From: The Plasma Pharmacokinetics of R-(+)-Lipoic Acid Administered as Sodium R-(+)-Lipoate to Healthy Human Subjects.
Different forms of RLA produce dramatically different PK values. Recently, RLA was compared to NaRLA in humans using a simple crossover design.43 This study compared Cmax and AUC values of a pre-dissolved aqueous solution containing 600 mg RLA (as NaRLA) to those of 600 mg RLA in the same subjects. In a single male (subject 1), NaRLA produced Cmax of 14.1 mcg/mL; whereas, RLA resulted in a Cmax of 0.7 mcg/mL (increase of 25.86x). The AUC in the same subject was 5.18 mcg hr/mL for NaRLA versus 1.56 mcg hr/mL for RLA (increase of 3.3x). In a single female (subject 4), Cmax was 18.1 mcg/mL for NaRLA versus 1.01 mcg/mL for RLA (increase of 17.9x) and the AUC was 5.71 mcg hr/mL for NaRLA compared to 2.14 mcg hr/mL for RLA (increase of 2.67x).