A 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile that has R configuration. It competitively inhibits the multidrug resistance efflux pump P-glycoprotein (MDR-1, EC 3.6.3.44), thereby potentially increasing the effectiveness of a wide range of antineoplastic drugs which are inactivated by MDR-1 mechanisms. Dexverapamil exhibits lower calcium antagonistic activity and toxicity than racemic verapamil. ChEBI: Dexverapamil is a 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile that has R configuration. It competitively inhibits the multidrug resistance efflux pump P-glycoprotein (MDR-1, EC 3.6.3.44), thereby potentially increasing the effectiveness of a wide range of antineoplastic drugs which are inactivated by MDR-1 mechanisms. Dexverapamil exhibits lower calcium antagonistic activity and toxicity than racemic verapamil. It has a role as an EC 3.6.3.44 (xenobiotic-transporting ATPase) inhibitor. It is a conjugate base of a dexverapamil(1+). It is an enantiomer of a (S)-verapamil.