Lacosamide in painful diabetic peripheral neuropathy: a phase 2 double-blind placebo-controlled study

BACKGROUND: Peripheral diabetic neuropathy affects between 20% and 45% of patients with diabetes. OBJECTIVE: To ascertain the effect of lacosamide on pain associated with peripheral diabetic neuropathy. METHODS: One hundred nineteen patients with a 1 to 5-year history of pain attributed to diabetic neuropathy and a score of > or =4 on the Likert pain scale entered the multicenter, randomized, double-blind, placebo-controlled trial. Lacosamide (N=60) titrated from 100 to 400 mg/d or maximum tolerated dose and placebo (N=59) were the trial interventions. Primary efficacy criterion was change in pain score on the 11-point Likert pain scale. Secondary assessments included Short-Form McGill Pain and Short-Form-36 Quality of Life Questionnaires, sleep/activity interference, pain intensity, Patient and Clinical Global Impression of Change, and Profile of Mood. Patients receiving at least 1 dose of medication underwent safety evaluation. RESULTS: Ninety-four patients (lacosamide 46; placebo 48) completed the trial. Lacosamide had significantly (P=0.039) better pain relief versus placebo (primary outcome). Improvements were also seen in secondary outcome measures. Adverse events occurred in 52 lacosamide and 44 placebo patients. Common adverse events, occurring in > or =5% of patients, were headache (lacosamide 18%, placebo 22%), dizziness (lacosamide 15%, placebo 8%), and nausea (lacosamide 12%, placebo 7%). Five lacosamide and 3 placebo patients withdrew for adverse events. DISCUSSION: Lacosamide seems to attenuate pain in diabetic neuropathy in doses up to 400 mg/d and improves quality of life issues.     

Efficacy and Safety of Lacosamide in Painful Diabetic Neuropathy

OBJECTIVE

To evaluate efficacy and safety of lacosamide compared with placebo in painful diabetic polyneuropathy.

RESEARCH DESIGN AND METHODS

Diabetic patients with at least moderate neuropathic pain were randomized to placebo or lacosamide 400 (in a slow or standard titration) or 600 mg/day over 6-week titration and 12-week maintenance periods. Primary efficacy criterion was intra-individual change in average daily Numeric Pain Rating Scale score from baseline to the last 4 weeks.

RESULTS

For the primary end point, pain reduction was numerically but not statistically greater with lacosamide compared with placebo (400 mg/day, P = 0.12; 600 mg/day, P = 0.18). Both doses were significantly more effective compared with placebo over the titration (P = 0.03, P = 0.006), maintenance (P = 0.01, P = 0.005), and entire treatment periods (P = 0.03, P = 0.02). Safety profiles between titration schemes were similar.

CONCLUSIONS

Lacosamide reduced neuropathic pain and was well tolerated in diabetic patients, but the primary efficacy criterion was not met, possibly due to an increased placebo response over the last 4 weeks.Up to one in four patients with diabetes may be affected by chronic diabetic painful neuropathy (DPN) (1,2) and suffer substantial morbidity and impaired quality of life (3). Because the current treatment options are limited, there is continued need for new therapeutic approaches (3,4). Lacosamide is an anticonvulsant with a unique mode of action, selectively enhancing slow inactivation of voltage-gated sodium channels (5–8). This trial was one of three similarly designed placebo-controlled, parallel-group trials to evaluate the efficacy of lacosamide in DPN (9,10) using 400 mg/day (two titration schemes) and 600 mg/day.     

Long‐term oral lacosamide in painful diabetic neuropathy: A two‐year open‐label extension trial

Objectives: This open‐label follow‐on trial aimed to investigate long‐term safety and efficacy of lacosamide in patients with painful diabetic neuropathy. Methods: After 1‐week baseline period, lacosamide 100mg/day was started. Each week, based on pain and safety assessments, doses were escalated by 100mg/day to an optimal level, up to a maximum of 400mg/day. Patients then entered the 20‐week maintenance period (dose adjusted as needed). Thereafter, patients could opt to continue lacosamide up to about 2.5 years (extension period). Results: Of the 69 enrolled patients, 47 (68%) completed the 20‐week maintenance period and elected to continue into the extension period; 37/69 (54%) patients were in the extension period for more than one year and 34/69 (49%) continued until study termination. The modal lacosamide dose in most patients (54%) was 400mg/day. Headache, upper respiratory tract infection, arthralgia, sinusitis, nasopharyngitis, and back pain were the most frequently reported adverse events (≥10% of patients). Significant reductions from baseline in Likert pain scores began during dose titration and were sustained throughout the study. Significant improvements were also seen in Neuropathic Pain Scale, Quality of Life scores, and Patient's Global Impression of Change assessment. Of 34 patients at study termination, 32 (90%) elected to continue with lacosamide treatment in another long‐term open‐label trial (NCT00235443). Conclusion: The long‐term safety profile and sustained efficacy of lacosamide observed in this trial support its continued development for treatment of painful diabetic neuropathy.     

Efficacy of pregabalin in neuropathic pain evaluated in a 12-week, randomised, double-blind, multicentre, placebo-controlled trial of flexible- and fixed-dose regimens

Pregabalin binds with high affinity to the alpha2-delta subunit protein of voltage-gated calcium channels and, thereby, reduces release of excitatory neurotransmitters. This 12-week randomised, double-blind, multicentre, placebo-controlled, parallel-group study evaluated the efficacy and safety of pregabalin in patients with chronic postherpetic neuralgia (PHN) or painful diabetic peripheral neuropathy (DPN). Patients were randomised to placebo (n=65) or to one of two pregabalin regimens: a flexible schedule of 150, 300, 450, and 600 mg/day with weekly dose escalation based on patients' individual responses and tolerability (n=141) or a fixed schedule of 300 mg/day for 1 week followed by 600 mg/day for 11 weeks (n=132). Both flexible- and fixed-dose pregabalin significantly reduced endpoint mean pain score (primary outcome) versus placebo (P=0.002, P<0.001) and were significantly superior to placebo in improving pain-related sleep interference (P<0.001). The most common adverse events (AEs) for pregabalin-treated patients were dizziness, peripheral oedema, weight gain (not affecting diabetes control), and somnolence. These results are consistent with previous studies' demonstrating pregabalin's efficacy, tolerability, and safety for treatment of chronic neuropathic pain associated with DPN or PHN. Pregabalin dosing aimed at optimal balance of efficacy and tolerability provides significant pain relief and may reduce risks for AEs and therapy discontinuation.     

Gabapentin dosing for neuropathic pain: evidence from randomized,placebo-controlled clinical trials

BACKGROUND: Pain is one of the most common reasons for seeking medical attention, and neuropathic pain is among the most common types of pain. Despite its prevalence, neuropathic pain is often underrecognized and inadequately treated. Many cases are refractory to the medications traditionally used for pain, such as nonsteroidal anti-inflammatory drugs. Tricyclic antidepressants are considered first-line agents for neuropathic pain, but their use is limited by unwanted side effects and a risk of cardiovascular mortality. OBJECTIVES: The goals of this article were to review data on the efficacy and tolerability of gabapentin in the treatment of neuropathic pain in adults and to determine the optimal dosing schedule. METHODS: Randomized controlled studies of gabapentin for neuropathic pain were identified through a search of PubMed and MEDLINE from 1966 to the present using the search terms gabapentin, randomized, placebo, and pain. Abstracts of identified articles were screened for study size (>100 patients per treatment arm) and use of appropriate efficacy measures. A separate review based on information provided by the manufacturer of gabapentinaand clinical trial Web sites was conducted to ascertain whether there had been any other relevant industry- or government-sponsored trials. The manufacturer provided additional unpublshed study data. RESULTS: Data from 5 randomized, placebo-controlled trials were included in the review, 1 of which has not yet been published. Gabapentin was effective in the treatment of painful diabetic neuropathy, postherpetic neuralgia, and other neuropathic pain syndromes. It relieved symptoms of allodynia, burning pain, shooting pain, and hyperesthesia. Adverse effects were typically mild to moderate and usually subsided within approximately 10 days from the initiation of treatment. Based on available data, it appears that treatment should be started at a dose of 900 mg/d (300 mg/d on day 1, 600 mg/d on day 2, and 900 mg/d on day 3). Additional titration to 1800 mg/d is recommended for greater efficacy. Doses up to 3600 mg/d may be needed in some patients. The effective dose should be individualized according to patient response and tolerability. CONCLUSION: At doses of 1800 to 3600 mg/d, gabapentin was effective and well tolerated in the treatment of adults with neuropathic pain.     

A Randomized,Controlled Trial of Oxycodone Versus Placebo in Patients With PostHerpetic Neuralgia and Painful Diabetic Neuropathy Treated With Pregabalin

The aim of this randomized double-blind, placebo-controlled, parallel-group study was to evaluate the efficacy, safety, and tolerability of pregabalin in combination with oxycodone or placebo, in patients with either postherpetic neuralgia (PHN) or painful diabetic neuropathy (PDN). After a 7-day washout period, 62 patients were randomized to receive either oxycodone mixture 10 mg/day or placebo mixture for 1 week. Patients were then started on open-label pregabalin (75, 150, 300 and 600 mg/day) according to a forced titration dosing regimen, while continuing the same dosage of oxycodone or placebo for 4 weeks. The primary efficacy measure was a decrease in the pain-intensity score of at least 2cm and a pain score <4cm measured using a 10-cm visual analogue scale (VAS) following pregabalin dosage escalation and treatment for 4 weeks. Secondary efficacy measures included sleep interference and the Neuropathic Pain Scale. There were similar levels of overall efficacy between pregabalin/oxycodone and pregabalin/placebo groups in relieving PHN and PDN related pain.PerspectivePeripheral neuropathic pain presents commonly in clinical practice, and 2 of its most prevalent types are PHN and PDN. Currently available treatments provide some degree of pain relief in ～40-60% of patients, leaving the remainder with unremitting pain. Although this study supports the effectiveness of pregabalin in the treatment of PHN or PDN, it also shows that the addition of a low dose of oxycodone at 10mg/day does not enhance the pain-relieving effects of pregabalin.     

Relief of painful diabetic peripheral neuropathy with pregabalin: a randomized, placebo-controlled trial.

This was a 6-week, randomized, double-blind, multicenter study evaluating the efficacy of pregabalin in the treatment of painful diabetic neuropathy. Two hundred forty-six men and women with painful diabetic neuropathy received pregabalin (150 or 600 mg/day by mouth) or placebo. The primary efficacy variable was mean pain score at the end of treatment. Efficacy results indicate that pregabalin 600 mg/day significantly decreased mean pain score to 4.3 (vs 5.6 for placebo, P = .0002) and increased the proportion of patients who had a > or =50% decrease from baseline pain (39% vs 15% for placebo, P = .002). Pregabalin also significantly reduced sleep interference, past week and present pain intensity, sensory and affective pain scores, and bodily pain and decreased by > or =50% the number of patients describing their pain as gnawing, sickening, fearful, and punishing-cruel. More patients receiving pregabalin 600 mg/day than placebo showed improvement, as rated on the Clinical and Patient Global Impression of Change scales, 73% vs 45% and 85% vs 47%, respectively. Pregabalin 150 mg/day was essentially no different from placebo. Dizziness was the most common side effect. These study results show pregabalin 600 mg/day to be safe and effective in reducing the pain and other associated symptoms of painful diabetic neuropathy. PERSPECTIVE: Painful diabetic peripheral neuropathy is a challenging neuropathic pain syndrome. This randomized controlled trial demonstrates that pregabalin, a new drug that interacts with the alpha2-delta protein subunit of the voltage-gated calcium channel, is an efficacious and safe treatment for the pain of this condition.     

Efficacy, safety, and tolerability of pregabalin treatment for painful diabetic peripheral neuropathy: findings from seven randomized, controlled trials across a range of doses

OBJECTIVE—To evaluate the efficacy, safety, and tolerability of pregabalin across the effective dosing range, to determine differences in the efficacy of three times daily (TID) versus twice daily (BID) dosage schedules, and to use time-to-event analysis to determine the time to onset of a sustained therapeutic effect using data from seven trials of pregabalin in painful diabetic peripheral neuropathy (DPN).RESEARCH DESIGN AND METHODS—Data were pooled across seven double-blind, randomized, placebo-controlled trials using pregabalin to treat painful DPN with dosages of 150, 300, and 600 mg/day administered TID or BID. Only one trial included all three of these dosages, and TID dosing was used in four. All studies shared fundamental selection criteria, and treatment durations ranged from 5 to 13 weeks.RESULTS—Pooled analysis showed that pregabalin significantly reduced pain and pain-related sleep interference associated with DPN (150, 300, and 600 mg/day administered TID vs. placebo, all P ≤ 0.007). Only the 600 mg/day dosage showed efficacy when administered BID (P ≤ 0.001). Pain and sleep interference reductions associated with pregabalin appear to be positively correlated with dosage; the greatest effect was observed in patients treated with 600 mg/day. Kaplan-Meier analysis revealed that the median time to onset of a sustained (≥30% at end point) 1-point improvement was 4 days in patients treated with pregabalin at 600 mg/day, 5 days in patients treated with pregabalin at 300 mg/day, 13 days in patients treated with pregabalin at 150 mg/day, and 60 days in patients receiving placebo. The most common treatment-emergent adverse events were dizziness, somnolence, and peripheral edema.CONCLUSIONS—Treatment with pregabalin across its effective dosing range is associated with significant, dose-related improvement in pain in patients with DPN.The prevalence of diabetic neuropathy is as high as 50% in patients who have had diabetes for 25 years (1), and painful diabetic peripheral neuropathy (DPN) occurs in up to 26% of all people with diabetes (2). Symptoms range from mild dysesthesias to severe unremitting pain that can profoundly impact patients’ lives (3,4).Medications of several different classes are used to treat painful DPN with varying degrees of efficacy, safety, and tolerability. The antiepileptic agents gabapentin and pregabalin have attained widespread use in the treatment of painful DPN. These agents bind to the auxiliary α2-δ subunit of the voltage-sensitive calcium channel, thereby decreasing Ca²⁺ influx at nerve terminals and modulating neurotransmitter release (5).There are seven double-blind, randomized, placebo-controlled trials in painful DPN with pregabalin (6–12), five of which are published in full (7–11). The effective dosing range for treatment of neuropathic pain syndromes is 150 to 600 mg/day, administered either three times daily (TID) or twice daily (BID). Among the seven trials, dosages of 150, 300, and 600 mg/day were used, but only one trial included all three of these dosages. Thus, individually, the seven trials present an incomplete picture of the effective dosing range. In addition, TID dosing was used in the first four trials, whereas the three most recent trials of pregabalin in painful DPN used BID dosing.The objective of the current report is to use the pooled data from these seven trials to evaluate the efficacy, safety, and tolerability of pregabalin across the effective dosing range. We also use these data to determine differences in the efficacy of TID and BID dosing schedules. Finally, we use a time-to-event analysis of the pooled data to determine the time to onset of a sustained therapeutic effect across the range of doses.     

Rationale and design of a randomized double-blind clinical trial in breast cancer: Dextromethorphan in chemotherapy-induced peripheral neuropathy

BackgroundAnti-cancer chemotherapy often induces peripheral neuropathy and consequent cognitive and quality of life impairment. Guidelines recommend antiepileptics or antidepressants but their efficacy is limited.Dextromethorphan, a N-methyl-D-aspartate receptor antagonist, has shown its efficacy in painful diabetic neuropathy and in post-operative pain but has not been studied in chemotherapy-induced peripheral neuropathy. This clinical trial evaluates the effect of dextromethorphan on pain, cognition and quality of life in patients who suffer from neuropathic pain induced by chemotherapy for breast cancer. It also assesses the impact of dextromethorphan genetic polymorphism on analgesia.Methods and designThis trial is a randomized, placebo-controlled, double-blind clinical study in two parallel groups (NCT02271893). It includes 40 breast cancer patients suffering from chemotherapy-induced peripheral neuropathy. They are randomly allocated to dextromethorphan (maximal dose 90 mg/day) or placebo for 4 weeks. The primary endpoint is pain intensity measured after 4 weeks of treatment on a (0–10) Numeric Pain Rating Scale. Secondary outcomes include assessment of neuropathic pain, cognitive function, anxiety/depression, sleep and quality of life. Data analysis is performed using mixed models and the tests are two-sided, with a type I error set at α = 0.05.DiscussionConsidering the poor efficacy of available drugs in chemotherapy-induced neuropathic pain, dextromethorphan may be a valuable therapeutic option. Pharmacogenetics may provide predictive factors of dextromethorphan response in patients suffering from breast cancer.     

Randomized control trial of topical clonidine for treatment of painful diabetic neuropathy

A length-dependent neuropathy with pain in the feet is a common complication of diabetes (painful diabetic neuropathy). It was hypothesized that pain may arise from sensitized-hyperactive cutaneous nociceptors, and that this abnormal signaling may be reduced by topical administration of the α₂-adrenergic agonist, clonidine, to the painful area. This was a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial. Nociceptor function was measured by determining the painfulness of 0.1% topical capsaicin applied to the pretibial area of each subject for 30 minutes during screening. Subjects were then randomized to receive 0.1% topical clonidine gel (n = 89) or placebo gel (n = 90) applied 3 times a day to their feet for 12 weeks. The difference in foot pain at week 12 in relation to baseline, rated on a 0–10 numerical pain rating scale (NPRS), was compared between groups. Baseline NPRS was imputed for missing data for subjects who terminated the study early. The subjects treated with clonidine showed a trend toward decreased foot pain compared to the placebo-treated group (the primary endpoint; P = 0.07). In subjects who felt any level of pain to capsaicin, clonidine was superior to placebo (P < 0.05). In subjects with a capsaicin pain rating ?2 (0–10, NPRS), the mean decrease in foot pain was 2.6 for active compared to 1.4 for placebo (P = 0.01). Topical clonidine gel significantly reduces the level of foot pain in painful diabetic neuropathy subjects with functional (and possibly sensitized) nociceptors in the affected skin as revealed by testing with topical capsaicin. Screening for cutaneous nociceptor function may help distinguish candidates for topical therapy for neuropathic pain.     

Efficacy of oxcarbazepine in the treatment of painful diabetic neuropathy

OBJECTIVES: To evaluate the safety, tolerability, and efficacy of oxcarbazepine in the treatment of painful diabetic neuropathy. METHODS: This was an open-label, 9-week trial, consisting of a 1-week prospective Screening Phase followed by an 8-week Treatment Phase. Treatment with oxcarbazepine was initiated at 150 mg/day, and the daily dose was doubled on a weekly basis and titrated to tolerability over 4 weeks, up to 1200 mg/day. This was followed by a 4-week fixed-dose Maintenance Phase, during which patients were maintained on oxcarbazepine at 1200 mg/day or highest tolerated dose. The primary efficacy variable was the change in the weekly pain rating assessed on the Visual Analog Scale (VAS) of the short-form McGill Pain Questionnaire between the Screening Phase and the Treatment Phase. All analyses were performed on the intent-to-treat population. RESULTS: Thirty patients were enrolled in the trial. The mean daily oxcarbazepine dose during the Maintenance Phase was 814 mg. The mean VAS score dropped from 66.3 during the Screening Phase to 34.3 at the end of the trial (P = 0.0001), for a mean reduction of 48.3%. In addition, there were significant improvements in the total pain score and present pain intensity. Oxcarbazepine was well tolerated, with the most common adverse events consisting of drowsiness and dizziness. DISCUSSION: The results suggest that oxcarbazepine administered as monotherapy is an efficacious and safe option for the symptomatic treatment of pain associated with symmetrical diabetic neuropathy. These results will need to be confirmed in large, double-blind, placebo-controlled, randomized clinical trials.     

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.     

Gabapentin vs. amitriptyline in painful diabetic neuropathy: an open-label pilot study

The objective of this study was to compare the efficacy and tolerability of gabapentin and amitriptyline monotherapy in painful diabetic neuropathy. This was a 12-week, open-label, prospective, randomized trial. Twenty-five type-II diabetic patients with pain attributed to diabetic neuropathy and a minimum score of 2 on a pain intensity scale ranging from 0 (no pain) to 4 (excruciating pain) were randomized to receive either gabapentin, titrated from 1,200 mg/day to a maximum of 2,400 mg/day, or amitriptyline, titrated from 30 mg/day to a maximum of 90 mg/day. Both drugs were titrated over a 4-week period and maintained at the maximum tolerated dose for 8 weeks. The main outcome measures were weekly pain intensity and paresthesia intensity, measured on two categorical scales. Thirteen patients received gabapentin and 12 received amitriptyline. All 25 patients completed the trial. Gabapentin produced greater pain reductions than amitriptyline (mean final scores were 1.9 vs. 1.3 points below baseline scores; P = 0.026). Decreases in paresthesia scores also were in favor of gabapentin (1.8 vs. 0.9 points; P = 0. 004). Adverse events were more frequent in the amitriptyline group than in the gabapentin group: they were reported by 11/12 (92%) and 4/13 (31%) of patients, respectively (P = 0.003). Side effects were the main limiting factor preventing dose escalation. Gabapentin produced greater improvements than amitriptyline in pain and paresthesia associated with diabetic neuropathy. Additionally, gabapentin was better tolerated than amitriptyline. Further controlled trials are needed to confirm these preliminary results.     

Lacosamide for the treatment of epilepsy

Lacosamide is a third-generation antiepilepsy drug approved for adjunctive treatment of partial-onset seizures in adults. The pharmacology of lacosamide includes linear kinetics, complete bioavailability, and no major drug interactions. Lacosamide produces slow inactivation of neuronal sodium channels, which differentiates it from other sodium channel modulators, such as carbamazepine and phenytoin. The drug was effective with no major safety problems detected in three large placebo-controlled pivotal trials and has been released in Europe and the US at 200–400 mg/day, divided b.i.d.; an intravenous formulation is approved for temporary conversion from oral therapy. This article reviews the clinical development, pharmacology, and uses of lacosamide for treating partial-onset seizures in adults.     

Efficacy of desipramine in painful diabetic neuropathy: a placebo-controlled trial

Although amitriptyline relieves pain in many patients with painful diabetic neuropathy, side effects often preclude effective treatment. Desipramine has the least anticholinergic and sedative effects of the first generation tricyclic antidepressants. We compared a 6 week course of desipramine (mean dose, 201 mg/day) to active placebo in 20 patients with painful diabetic neuropathy in a double-blind crossover trial. Pain relief with desipramine was statistically significant in weeks 5 and 6. Eleven patients reported at least moderate relief with desipramine, compared to 2 with placebo. Pain relief tended to be greater in depressed patients, but relief was also observed in patients who did not show an antidepressant effect. We conclude that desipramine relieves pain in many patients with painful diabetic neuropathy, offering an alternative for patients unable to tolerate amitriptyline. Blockade of norepinephrine reuptake, an action shared by desipramine, amitriptyline, and other antidepressants proven effective in neuropathic pain, may mediate this analgesic effect.     

Wirksamkeit und Wirkungsbeginn von Pregabalin bei Patienten mit neuropathischen Schmerzen

Background

The data from a previously published 12-week randomised, double-blind, placebo-controlled multicentre study on the efficacy and safety of pregabalin were analyzed for time to onset of analgesic action with neuropathic pain.

Patients and methods

A total of 338 patients with postherpetic neuralgia or painful diabetic peripheral neuropathy were treated with flexible or fixed regimens of pregabalin at daily doses of up to 600 mg/day (n=141 and 132, respectively) or placebo (n=65).

Results

Under fixed dose treatment, a decrease of one full point on the 11-point numerical rating pain scale was reached on day 1, two full points on day 13, and three full points on day 23 (under flexible dose pregabalin: on days 6, 17 and 30). In both treatment arms, pain reduction was statistically significant (P=0.001, P=0.002 vs placebo, respectively).

Conclusion

In patients with chronic neuropathic pain, the analgesic effect of both pregabalin treatment regimens was high and associated with a rapid time to onset.     

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.     

Effectiveness and time to onset of pregabalin in patients with neuropathic pain

BACKGROUND: The data from a previously published 12-week randomised, double-blind, placebo-controlled multicentre study on the efficacy and safety of pregabalin were analyzed for time to onset of analgesic action with neuropathic pain. PATIENTS AND METHODS: A total of 338 patients with postherpetic neuralgia or painful diabetic peripheral neuropathy were treated with flexible or fixed regimens of pregabalin at daily doses of up to 600 mg/day (n=141 and 132, respectively) or placebo (n=65). RESULTS: Under fixed dose treatment, a decrease of one full point on the 11-point numerical rating pain scale was reached on day 1, two full points on day 13, and three full points on day 23 (under flexible dose pregabalin: on days 6, 17 and 30). In both treatment arms, pain reduction was statistically significant (P=0.001, P=0.002 vs placebo, respectively). CONCLUSION: In patients with chronic neuropathic pain, the analgesic effect of both pregabalin treatment regimens was high and associated with a rapid time to onset.     

Lacosamide displays potent antinociceptive effects in animal models for inflammatory pain.

Lacosamide is a functionalized amino acid which was initially synthesized as an antiepileptic drug. In addition to its broad anti-seizure activity, lacosamide was shown to display efficacy in animal models for neuropathic pain and is currently in phase III clinical development for the treatment of epilepsy and neuropathic pain. In order to further profile its antinociceptive properties, the effects of lacosamide on inflammatory pain in the formalin test, the carrageenan model and the adjuvant-induced arthritis model were investigated. For the formalin test, mice received an intraplantar injection of formalin and the subsequent licking response was measured over 45 min. Lacosamide was administered 30 min before formalin. For the carrageenan model, mechanical and thermal hyperalgesia were assessed 3 h following an intraplantar injection of carrageenan. Lacosamide was administered to rats 30 min before pain threshold measurements. For the adjuvant-induced arthritis test rats received intraplantar injections of Freund's complete adjuvant into the right hindpaw which lead to the development of arthritic symptoms in all animals tested for antinociception. On day 11 after arthritis induction, mechanical hyperalgesia was assessed by the modified Randall Selitto paw pressure test following acute treatment with lacosamide. Lacosamide dose-dependently attenuated mechanical hyperalgesia following carrageenan injection and in rats suffering from Freund's complete adjuvant-induced arthritis. Moreover, thermal hyperalgesia induced by carrageenan as well as the formalin-induced licking response were dose-dependently attenuated by lacosamide. These results suggest lacosamide may be active against various forms of acute and chronic inflammatory pain in humans.     

Duloxetine,a centrally acting analgesic,in the treatment of patients with osteoarthritis knee pain: A 13-week,randomized, placebo-controlled trial

Pain is a common cause of disability in osteoarthritis. Duloxetine, a serotonin and norepinephrine reuptake inhibitor (SNRI), has demonstrated analgesic effects in diabetic peripheral neuropathy and fibromyalgia. Considering its central mechanism of action, duloxetine may be effective in other pain states with evidence of central sensitization. Herein, we report the results of a 13-week, randomized, double-blind, placebo-controlled trial of duloxetine (60–120 mg/day) versus placebo in the treatment of knee pain in 231 patients meeting clinical and radiographic criteria for osteoarthritis of the knee. Duloxetine was superior to placebo on the primary efficacy measure (weekly mean 24-h pain scores) beginning at Week 1 and continuing through the treatment period (P ? .05). There was also a significant improvement in the WOMAC physical functioning subscale and several other secondary outcomes. Adverse-event rates did not differ significantly between treatment groups (49.5% for duloxetine 60–120 mg/day, and 40.8% for placebo).