Abstract: Both verapamil pharmacokinetics and electrocardio graphic changes in 10 Chinese volunteers were studied after po 240 mg of verapamil sustained release tablet. A one compartment model with zero order absorption gave a better fitting to concentration-time data with values of r²>0.96. The main pharmacokinetic parameters obtained were: T_max, 5.9±1.6 h; C_max, 118.9±37.2 μg·5L^-1 ; T₁, 5.4±1.5 h; k₀, 30.5±17.5 μg·5L^-1 5h -1 ; T_1/2, 10.8 ±4.9 h; MRT, 15.4±3.2 h and AUC. 1.96±0.82 mg·5h·5L^-1 . There were significant prolongations of PR intervals after dose. Relationships between PR interval changes and plasma concentrations of verapamil were better fitted to sigmoidal model, with r²>0.98. The corresponding pharmacodynamic parameters were estimated. EC₅₀ , 64.6±16.9 μg·5L^-1 , E_max, 54±11 ms and s, 1.68±0.66.