Effectiveness of gabapentin in the treatment of chronic post-thoracotomy pain

BACKGROUND

Chronic post-thoracotomy pain (CPTP) consists of different types of pain. Some characteristics of CPTP are the same as those of recognized neuropathic pain syndromes.

OBJECTIVE

We aimed to determine the safety and efficacy of gabapentin (GP) in comparison to naproxen sodium (NS) in patients with CPTP.

METHODS

Forty consecutive patients with CPTP after posterolateral/lateral thoracotomy were prospectively evaluated. Twenty patients were given GP and another 20 were given NS treatment. Visual Analogue Scale (VAS) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scorings were performed pretreatment (day 0) and on the 15th, 30th, 45th and 60th days. Adverse events were questioned. The mean ages were 45.7+/-14.9 and 49.8+/-15.2 years and the mean durations of pain were 3.8+/-0.9 and 3.8+/-1.1 months, respectively.

RESULTS

The mean pretreatment VAS scores (VAS0) were 6.4+/-0.6 and 6.8+/-0.6, the mean pretreatment LANSS scores (LANSS0) were 18.85+/-1.6 and 20.75+/-2.6 in GP and NS groups, respectively (p>0.05). Minor adverse events which did not mandate discontinuation of treatment were observed in seven patients (35%) in the GP and in four patients (20%) in the NS group. The number of patients with a VAS score <5 at the latest follow-up (VAS60 < 5) was 17 (85%) and 3 (15%) in GP and NS groups, respectively (p<0.001). Seventeen patients (85%) in the GP and 0 patients (0%) in the NS group had a LANSS score <12 at the latest follow-up.

CONCLUSION

Gabapentin is safe and effective in the treatment of CPTP with minimal side effects and a high patient compliance. These results should be supported with multidisciplinary studies with larger sample sizes and longer follow-ups.

Do Surgical Patients Benefit from Perioperative Gabapentin/Pregabalin? A Systematic Review of Efficacy and Safety

BACKGROUND

Gabapentin and pregabalin have antiallodynic and antihyperalgesic properties useful for treating neuropathic pain. These properties may also be beneficial in acute postoperative pain. In this study we evaluated randomized, controlled trials examining the analgesic efficacy, adverse effects, and clinical value of gabapentinoids in postoperative pain.

METHODS

A systematic search of Medline, PubMed, and Cochrane Central Register of Controlled Trials (CENTRAL) databases yielded 22 randomized, controlled trials on perioperative administration of gabapentinoids for postoperative pain relief.

RESULTS

Pain relief was better in the gabapentin groups compared with the control groups. The opioid-sparing effect during the first 24 h after a single dose of gabapentin 300-1200 mg, administered 1-2 h preoperatively, ranged from 20% to 62%. The combined effect of a single dose of gabapentin was a reduction of opioid consumption equivalent to 30 +/- 4 mg of morphine (mean +/- 95% CI) during the first 24 h after surgery. Metaregression analysis suggested that the gabapentin-induced reduction in the 24-h opioid consumption was not significantly dependent on the gabapentin dose. Gabapentin reduced opioid-related adverse effects, such as nausea, vomiting, and urinary retention (number-needed-to-treat 25, 6, and 7, respectively). The most common adverse effects of the gabapentinoids were sedation and dizziness (number-needed-to-harm 35 and 12, respectively).

CONCLUSIONS

Gabapentinoids effectively reduce postoperative pain, opioid consumption, and opioid-related adverse effects after surgery. Conclusions about the optimal dose and duration of the treatment cannot be made because of the heterogeneity of the trials. Studies are needed to determine the long-term benefits, if any, of perioperative gabapentinoids.

Pregabalin: new indication. Generalised anxiety: better to use benzodiazepine

Seven placebo-controlled trials have shown that pregabalin has a modest effect on generalised anxiety in the short term. Pregabalin has not been shown to be as effective as a benzodiazepine or better tolerated.

[When the legs have to keep moving at night--the restless legs syndrome]

The restless legs syndrome (RLS) is a frequently occurring neurological disease that is often associated with sleep disorders and reduced quality of life. The cause of RLS still has not been clearly established; however, the dopaminergic and opioid systems and iron metabolism appear to have major roles in the disease. The therapy of choice is treatment with dopaminergic drugs. In addition, opiates and anticonvulsants such as gabapentin are used. The most important side effect of dopaminergic therapy is augmentation. If therapy-related augmentation occurs while taking levodopa, the medication should be changed to dopamine agonists. If augmentation occurs while taking dopamine agonists, opiates or gabapentin should be taken instead.

Prolonged myotonia and dystonia after general anaesthesia in a patient taking gabapentin

This is the report of a 55-yr-old female who developed severe myotonia and dystonia after general anaesthesia. Before starting on gabapentin therapy for a neuropathic pain condition, she had undergone numerous uneventful general anaesthetics. Since receiving treatment with gabapentin, she has experienced severe movement disorders on emergence from each subsequent general anaesthetic. The events were unrelated to the choice of anaesthetic or anti-emetic. The most recent event that required a protracted stay in hospital after a day-case surgery is presented in detail, and the possible mechanisms to explain the interaction are discussed.

Pregabalin in restless legs syndrome with and without neuropathic pain

BACKGROUND

Restless legs syndrome (RLS) is a common neurological disorder complicated in many patients by augmentation to dopaminergic therapy or comorbidities such as neuropathic pain.

AIMS

To explore the effectiveness of pregabalin in RLS in a pragmatic clinical setting.

METHODS

After observing improvement of restless legs symptoms in seven patients treated with pregabalin for neuropathic pain, we extended the clinical observation to a total of 16 patients with secondary RLS, in most of them due to neuropathy, and to three patients with idiopathic RLS.

RESULTS

Three patients discontinued pregabalin because of side effects (rash, fatigue, loss of efficacy). The other 16 patients self-rated a satisfactory or good alleviation of RLS symptoms and maintained pregabalin, five with add-on medication, on a mean daily dose of 305 mg (standard deviation, 185 mg), and with a mean duration of 217 (standard deviation, 183) days.

CONCLUSION

These data propose pregabalin as a new option in the treatment of secondary RLS for patients with neuropathic pain, which should be further investigated with randomized, placebo-controlled trials.

Safety and efficacy of anticonvulsants in elderly patients with psychiatric disorders: oxcarbazepine, topiramate and gabapentin

Few controlled studies are available to guide the clinician in treating potentially assaultive elderly individuals with psychiatric disorders. Safety concerns limit the use of benzodiazepines and antipsychotic medications in the elderly individual, making anticonvulsants an attractive alternative. This paper reviews three specific anticonvulsants for this purpose: gabapentin, oxcarbazepine and topiramate, describing safety and efficacy in elderly patients with severe agitation from psychosis or dementia. Gabapentin, renally excreted, with a half-life of 6.5-10.5 h, may cause ataxia. Oxcarbazapine, hepatically reduced, may cause hyponatremia, and topiramate may cause significant cognitive impairment. Nonetheless, these are important medications to consider in the treatment of agitation.

Isobolographic analysis of interaction between drugs with nonparallel dose-response relationship curves: a practical application

The objective of this study was to characterize the anticonvulsant and acute adverse-effect potentials of topiramate (TPM) and gabapentin (GBP)-two second-generation antiepileptic drugs administered alone and in combination in the maximal electroshock (MES)-induced seizures and chimney test in mice. The anticonvulsant and acute adverse effects of the combination of TPM with GBP at the fixed ratio of 1:1 were determined using the type I isobolographic analysis for nonparallel dose-response relationship curves (DRRCs). To ascertain any pharmacokinetic contribution to the observed interaction between TPM and GBP, total brain concentrations of both drugs were determined. The isobolographic analysis of interaction for TPM and GBP, whose DRRCs were not parallel in both MES and chimney tests, was accompanied with a presentation of all required calculations allowing the determination of lower and upper lines of additivity. The isobolographic analysis revealed that TPM combined with GBP at the fixed-ratio combination of 1:1 interacted supraadditively (synergistically) in terms of suppression of MES-induced seizures, and simultaneously, the combination produced additive interaction with respect to motor coordination impairment (adverse effects) in the chimney test. The evaluation of pharmacokinetic characteristics of interaction for the combination of TPM with GBP revealed that neither TPM nor GBP affected their total brain concentrations in experimental animals, and thus, the observed interaction in the MES test was pharmacodynamic in nature. In conclusion, the combination of TPM with GBP, because of supraadditivity in the MES test and additivity in terms of motor coordination impairment in the chimney test as well as lack of pharmacokinetic interactions between drugs, fulfilled the criterion of a favorable combination, worthy of recommendation in further clinical practice.

Pregabalin Augmentation of Quetiapine Therapy in the Treatment of Fibromyalgia: An Open-Label, Prospective Trial

INTRODUCTION

Quetiapine has been shown to improve fibromyalgia symptoms, especially sleep disturbance, fatigue, morning stiffness, and mental well-being, but lacks an effect on pain. The purpose of this study was to evaluate if pregabalin, which has shown antialgic activity in fibromyalgia, added to quetiapine treatment additionally improved fibromyalgia symptomatology.

METHODS

This was an open-label, 12-week study. Pregabalin was administered to 19 female fibromyalgia patients at a starting dose of 75 mg/day subsequently adjusted in according to the drug's efficacy and tolerability. Outcome measures included the Fibromyalgia Impact Questionnaire (FIQ), the Pittsburgh Sleep Quality Index, the Beck Depression Inventory, the State and Trait Anxiety Inventory, and the SF-12 Health Survey.

RESULTS

Data analysis was done on the Intention-To-Treat sample which included 18 patients. Pregabalin significantly improved the pain and tiredness after awakening subscales of the FIQ as well as the physical component of the SF-12. Six patients withdrew from the study, 3 because of side effects.

CONCLUSIONS

Our results suggest that the use of pregabalin can be a useful augmentation strategy in fibromyalgia patients partially responding to quetiapine.

A Double-Blind Evaluation of Gabapentin on Alcohol Effects and Drinking in a Clinical Laboratory Paradigm

INTRODUCTION

There has been increasing interest in the use of anticonvulsant agents in the treatment of alcoholism. Anticonvulsant agents have mostly been evaluated as an alternative to benzodiazepines in the treatment of alcohol withdrawal. Among the advantages of using anticonvulsant agents in this capacity is their purported lack of interaction with alcohol (i.e., interactions that could increase psychomotor deficits, cognitive impairment, and increase intoxication). This is particularly important in the treatment of alcohol withdrawal and relapse prevention in outpatients. Unfortunately, these untoward clinical interactions between anticonvulsants and alcohol in alcoholic patients have not been thoroughly assessed. The current clinical laboratory study was conducted to evaluate the safety and tolerability of the anticonvulsant gabapentin in alcoholic subjects. In addition, the ability of gabapentin to reduce alcohol craving and consumption was evaluated.

METHODS

Thirty-five non-treatment-seeking alcoholic subjects were enrolled in a subacute human laboratory study and received double-blind treatment with up to 1,200 mg of gabapentin (n=18) or placebo (n=17) for 8 days. The safety and tolerability of gabapentin were monitored in the natural environment during the first 5 days of medication treatment and during a free-choice limited access consumption paradigm following an initial drink of alcohol in a bar-lab setting on Day 7.

RESULTS

There was no overall effect of gabapentin on drinking or craving; however, it was tolerated (e.g., mood and sedation) as well as placebo over 5 days of natural drinking. During the bar-lab drinking session, there were no differences in subjective high or intoxication between subjects treated with gabapentin or placebo.

DISCUSSION

This study provides initial evidence that the anticonvulsant gabapentin is safe if used in conjunction with alcohol consumption in alcoholic individuals. Further study is needed with this and other lab models to determine the utility and safety of gabapentin in the treatment of alcoholism.

Effects of oral pregabalin and aprepitant on pain and central sensitization in the electrical hyperalgesia model in human volunteers †

BACKGROUND

Central sensitization is an important mechanism of neuropathic pain; its human models could be useful for early detection of efficacy of novel treatments. The electrical hyperalgesia model invokes central sensitization by repetitive stimulation of the skin. To assess its predictive value, we have investigated pregabalin, a standard neuropathic pain treatment, and aprepitant, an NK(1) antagonist, as an example of a drug class active in animal models but not in neuropathic pain patients. Furthermore, we explored if combinations of either of these drugs with the COX-2 inhibitor parecoxib could improve its efficacy.

METHODS

This was a double-blind, two-period, placebo-controlled study using incomplete block design. Thirty-two healthy volunteers received either oral pregabalin (titrated to 300 mg) or aprepitant (titrated to 320 mg), or matching placebo over 6 days before testing. Sensitization was assessed over 3 h; at 2 h, subjects received either parecoxib (40 mg) or saline i.v.

RESULTS

Pregabalin significantly reduced the areas of punctate mechanical hyperalgesia and dynamic touch allodynia vs placebo (both P < 0.0001); no significant reduction in the area of hyperalgesia or allodynia vs placebo was observed with aprepitant. In the pregabalin + parecoxib treated group, the area of allodynia was significantly reduced (P < 0.0001) and the area of hyperalgesia insignificantly attenuated (P = 0.09) vs placebo + parecoxib; no efficacy improvement was observed with aprepitant + parecoxib.

CONCLUSIONS

The model can serve to predict analgesic efficacy in early human development and investigate the mechanism of action. The model could also be used to explore efficacy of analgesic combinations to provide a rationale for patient studies.

Pregabalin and duloxetine for the treatment of neuropathic pain disorders

Clinical studies investigating the use of pregabalin and duloxetine for the management of diabetic peripheral neuropathy and post-herpetic neuralgia are reviewed. The benefits and potential drawbacks associated with these agents are discussed.

Gabapentin for smoking cessation: A preliminary investigation of efficacy

Gabapentin affects the glutamate and gamma amino butyric acid (GABA) neurotransmitters through which it may facilitate smoking abstinence. To obtain preliminary estimates of efficacy of gabapentin for smoking cessation, we conducted a single-arm, open-label study of gabapentin, 1,800-mg/day administered in three equal divided doses for 8 weeks. A total of 50 adult smokers were enrolled. All participants received a brief behavioral intervention at each medication visit. A total of 37 participants completed all follow-up assessments. At end-of-treatment the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 28% (95% CI=16%-42%) and 24% (95% CI=13%-38%), respectively. At 6 months, the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 20% (95% CI=10%-34%) and 16% (95% CI=7%-29%), respectively. Among subjects who continued to smoke and completed the follow-up assessments, the reported number of cigarettes smoked per day (mean+/-standard deviation) was significantly less than at baseline: -10.0+/-8.2 (p<.001). Adverse effects were minor and well tolerated. Our results suggest that gabapentin may increase smoking abstinence. An adequately powered randomized clinical trial assessing different doses of this drug against a placebo would be the reasonable next step.

Pregabalin: A novel γ-aminobutyric acid analogue in the treatment of neuropathic pain, partial-onset seizures, and anxiety disorders

BACKGROUND

The US Food and Drug Administration (FDA) approved pregabalin in December 2004 for the treatment of neuropathic pain associated with diabetic peripheral neuropathy and postherpetic neuralgia. Pregabalin is the first drug approved in the United States and in Europe for both conditions. In June 2005, pregabalin was approved as an adjunctive treatment in adults with partial-onset seizures. The FDA currently is considering the approval of pregabalin as adjunctive therapy in adults with generalized anxiety disorder (GAD) or social anxiety disorder (SAD).

OBJECTIVES

The goals of this review were to summarize the pharmacology, pharmacokinetics, efficacy, and tolerability of pregabalin; review its approved uses in the management of neuropathic pain and refractory partial-onset seizures; and investigate its potential use in patients with GAD or SAD.

METHODS

Relevant English-language literature was identified through a search of MEDLINE (1993-June 2006) and International Pharmaceutical Abstracts (2000-June 2006). The search terms included pregabalin, Lyrica, S-(+)-3 isobutyl-gaba, PN, DPN, diabetic peripheral neuropathy, PHN, postherpetic neuralgia, partial seizures, epilepsy, generalized anxiety disorder, and CI-1008.

RESULTS

In 4 clinical trials in a total of 1068 patients with diabetic peripheral neuropathy, the patients receiving pregabalin 300 to 600 mg/d had significantly greater improvement in mean pain scores than placebo recipients (P < or = 0.01). Patients with postherpetic neuralgia receiving pregabalin 450 to 600 mg/d had significantly greater improvement in relief of pain and pain-related sleep interference than placebo recipients (P < or = 0.002). Patients with refractory partial-onset seizures who received pregabalin 150 to 600 mg/d (divided into 2 or 3 doses) concomitantly with antiepileptic drugs had significantly fewer seizures than placebo recipients (P < or = 0.001). In the 3 studies that evaluated the efficacy of pregabalin in patients with GAD or SAD, the patients receiving pregabalin 200 to 600 mg/d (divided into 2 or 3 daily doses) had a significantly greater reduction in mean pain scores on the Hamilton Anxiety Scale than placebo recipients (P < or = 0.01). Across all the reviewed clinical trials, the most commonly reported adverse effects (AEs) were those affecting the central nervous system, including somnolence (< or =50%), dizziness (< or =49%), and headache (< or =29%). AEs resulted in withdrawal from the study in < or =32% of patients.

CONCLUSIONS

Pregabalin appears to be an effective therapy in patients with diabetic peripheral neuropathy, postherpetic neuralgia, and adults with refractory partial-onset seizures. The available data suggest that pregabalin may be beneficial as an adjunctive therapy in adult patients with GAD or SAD.

Treatment with gabapentin of 11 dogs with refractory idiopathic epilepsy

Eleven dogs diagnosed with refractory idiopathic epilepsy were treated orally with gabapentin for a minimum of three months at an initial dose of 10 mg/kg every eight hours. They were all experiencing episodes of generalised tonic-clonic seizures and had been treated chronically with a combination of phenobarbital and potassium bromide at doses sufficient to reach acceptable therapeutic serum levels without causing significant side effects. In each dog, the number of seizures per week, the average duration of the seizures and the number of days on which seizures occurred were compared for the three months before and after they were treated with gabapentin. A minimum 50 per cent reduction in the number of seizures per week was interpreted as a positive response to gabapentin, and six of the dogs showed a positive response. After the addition of gabapentin, both the number of seizures per week (P= 0.005) and the number of days with any seizures in a one-week period (P=0.03) were significantly reduced. Mild side effects of ataxia and sedation were observed in five of the dogs, but they were not severe enough to warrant the treatment being discontinued during the trial.

A randomized study of the effects of gabapentin on postamputation pain

BACKGROUND

Pain after amputation is common but difficult to treat. Therefore, the authors examined whether postoperative treatment with gabapentin could reduce postamputation stump and phantom pain.

METHODS

Forty-six patients scheduled to undergo lower limb amputation were randomly assigned to receive oral gabapentin or placebo. Treatment was started on the first postoperative day and continued for 30 days. The daily dose of gabapentin or placebo was gradually increased to 2,400 mg/day. The intensity of stump and phantom pain was recorded every day on a numeric rating scale (0-10) during the 30-day treatment period. Five interviews were performed after 7, 14, and 30 days and after 3 and 6 months.

RESULTS

Results from 41 patients were included in the data analysis. The risk of phantom pain (gabapentin vs. placebo) was 55.0% versus 52.6% (risk difference, 2.4%; 95% confidence interval, -28.9 to 33.7%; P = 0.88; 30 days) and 58.8% versus 50.0% (risk difference, 8.8%; 95% confidence interval, -23.3 to 40.9%; P = 0.59; 6 months). The median intensity of phantom pain (gabapentin vs. placebo) was 1.5 (range, 0-9.0) versus 1.2 (range, 0-6.6) (P = 0.60; 30 days) and 1.0 (range, 0-6.0) versus 0.5 (range, 0-5.0) (P = 0.77; 6 months). The median intensity of stump pain was 0.85 (range, 0-8.2) versus 1.0 (range, 0-5.4) (P = 0.68; 30 days) and 0 (range, 0-8.0) versus 0 (range, 0-5.0) (P = 0.58; 6 months).

CONCLUSION

Gabapentin administered in the first 30 postoperative days after amputation does not reduce the incidence or intensity of postamputation pain.

Gabapentin and postoperative pain – a systematic review of randomized controlled trials

The objective of this systematic review was to evaluate the efficacy and tolerability of perioperative gabapentin administration for the control of acute postoperative pain. We searched Medline (1966-2006), the Cochrane Library (2006), Scopus, CINAHL and bibliographies from clinical trials and review articles. We included randomized controlled trials (RCTs) comparing gabapentin with inactive controls in surgical patients. Sixteen valid RCTs were included. Weighted mean difference (WMD) for postoperative pain intensity (0-100 mm visual analogue scale) was -16.55 mm at 6 h and -10.87 mm at 24 h for treatment with a single preoperative dose of gabapentin 1200 mg. Cumulative opioid consumption at 24 h was also significantly decreased with gabapentin (WMD, -27.90 mg). When gabapentin was administered at doses less than 1200 mg, pain intensity was also lower at 6 h (WMD, -22.43 mm) and 24 h (WMD, -13.18 mm). Cumulative 24 h opioid consumption was also lower (WMD, -7.25 mg). Gabapentin was associated with an increased risk of sedation (Peto OR 3.86; 95% CI 2.50-5.94) but less opioid-related side effects such as vomiting (Peto OR 0.58; 95% CI 0.39-0.86) and pruritus (Peto OR 0.27; 95% CI 0.10-0.74). In conclusion, gabapentin has an analgesic and opioid-sparing effect in acute postoperative pain management when used in conjunction with opioids.

Pregabalin in central neuropathic pain associated with spinal cord injury: A placebo-controlled trial

OBJECTIVE

To evaluate pregabalin in central neuropathic pain associated with spinal cord injury.

METHODS

A 12-week, multicenter study of patients randomized to either flexible-dose pregabalin 150 to 600 mg/day (n = 70) or placebo (n = 67), administered BID. Patients were allowed to remain on existing, stable pain therapy. The primary efficacy variable was the endpoint mean pain score, derived from patients' last 7 days daily pain diary entries. Key secondary endpoints included pain responder rates, the SF-MPQ, sleep interference, mood, and the patient global measure of change.

RESULTS

The mean baseline pain score was 6.54 in the pregabalin group and 6.73 in the placebo group. The mean endpoint pain score was lower in the pregabalin group (4.62) than the placebo group (6.27; p < 0.001), with efficacy observed as early as week 1 and maintained for the duration of the study. The average pregabalin dose after the 3-week stabilization phase was 460 mg/day. Pregabalin was significantly superior to placebo in endpoint assessments on the SF-MPQ. The > or =30% and > or =50% pain responder rates were higher with pregabalin than placebo (p < 0.05). Pregabalin was associated with improvements in disturbed sleep (p < 0.001) and anxiety (p < 0.05), and more patients reported global improvement at endpoint in the pregabalin group (p < 0.001). Mild or moderate, typically transient, somnolence and dizziness were the most common adverse events.

CONCLUSIONS

Pregabalin 150 to 600 mg/day was effective in relieving central neuropathic pain, improving sleep, anxiety, and overall patient status in patients with spinal cord injury.