OBJECTIVE To study the pharmacokinetics and relative bioavailability of diltiazem hydrochloride controlled-release (DTZ-CR) capsule in healthy male volunteers.METHODS Diltiazem tablet was used as the refereace.A crossover self-control study of single and multiple dose was conducted on 12 healthy volunteers.Plasma concentrations were determined by HPLC.RESULTS The pharmacokinetic parameters after a single dose of 60 mg DTZ-CR capsule were: AUC_0→τ=(637.56±106.18) h·μg·L^-1,c_max=(59.5±8.0) μg·L^-1，t_max(4.5±0.5) h,t_1/2=(5.9±1.1) h,respectively.The relative bioavailability was (106.39±12.53)%.The degree of fluctuation for steady state of multipledoses was (0.89±0.11) μg·L^-1，which were significantly lower than that of the reference tablet.CONCLUSION The two formulations were of bioequivalence and DTZ-CR capsule had marked characteristics of controlled release.