The Effect of L-Carnitine on Wound Healing in an Animal Model
Objectives: L-carnitine [(CH₃)₃-N-CH₂-CHOH-CH₂-COO-] is an amino acid derivative found in high energy demanding tissues. It plays an active role under low oxygen conditions. The authors studied the effect of L-carnitine on wound healing by secondary intention on full-thickness surgical skin defects in an animal model.
Materials and Methods: Twenty-two Sprague-Dawley rats were divided into 2 groups. A 4-cm diameter circular full-thickness surgical skin defect was created on the dorsum of each rat and was left to heal by secondary intention. L-carnitine was given intraperitoneally at a dose of 100mg/kg once daily to the study group for 10 days. The control group was injected intraperitoneally with saline (0.09% NaCl) only. On the 11th day, the skin defects were traced on a transparent sheet, and the unhealed areas were measured using planimetry.
Results: The areas of skin defects measured at the end of the study were not significantly different between the 2 groups ( p >0.05). On the 11th day, the median of the defect area of the study group was 2.7cm, whereas that of the control group was 3.4cm.
Conclusion: Although there was a tendency toward faster healing in the group receiving the drug, L-carnitine was not shown to significantly promote wound healing by secondary intention in an animal model. Further studies using different models, dosages, and durations of treatment are necessary to elucidate any possible effect.

Full-thickness skin defects consist of loss of the entire epidermis and underlying dermis. This type of wound tends to heal by secondary intention in which contraction and angiogenesis, in addition to epithelization, gain importance. In this type of healing, inflammatory reaction is more intense, and larger amounts of granulation tissue form compared with healing by primary intention. The increased contribution of myofibroblasts supports the contraction that takes place in this healing process. Additionally, circulatory and metabolic status is important in influencing wound closure.

L-carnitine [(CH₃)₃-N-CH₂-CHOH-CH₂-COO-] is an endogenous cofactor in the shuttle mechanism to transport long-chain fatty acids into the mitochondria where they undergo ß-oxidation. Through the reaction hydrolyzed by carnitine acetyltransferase, carnitine produces free coenzyme A (CoA) for other metabolic reactions and reduces the ratio of acetylCoA to CoA, which stimulates pyruvate dehydrogenase to enhance oxidative use of glucose, reducing lactate production and acidosis. L-carnitine is essential in providing efficient regulation of energy flow from different oxidative sources. During ischemia, this regulation is not possible. Excess acetylCoA esters accumulate, a larger amount of carnitine is required to remove them, and secondary carnitine deficiency develops. Tissue carnitine is progressively lost as the ischemic process advances.

L-carnitine or its derivatives have been used in the treatment of angina pectoris, acute myocardial infarction, postmyocardial infarction, congestive heart failure, peripheral vascular disease, dyslipidemia, diabetes, and chronic renal diseases. Satisfactory improvements have been achieved in cellular function and organ performance. Moreover, it was shown previously that carnitine had a significant dose-dependent effect to promote random pattern skin flap survival.

To the authors' knowledge, this is the first study that attempts to elucidate any possible positive effect of L-carnitine on healing of full-thickness skin defects in rats.