Bioavailability of β-aescin from horse chestnut seed extract: Comparative clinical studies of two galenic formulations

Abstract

The bioavailability of β-aescin—the main active constituent of horse chestnut seed extract—in a nonretarded test medication in comparison with that in a retarded reference formulation was evaluated in 2 randomized crossover clinical trials involving 18 healthy volunteers each. Serum concentration/time curves derived under steady-state conditions and pharmacokinetic parameters measured during both studies showed no significant difference between absorption rates for the retarded versus nonretarded preparation. In the first study, investigators found a test-to-reference ratio of 1.06 (90% confidence interval [CI] range: 99–113) for the area under the curve (AUC; the primary outcome measure). Absorption rates were diminished during the night compared with daytime rates for both study preparations. In the second study, using AUC and maximum concentration (C_max) as the primary characteristics, investigators analyzed bioavailability based on the mean of 2 consecutive daytime periods and obtained estimates of 1.07 for AUC (90% CI range: 0.96–1.19) and 1.05 for C_max (90% CI range: 0.90–1.21). Bioequivalence of the test and reference drug preparations was thus established according to theNote for Guidance on the Investigation of Bioavaiiability and Bioequivalence. Both treatments were equally well tolerated.