Acetyl-L-Carnitine in the Treatment of Peripheral Neuropathic Pain
Acetyl-L-Carnitine (ALC) has a moderate effect in reducing pain on peripheral neuropathic pain (PNP) patients with acceptable safety. After treatment of ALC in diabetic subgroup presented a significant decreased in Visual Analogue Scale (VAS) scores and less significant reduction in VAS scores was observed in non-diabetic group compared with those receiving placebo.
Peripheral neuropathic pain (PNP) leads to an unpleasant experience due to lesion of peripheral nerves, which may be a result of a complication of diabetes mellitus, drug adverse effect, or other origins.
Peripheral neuropathic pain (PNP) leads to an unpleasant experience due to lesion of peripheral nerves, which may be a result of a complication of diabetes mellitus, drug adverse effect, or other origins. PNP substantially influences the quality of life. Despite a high cost of medication and potential adverse effects, treatment outcomes remain poor in many patients. Exploring new agents for PNP is thus compelling.
Acetyl-L-carnitine (ALC) is a fundamental compound helping in metabolism of fatty acids in mitochondria and in modulation of nerve growth factors and neurotransmitters in the nervous system. ALC has been tried in diabetic and non-diabetic peripheral neuropathy, but the effects remain controversial. Therefore, we conducted a systematic review of randomized controlled trials (RCTs) to evaluate the efficacy and safety of ALC compared with placebo or other active medications in treating diabetic and non-diabetic PNP.
- Rationale behind research
- Despite a high cost of medication and potential adverse effects, treatment outcomes remain poor in many patients.
- The effects of ALC remain controversial. So, this study was conducted to evaluate the efficacy and safety of ALC compared with other active medications.
To evaluate the efficacy and safety of ALC for the treatment of patients with PNP.
- Effect of ALC on pain (VAS score)
- No significant statistical heterogeneity was present among the studies (I2 = 42%, P = 0.16), random-effects model was used for analysis due to different participants
- Pooled results showed that ALC slightly reduced pain compared to placebo with statistical significance (MD of VAS, 1.20; 95% CI, 0.68–1.72, P < 0.00001)
- In diabetic subgroup, patients receiving ALC had a significant decreased in VAS scores compared to placebo (MD, 1.47; 95% CI, 1.06–1.87, P <0.00001)
- A less significant reduction of VAS scoring was observed in non-diabetic group (MD, 0.71; 95% CI, -0.01–1.43, P = 0.05)
- A subgroup analysis was also conducted, according to the route of ALC administration. The effects on VAS scores were similar between the two subgroups: oral administration subgroup (MD, 1.15; 95%CI, 0.33–1.96, P = 0.006) and sequential administration subgroup (MD, 1.19; 95% CI, 0.34–2.04, P = 0.006)
- Adverse events
There was no statistically significant difference in the incidence of adverse events between treatment groups
The current evidence suggests that ALC seems effective and safe for treating PNP, especially of diabetic PNP. Oral administration of ALC may be recommended due to its similar efficacy but easier administration. However, further trials with larger and various population and longer follow-up are needed.
There has not been a systematic review published that specifically addresses the effect of ALC for PNP. We thus have systematically collected all relevant RCTs, and our results suggested that ALC is effective and safe for alleviating pain of PNP patients. The current meta-analysis indicated ALC reduce VAS with statistical significance. According to the subgroup analysis, patients with diabetic neuropathic pain appeared to have a better response from ALC compared with those due to a non-diabetic cause, which is consistent with recent systematic reviews. The effective dose of ALC could not be concluded yet so further evaluation different doses of ALC are necessary. Our results also indicated ALC was a safe agent without additional adverse effect compared with placebo.