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HealthDay News – There is a probable interaction between paritaprevir/ritonavir/ombitasvir+dasabuvir (PrOD) [Holkira Pak / Viekira Pak] plus ribavirin with warfarin, according to a case report published online in the Journal of Clinical Pharmacy and Therapeutics.
Gina M. Puglisi, PharmD., from VA Maine Healthcare System in Augusta, and colleagues present the case of a probable interaction between PrOD with ribavirin and warfarin in a 58-year-old patient with hepatitis C virus genotype 1a, who was treatment naive. The patient took outpatient medications, including warfarin for stroke risk reduction. The patient was initiated on PrOD with ribavirin for 12 weeks for hepatitis treatment.
The authors noted that the patient’s international normalized ratio (INR) became subtherapeutic 2 weeks after the start of PrOD with ribavirin. Therapeutic INR was achieved 11 weeks into therapy and following a 125% total increase in the weekly warfarin dose.
The patient’s INR became critically supratherapeutic 13 days after direct-acting antiviral therapy was completed and discontinued. A score of +7 was obtained using the Naranjo Nomogram, which indicated that the increase in INR for warfarin produced by PrOD with ribavirin was probable.
“Patients on PrOD plus ribavirin with warfarin should have INR followed closely upon initiation and discontinuation of therapy due to a probable drug interaction,” the authors wrote.
Reference
Puglisi GM, Smith SM, Jankovich RD, Ashby CR, Jodlowski TZ. Paritaprevir/ritonavir/ombitasvir+dasabuvir plus ribavirin therapy and inhibition of the anticoagulant effect of warfarin: a case report. J Clin Pharm Ther. 2016 Nov 3. doi:10.1111/jcpt.12475.