Abstract The exposure of drugs to light produces photodecomposition processes in several cases: the drugs undergo important chemical changes with a parallel change in their activities or potencies and generally with a loss of their therapeutical actions. Generally, the chemical change in the molecule involves the reduction or oxidation of one photoactive group, producing a change in the redox behaviour of the molecule. Therefore electrochemical techniques can play an important role in the determination of light degradative processes in drugs. Specifically, in this work, we apply the polarographic technique to a study of the photodegradation process of some calcium antagonists of the dihydropyridine family. The degradation kinetics due to three light exposure conditions are reported.