Verapamil's R isomer and its metabolite norverapamil have substantially less calcium channel blocking activity yet were similarly active as verapamil at inhibiting macrophage-induced drug tolerance.?Our finding that verapamil inhibits intracellular M. tuberculosis growth and tolerance suggests its potential for treatment shortening.?Norverapamil, R-verapamil, and potentially other derivatives present attractive alternatives that may have improved tolerability[1].

Norverapamil is?a major metabolite of verapamil, has terminal half-life, AUC and Cmax values of 9.4 hours, 260 ng?h/ml, and 41.6 ng/mL, respectively[2].