Studies on the bioavailability of alpha lipoic acid in type I and type II diabetics with diabetic neuropathy

In a controlled randomized cross-over study with two parallel groups 24 type I and type II diabetics with diabetes-induced polyneuropathy were given alpha lipoic acid in two different dosages and methods of administration. Group A (12 patients) was given 600 mg of alpha lipoic acid administered intravenously as a defined short infusion and orally in tablet form. Group B (12 patients) was given 200 mg of alpha lipoic acid administered intravenously as a defined short infusion and orally in tablet form. The extent of the bioavailability (AUC) of free alpha lipoic acid in plasma after intravenously administering 600 mg of alpha lipoic acid was 13.1 μg/ml·h and after 200 mg was 2.2 μg/ml·h. After 600 mg of orally administered alpha lipoic acid the AUC was 2.1 μg/ml·h and after 200 mg it was 0.4 μg/ml·h. The AUC of the single dose of 600 mg administered intravenously and orally was thus about twice as high as the adjusted dosage AUC of 200 mg. This difference was statistically significant. These results support the recommended therapy plan of 600 mg intravenously followed by an oral maintenance therapy of 1 x 600 mg daily.