Coadministration with Viekirax alone has not been studied but a similar effect is expected as observed with Viekirax + dasabuvir due to inhibition of CYP3A4 by ritonavir. Coadministration of amlodipine (5 mg single dose) with Viekirax + dasabuvir increased amlodipine Cmax by 26% and increased AUC by 2.57-fold. There was no change ombitasvir Cmax, AUC or Cmin. Paritaprevir Cmax, AUC and Cmin decreased by 23%, 22% and 12%, respectively. Decrease amlodipine dose by 50% and monitor patients for clinical effects.
Viekirax Summary of Product Characteristics, AbbVie Ltd, January 2015.