Chiral separation of Ibuprofen and chiral pharmacokinetics in healthy Chinese volunteers

A rapid, sensitive and stereoselective HPLC method based on chiral column analysis was developed and fully validated for the simultaneous determination of the two enantiomers of ibuprofen in human plasma. Using this method, a chiral pharmacokinetic study of two different ibuprofen tablets, i.e. dexibuprofen tablets and racemic ibuprofen tablets, was carried out on 20 healthy Chinese male volunteers according to a single-dose (400 mg), two-way, cross-over randomized design. When a 'non-chiral calculation method' was used, the statistical analysis showed no significant difference for the pharmacokinetic parameters (AUC_0-∞, AUC_0-t , C_max and t_max) between the two oral formulations, suggesting that they were pharmaceutically bioequivalent. Considering that the pharmacological activity of ibuprofen resides exclusively in the S(+)-enantiomer, and that the unidirectional inversion of the R(-) to the S(+)-enantiomer is incomplete and might be race-dependent, the pharmacokinetic parameters for only the S(+)-enantiomer were further compared and the inversion ratio calculated. It was found that only 25% of R(-)-ibuprofen in the racemic ibuprofen tablets was inverted into S(+)-ibuprofen in the Chinese population, which suggested that dexibuprofen might possess a much stronger pharmacological activity than that of racemic ibuprofen when administered at the same dose.