Patients with neuropathic pain (NP) are challenging to manage and evidence-based clinical recommendations for pharmacologic management are needed. Systematic literature reviews, randomized clinical trials, and existing guidelines were evaluated at a consensus meeting. Medications were considered for recommendation if their efficacy was supported by at least one methodologically-sound, randomized clinical trial (RCT) demonstrating superiority to placebo or a relevant comparison treatment. Recommendations were based on the amount and consistency of evidence, degree of efficacy, safety, and clinical experience of the authors. Available RCTs typically evaluated chronic NP of moderate to severe intensity. Recommended first-line treatments include certain antidepressants (i.e., tricyclic antidepressants and dual reuptake inhibitors of both serotonin and norepinephrine), calcium channel alpha2-delta ligands (i.e., gabapentin and pregabalin), and topical lidocaine. Opioid analgesics and tramadol are recommended as generally second-line treatments that can be considered for first-line use in select clinical circumstances. Other medications that would generally be used as third-line treatments but that could also be used as second-line treatments in some circumstances include certain antiepileptic and antidepressant medications, mexiletine, N-methyl-D-aspartate receptor antagonists, and topical capsaicin. Medication selection should be individualized, considering side effects, potential beneficial or deleterious effects on comorbidities, and whether prompt onset of pain relief is necessary. To date, no medications have demonstrated efficacy in lumbosacral radiculopathy, which is probably the most common type of NP. Long-term studies, head-to-head comparisons between medications, studies involving combinations of medications, and RCTs examining treatment of central NP are lacking and should be a priority for future research.

/pdf/pharmacologic-management-of-neuropathic-pain-evidence-based-54vtpxvnfe.pdf

Pharmacologic management of neuropathic pain: evidence-based recommendations.

Background Overstimulation of the N-methyl-D-aspartate (NMDA) receptor by glutamate is implicated in neurodegenerative disorders. Accordingly, we investigated memantine, an NMDA antagonist, for the treatment of Alzheimer's disease. Methods Patients with moderate-to-severe Alzheimer's disease were randomly assigned to receive placebo or 20 mg of memantine daily for 28 weeks. The primary efficacy variables were the Clinician's Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus) and the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory modified for severe dementia (ADCS-ADLsev). The secondary efficacy end points included the Severe Impairment Battery and other measures of cognition, function, and behavior. Treatment differences between base line and the end point were assessed. Missing observations were imputed by using the most recent previous observation (the last observation carried forward). The results were also analyzed with only the observed values included,...

https://www.nejm.org/doi/pdf/10.1056/NEJMoa013128

Memantine in Moderate-to-Severe Alzheimer's Disease

4 CLINICAL PARTICULARS 4.1 Therapeutic Indications Trimetazidine is indicated in adults as add-on therapy for the symptomatic treatment of patients with stable angina pectoris who are inadequately controlled by or intolerant to first-line antianginal therapies. 4.2 Posology and method of administration Oral administration. Posology The dose is one tablet of 35mg of trimetazidine twice daily during meals. Special populations Renal impairment In patients with moderate renal impairment (creatinine clearance [30-60] ml/min) (see sections 4.4 and 5.2), the recommended dose is 1 tablet of 35mg in the morning during breakfast. Elderly Elderly patients may have increased trimetazidine exposure due to age-related decrease in renal function (see section 5.2). In patients with moderate renal impairment (creatinine clearance [30-60] ml/min), the recommended dose is 1 tablet of 35mg in the morning during breakfast. Dose titration in elderly patients should be exercised with caution (see section 4.4). Health Products Regulatory Authority

Summary of product characteristics

Background and objectives:  This second European Federation of Neurological Societies Task Force aimed at updating the existing evidence about the pharmacological treatment of neuropathic pain since 2005.

Methods:  Studies were identified using the Cochrane Database and Medline. Trials were classified according to the aetiological condition. All class I and II randomized controlled trials (RCTs) were assessed; lower class studies were considered only in conditions that had no top-level studies. Treatments administered using repeated or single administrations were considered, provided they are feasible in an outpatient setting.

Results:  Most large RCTs included patients with diabetic polyneuropathies and post-herpetic neuralgia, while an increasing number of smaller studies explored other conditions. Drugs generally have similar efficacy in various conditions, except in trigeminal neuralgia, chronic radiculopathy and HIV neuropathy, with level A evidence in support of tricyclic antidepressants (TCA), pregabalin, gabapentin, tramadol and opioids (in various conditions), duloxetine, venlafaxine, topical lidocaine and capsaicin patches (in restricted conditions). Combination therapy appears useful for TCA-gabapentin and gabapentin-opioids (level A).

Conclusions:  There are still too few large-scale comparative studies. For future trials, we recommend to assess comorbidities, quality of life, symptoms and signs with standardized tools and attempt to better define responder profiles to specific drug treatments.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1468-1331.2010.02999.x

EFNS guidelines on the pharmacological treatment of neuropathic pain: 2010 revision

Background and objectives: This second European Federation of Neurological Societies Task Force aimed at updating the existing evidence about the pharmacological treatment of neuropathic pain since 2005. Methods: Studies were identified using the Cochrane Database and Medline. Trials were classified according to the aetiological condition. All class I and II randomized controlled trials (RCTs) were assessed; lower class studies were considered only in conditions that had no top-level studies. Treatments administered using repeated or single administrations were considered, provided they are feasible in an outpatient setting. Results: Most large RCTs included patients with diabetic polyneuropathies and postherpetic neuralgia, while an increasing number of smaller studies explored other conditions. Drugs generally have similar e!cacy in various conditions, except in trigeminal neuralgia, chronic radiculopathy and HIV neuropathy, with level A evidence in support of tricyclic antidepressants (TCA), pregabalin, gabapentin, tramadol and opioids (in various conditions), duloxetine, venlafaxine, topical lidocaine and capsaicin patches (in restricted conditions). Combination therapy appears useful for TCAgabapentin and gabapentin-opioids (level A). Conclusions: There are still too few large-scale comparative studies. For future trials, we recommend to assess comorbidities, quality of life, symptoms and signs with standardized tools and attempt to better define responder profiles to specific drug treatments.

EFNS guidelines on the pharmacological treatment of neuropathic pain: 2009 revision

Objective: To investigate the efficacy and safety of donepezil in patients with moderate to severe AD (standardized Mini-Mental State Examination [sMMSE] scores of 5 to 17; Functional Assessment Staging score ≤6 at baseline). Methods: Two-hundred ninety patients were randomized to treatment in this 24-week, double-blind, placebo-controlled trial. Patients received either donepezil 5 mg/day for the first 28 days and 10 mg/day thereafter as per the clinician’s judgment (n = 144) or placebo (n = 146). The primary outcome measure was the Clinician’s Interview-Based Impression of Change with caregiver input (CIBIC+). Results: Patients’ mean age was 73.6 years (range 48 to 92 years). Baseline demographics were similar between the treatment groups. Least squares (LS) mean ± SE sMMSE scores at baseline were 11.7 ± 0.35 for the donepezil group and 12.0 ± 0.34 for the placebo group. Patients receiving donepezil showed benefits on the CIBIC+, compared with placebo, at all visits up to week 24 ( p p Conclusion: These data suggest that donepezil’s benefits extend into more advanced stages of AD than those previously investigated, with very good tolerability.

A 24-week, randomized, double-blind study of donepezil in moderate to severe Alzheimer's disease.

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.

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

Objective: Pregabalin is effective in several neuropathic pain syndromes. This trial evaluated its efficacy, safety, and tolerability for treatment of painful HIV-associated neuropathy. Methods: This randomized, double-blind, placebo-controlled, parallel-group trial included a 2-week double-blind dose-adjustment (150–600 mg/day BID) phase, a 12-week double-blind maintenance phase, and an optional 3-month open label extension phase. The primary efficacy measure was the mean Numeric Pain Rating Scale (NPRS) score, an 11-point numeric rating scale. Secondary measures included Patient Global Impression of Change (PGIC) and sleep measurements. Results: Baseline mean NPRS score was 6.93 for patients randomized to pregabalin (n = 151) and 6.72 for those to placebo (n = 151). Pregabalin average daily dosage (SD) was 385.7 (160.3) mg/d. At endpoint, pregabalin and placebo showed substantial reductions in mean NPRS score from baseline: −2.88 vs −2.63, p = 0.3941. Pregabalin had greater improvements in NPRS score relative to placebo at weeks 1 (−1.14 vs −0.69, p = 0.0131) and 2 (−1.92 vs −1.43, p = 0.0393), and at weeks 7 (−3.22 vs −2.53 p = 0.0307) and 8 (−3.33 vs −2.53, p = 0.0156). At all other time points, differences between groups were not significant. Sleep measurements and 7-item PGIC did not differ among treatment groups; however, collapsed PGIC scores showed 82.8% of pregabalin and 66.7% of placebo patients rated themselves in 1 of the 3 “improved” categories ( p = 0.0077). Somnolence and dizziness were the most common adverse events with pregabalin. Conclusions: Pregabalin was well-tolerated, but not superior to placebo in the treatment of painful HIV neuropathy. Factors predicting analgesic response in HIV neuropathy warrant additional research. Classification of Evidence: This Class II trial showed that pregabalin is not more effective than placebo in treatment of painful HIV neuropathy.

/pdf/pregabalin-for-painful-hiv-neuropathy-a-randomized-double-iwl5vbs3pi.pdf

Pregabalin for painful HIV neuropathy: a randomized, double-blind, placebo-controlled trial.

Objective: To assess the efficacy and tolerability of pregabalin for the treatment of central neuropathic pain after spinal cord injury (SCI). Methods: Patients with chronic, below-level, neuropathic pain due to SCI were randomized to receive 150 to 600 mg/d pregabalin (n = 108) or matching placebo (n = 112) for 17 weeks. Pain was classified in relation to the neurologic level of injury, defined as the most caudal spinal cord segment with normal sensory and motor function, as above, at, or below level. The primary outcome measure was duration-adjusted average change in pain. Key secondary outcome measures included the change in mean pain score from baseline to end point, the percentage of patients with ≥30% reduction in mean pain score at end point, Patient Global Impression of Change scores at end point, and the change in mean pain-related sleep interference score from baseline to end point. Additional outcome measures included the Medical Outcomes Study–Sleep Scale and the Hospital Anxiety and Depression Scale. Results: Pregabalin treatment resulted in statistically significant improvements over placebo for all primary and key secondary outcome measures. Significant pain improvement was evident as early as week 1 and was sustained throughout the treatment period. Adverse events were consistent with the known safety profile of pregabalin and were mostly mild to moderate in severity. Somnolence and dizziness were most frequently reported. Conclusions: This study demonstrates that pregabalin is effective and well tolerated in patients with neuropathic pain due to SCI. Classification of evidence: This study provides Class I evidence that pregabalin, 150 to 600 mg/d, is effective in reducing duration-adjusted average change in pain compared with baseline in patients with SCI over a 16-week period ( p = 0.003, 95% confidence interval = −0.98, −0.20).

/pdf/a-randomized-trial-of-pregabalin-in-patients-with-4s18cunf6e.pdf

Ed Whalen

Papers

A 24-week, randomized, double-blind study of donepezil in moderate to severe Alzheimer's disease.

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 for painful HIV neuropathy: a randomized, double-blind, placebo-controlled trial.

A randomized trial of pregabalin in patients with neuropathic pain due to spinal cord injury

Pregabalin for Postherpetic Neuralgia: Placebo-Controlled Trial of Fixed and Flexible Dosing Regimens on Allodynia and Time to Onset of Pain Relief