Felodipine(Fel) (ethylmethyl-4-(2,3-dichlorophenyl)-1,4-dihy-dro-2,6-dimethyl-3,5-pyridinedicarboxylate) has been chosen as the subject of this study. Being a calcium channel blocker, felodipine is widely used for treating hypertension. The choice of this compound can be explained by the following reasons.