Comparison of R(+)-α-lipoic acid exposure after R(+)-α-lipoic acid 200 mg and 300 mg and thioctic acid 600 mg in healthy Korean male subjects

Alpha-lipoic acid, a physiological form of thioctic acid, is a strong antioxidant that relieves diabetic neuropathic symptoms. R(+)-α-lipoic acid shows superior antioxidative effects to its racemate. We compared the pharmacokinetics (PKs) and tolerability of R(+)- and S(-)-α-lipoic acid after a single oral dose of R(+)-α-lipoic acid, Dexid®, and its racemate, thioctic acid in healthy male subjects. We used an open-label, randomized, single-dose, three-treatment, parallel study design to compare the PK exposure of the active form, R(+)-α-lipoic acid. Thirty subjects completed the study with no clinically relevant safety issues. The peak concentrations (C(max), mean±SD) of R(+)-α-lipoic acid after doses of R(+)-α-lipoic acid 200 mg, 300 mg and thioctic acid 600 mg were 4186.8±1956.7, 6985.6±3775.8 and 6498.4±3575.6 µg/L, respectively, and the areas under the plasma concentration-time curve from 0 to the last measurable concentration (AUC(last)) were 1893.6±759.4, 3575.2±1149.2 and 3790.0±1623.0 µg·h⁻¹·L⁻¹, respectively. The geometric mean ratio and 90% confidence intervals of R(+)-α-lipoic acid 200 mg to thioctic acid 600 mg for the C(max) and AUC(last) were 0.71 (0.43–1.15) and 0.51 (0.37–0.70), respectively. The corresponding R(+)-α-lipoic acid 300 mg to thioctic acid 600 mg values were 1.11 (0.68-1.80) and 0.97 (0.71-1.34), respectively. In conclusion, R(+)-α-lipoic acid 300 mg showed PK characteristics similar to those of thioctic acid 600 mg and both formulations were well tolerated.

Stereoisomerism(Chirality) of Psychotropic Drugs / 대한정신약물학회지

Many psychotropic drugs are marketed and prescribed as a racemate form in a mixture of the stereoisomers. A chiral center or a center of unsaturation of carbon atoms in the chemical structures creates various stereoisomers of the psychotropic drugs, including antidepressants such as fluoxetine and venlafaxine, etc. The stereochemical significances of enantiomers on the pharmacokinetics and pharmacodynamics of several psychotropic drugs and their relationships with pharmacogenetic polymorphisms were reviewed. The single enantiomer drugs will be increasing more in the market shares replacing the racemic drugs by chiral switching, which is driven by the development of the analytical and preparative resolution techniques and will be of much benefit to the treatment from low dosages, simple dose-response curve, few adverse reactions, and so on.