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Acetyl-L-Carnitine for the Treatment of Peripheral Neuropathic Pain: a Systematic Review and Meta-Analysis

      Objectives

      Acetyl-L-carnitine (ALC), as a constructive component in fatty acid metabolism, is considered a potential agent for peripheral neuropathic pain (PNP). We aimed to access the efficacy and safety of ALC for the treatment of patients with PNP.

      Methods

      We searched PubMed up to March 2014 for randomized controlled trials (RCTs) comparing ALC with placebo or other active medications in diabetic and non-diabetic PNP patients. Two reviewers independently screened for eligible studies, assessed risk of bias, and extracted data. Mean difference (MD) and 95% confidence interval (CI) were used for pooling continuous data.

      Results

      Four RCTs compared ALC with placebo and reported in 3 articles (n = 523) were included. Compared with placebo, ALC significantly reduced Visual Analogue Scale (VAS) of PNP patients (MD, 1.28; 95%CI, 0.93-1.64, P < 0.00001). In the subgroup analysis, the efficacy of ALC on VAS was similar in different administration route (intramuscular-oral sequential subgroup: MD, 1.19; 95% CI, 0.34-2.04, P = 0.006; oral only subgroup: pooled MD, 1.15; 95% CI, 0.33-1.96, P = 0.006), and ALC appeared more effective in diabetic PNP patients than non-diabetic PNP patients (diabetic subgroup: MD, 1.47; 95% CI, 1.06-1.87, P < 0.00001; non-diabetic subgroup: MD, 0.71; 95% CI, -0.01-1.43, P = 0.05). No severe adverse events related to ALC were reported. The common adverse events were pain, headache, paraesthesia, hyperesthesia, retching, biliary colic and gastrointestinal disorders. The rates of total adverse events were similar in ALC and control group.

      Conclusions

      ALC could reduce VAS in PNP patients with acceptable safety. However, further trials with larger population and longer follow-up are required to confirm these findings.