Verapamil increased the systemic exposure of rivaroxaban by 2.8-fold (p<0.001) and proportionally prolonged prothrombin time in rats, whereas diltiazem had no significant effects.
Effect estimate: 2.8-fold increase
p-value: p=<0.001
Concomitant use of rivaroxaban with non-dihydropyridine calcium channel blockers (non-DHPs) might lead to an increase of systemic rivaroxaban exposure and anticoagulant effects in relation to the inhibition of metabolic enzymes and/or transporters by non-DHPs. This study was designed to evaluate the effects of verapamil and diltiazem on the pharmacokinetics and the prolongation of prothrombin time of rivaroxaban in rats. The data were analyzed using a pharmacokinetic/pharmacodynamics (PK/PD) modeling approach to quantify the influence of verapamil. Verapamil increased the systemic exposure of rivaroxaban by 2.8-fold (p <0.001) which was probably due to the inhibition of efflux transportation rather than metabolism. Prothrombin time was also prolonged in a proportional manner; diltiazem did not show any significant effects, however. A transit PK model in the absorption process comprehensively describes the double-peaks of rivaroxaban plasma concentrations and the corresponding change of prothrombin time with a simple linear relationship. The slope of prothrombin time vs. rivaroxaban plasma concentration in rats was retrospectively found to be insensitive by about 5.4-fold compared to than in humans. More than a 67% dose reduction in rivaroxaban is suggested in terms of both a pharmacokinetic point of view, and the sensitivity differences on the prolongation of prothrombin time when used concomitantly with verapamil.
Kim et al. (2019) studied this question. Verapamil and diltiazem was evaluated on Systemic exposure of rivaroxaban and prolongation of prothrombin time (2.8-fold increase, p=<0.001). Verapamil increased the systemic exposure of rivaroxaban by 2.8-fold (p<0.001) and proportionally prolonged prothrombin time in rats, whereas diltiazem had no significant effects.