregabalin is comparable with that of carbamazepin, tramadol, and gabapentin; pregabalin is possibly less effective than amitriptylin. However, taking into account its price and the lack of clinical experience and evidence, using pregabalin as first-line choice is not recommended.