Abstract: AIM: To establish a simple HPLC method for determining flunarizine hydrochloride in humanPlasma and to study bioequivalence between twoPreparations.METHODS: The drug and internal standard(diazepam)were extracted from thePlasma with n-hexane.The HPLC method wasPerformed with a diamonsil C18 column,and the mobilePhase was 0.06 mol·L^-1sodium acetate(pH =3.76)-acetonitrile(45∶55).The flow rate was 1.0 ml·min^-1and the wavelength was 254 nm.The data obtained were fitted with 3p97Program on computer to evaluate the bioequivalence.RESULTS: The calibration curve waslinear in the range of 2.5 -160μg·L^-1(r =0.9989).The minimum detection concentration was 2.5μg·L^-1.The values of AUC,C_max,T_max,and t_1/2βof twoPreparations had no significant difference(P>0.05).The relative bioavailability was(98.41±11.23)%(n =20).CONCLUSION: This HPLC method is simple,and twoPreparations of flunarizine hydrochloride are bioequivalent.

Key words: pharmacology, flunarizine hydrochloride, HPLC, pharmacokinetics, bioavailibility, bioequivalent