Simple, sensitive and accurate spectrophotometric and atomic absorption spectrometric procedures were developed for the determination of both diltiazem and dothiepin hydrochlorides in pure forms and in pharmaceutical preparations. The first method was based on the formation of ion-pair complexes between the two drugs and tropeolin oo using extractive procedures. The complex showed absorption maxima at 477 nm. Beer's Law was obeyed in the concentration range of (4-20) and (1.6-16) µgml^-1 for diltiazem and dothiepin hydrochlorides respectively.
The second method was based on formation of a ternary complex between (copper (II), rose bengal and drug). This complex was extracted with methylene chloride and measured at 555 nm. Beer's Law was obeyed in concentration range (24-80) and (16-32) µgml^-1 for diltiazem and dothiepin hydrochlorides, respectively. The third method depends on determination of copper content of the formed complex using atomic absorption procedure, Beer's Law was obeyed in concentration range (16-24) and (32-68) µg ml^-1 for dothiepin and diltiazem hydrochlorides respectively. The proposed methods hold their accuracy and precision welt when applied to the determination of diltiazem and dothiepin in their dosage forms.