Efficacy and Safety of Mecobalamin on Peripheral Neuropathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: To assess the efficacy and safety of mecobalamin on peripheral neuropathy. Background: Mecobalamin is an active form of vitamin B12 that has been suggested to be beneficial in improving nerve conduction and neuropathic pain symptoms. Although it is already widely used in Asia for the treatment of peripheral neuropathies, its efficacy remains unclear. Methods: Relevant electronic databases were systematically searched for randomized controlled trials investigating the efficacy and safety of mecobalamin on peripheral neuropathy, from inception through December 2019. Study selection, data extraction, and quality assessment were performed independently by two reviewers. The clinical therapeutic efficacy, pain score, neuropathic symptom score, nerve conduction velocities (NCVs), and adverse events of mecobalamin were assessed and were pooled by using a random-effects model. Heterogeneity was assessed by I² and chi-squared tests. Results: Fifteen studies with 1707 peripheral neuropathy patients caused by diabetic peripheral neuropathy and herpetic neuropathy were included. Based on Cochrane's risk of bias criteria, most of the included studies (11/15, 73%) were rated high risk of bias, whereas 20% and 7% were rated some concerns and low risk of bias, respectively. In terms of the proportion of patients achieving clinical therapeutic efficacy, mecobalamin alone (risk ratio [RR] = 1.17; 95% confidence interval [CI] 1.03-1.33) and mecobalamin in combination (RR = 1.32; 95% CI 1.21-1.45) are more effective than active control. For NCV outcomes, only mecobalamin combination treatment was effective. Neither mecobalamin alone nor mecobalamin in combination is effective on the pain score and neuropathic symptom outcomes. No serious adverse events associated with mecobalamin were reported during the treatment periods. Conclusion: Our findings indicate that mecobalamin in combination may be effective in improving clinical therapeutic efficacy and NCV outcomes for peripheral neuropathy patients, but the evidence is not clear for mecobalamin alone. More high-quality studies are required to confirm this finding.