A series of alkyl, cycloalkyl, and aryl esters of nifedipine in which the o-nitrophenyl group at position 4 is replaced by 2-(4-chlorophenyl)-4-thiazolyl substituent were synthesized and evaluated for their calcium channel antagonist activities using isolated ileum of guinea pig. The anticonvulsant activity of test drugs was also assessed in pentylenetetrazole (PTZ)-induced seizure in male Naval Medical Research Institute (NMRI) mice model. The results showed that although all compounds were at least 100 times less active than the reference drug nifedipine in terms of calcium channel antagonist activity, nevertheless all compounds showed considerable anticonvulsant activity.