OBJECTIVETo study the pharmacokinetics of lipoic acid in guinea pig perilymph and to provide experimental evidence for clinical delivery methods and dose in order to compare of intravenous and intratympanic administration using high-performance liquid chromatography (HPLC).

METHODSFifty-four guinea pigs were randomly divided into two groups of intratympanic and intravenous administration, with 27 ones in each group, and the concentration of lipoic acid was 100 mg/ml. The concentration of lipoic acid in perilymph was detected respectively by HPLC at 0.5, 1, 2, 3, 4, 5, 6, 8 and 10 h after administration.

RESULTSA well linear relation of concentration of lipoic acid in perilymph was shown when the concentration was detected from 0.1 to 200 microg/ml (r(2) = 0.9996). The maximum of concentration of lipoic acid administrated via intratympanic was 171.7 microg/ml, and via intravenous was 33.7 microg/ml; the MRT of intratympanic injection was 3.7 h while intravenous injection was 2.9 h; the half life (t(1/2)) of the former was 1.8 h but the latter was 2.1 h.

CONCLUSIONSThe drug concentration could both be detected via intravenous and intratympanic injection in perilymph of guinea pig, But the effect of local administration via intratympanic was obvious superior to systemic administration.