A simple sensitive spectrophotometric method is described for determination of six drugs with different n-donating groups. These drugs are azithromycin (I), ketoconazole (II), clotrimazole (III), clozapine (IV), oxamniquine (V), and pimozide (VI). The method depends on the interaction of these compounds with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as π acceptor to form highly colored reaction product. The analytical wavelength chosen is 588 nm which gives maximum sensitivity. Optimum conditions for the reaction were determined and the mean percentage recoveries were 99.79 ± 0.65, 100.44 ± 1.03, 100.12 ± 0.66, 99.60 ± 0.8,99.74 ± 0.65 and 100.29 ± 0.79 for I, II, III, IV, V and VI, respectively. Study of the reaction product showed that charge transfer complex (CT) primarily formed dissociates to give radical anion with λmaxat 429 nm. The effect of basic properties of the studied drugs, on the production of radical anion, was illustrated by determining the yield percentage and confirmed through the calculation of the rate constant (K) and the association constant (KCTAD).