title: The pharmacodynamic and pharmacokinetic differences of the D- and L-isomers of verapamil: implications in the treatment of paroxysmal supraventricular tachycardia.
abstract: There is increasing interest in defining the pharmacodynamic and pharmacokinetic characteristics of drugs that are marketed as racemic mixtures. Verapamil is one such drug that is commercially available as a mixture of D- and L-isomers. The L-isomer of verapamil has a greater-negative inotropic, negative chronotropic, and negative dromotropic potency than the D-isomer. The values for fraction unbound in serum, distribution volume, and systemic clearance are substantially greater for the L-isomer after intravenous dosing. After oral dosing, the D-isomer achieves peak plasma concentrations five times greater than the L-isomer. The pharmacodynamic and pharmacokinetic characteristics of each isomer are reviewed. The differences in the concentrations of the D- and L-isomers after oral vs intravenous dosing may contribute to the relatively lower efficacy of orally administered verapamil in the treatment of PSVT.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013614:Tachycardia, Paroxysmal / Q000188:drug therapy*; D014700:Verapamil / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D014700:Verapamil