Simultaneous determination of verapamil and celiprolol in human plasma.

A simple and reproducible method for the simultaneous determination of the beta 1-selective adrenergic blocker, celiprolol, and the calcium antagonist, verapamil, in human plasma is described. It involves a two-step liquid-liquid extraction and separation using a C18 column with ultraviolet detection at 237 nm. Deacetyldiltiazem is used as the internal standard. Within-day and between-day coefficients of variation are less than 10%. The lower limits of detection are 4, 2, and 4 ng/mL for celiprolol, deacetyldiltiazem, and verapamil, respectively. The assay has clinical applicability.