The aim of the present study was to compare the bioavailability of clindamycin (CAS 18323-44-9) from three clindamycin hydrochloride (CAS 21 462-39-5) capsules (clindamycin 75 mg capsule as test 1 preparation, 150 mg capsule as test 2 preparation and a commercially available original 150 mg capsule of the drug as reference preparation) in 24 Chinese healthy male volunteers, aged between 22 and 28. The study was conducted according to a randomized, double-blind, 3-period, 3-treatment, 3-sequence, single-dose, crossover design with a wash-out phase of 7 days. Blood samples for pharmacokinetic profiling were taken up to 14 h post-dose, and clindamycin plasma concentrations were determined with a validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. Maximum plasma concentrations (C(max)) of 3.06 +/- 1.10 microg/mL (test 1), 3.10 +/- 1.59 microg/mL (test 2) and 3.06 +/- 1.15 microg/mL (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 10.73 +/- 4.29 microg x h/mL (test 1), 10.54 +/- 4.10 microg x h/ mL (test 2) and 11.29 +/- 4.98 microg x h/mL (reference), AUC(0-t) of 10.32 +/- 4.09 microg x h/ mL, 10.26 +/- 3.96 microg x h/mL, 10.94 +/- 4.86 g x h/mL were calculated. The median T(max) was 0.80 +/- 0.52 h, 0.77 +/- 0.37 h, 1.01 +/- 0.6 h for test 1, test 2 and reference formulation, respectively. Plasma elimination half-lives (t1/2) of 2.72 +/- 0.58 h (test 1), 2.39 +/- 0.37 h (test 2) and 2.63 +/- 0.66 h (reference) were determined. Both primary target parameters, AUC(0-infinity) and AUC(0-t) were tested parametrically by analysis of variance (ANOVA) and relative bioavailabilities were 98.0 +/- 16.2% (test 1) and 97.2 +/- 20.3% (test 2) for AUC(0-infinity), 97.5 +/- 16.3% (test 1) and 97.8 +/- 20.2% (test 2) for AUC(0-t). Bioequivalence between test and reference preparation was demonstrated for both parameters, AUC(0-infinity) and AUC(0-t). The 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%. That means that the two test formulations are bioequivalent to the reference formulation for clindamycin.