Cardiovascular Risk Management and Hepatitis C: Combining Drugs

Direct-acting antivirals (DAAs) are known victims (substrate) and perpetrators (cause) of drug–drug interactions (DDIs). These DAAs are used for the treatment of hepatitis C virus (HCV) infections and are highly effective drugs. Drugs used for cardiovascular risk management are frequently used by HCV-infected patients, whom also are treated with DAAs. Therefore, the aim of this review was to describe DDIs between cardiovascular drugs (CVDs) and DAAs. An extensive literature search was performed containing search terms for the marketed DAAs and CVDs (β-blocking agents, ACE inhibitors, angiotensin II antagonists, renin inhibitors, diuretics, calcium channel blockers, statins/ezetimibe, fibrates, platelet aggregation inhibitors, vitamin K antagonists, heparins, direct Xa inhibitors, nitrates, amiodarone, and digoxin). In particular, the drug labels from the European Medicines Agency and the US Food and Drug Administration were used. A main finding of this review is that CVDs are mostly victims of DDIs with DAAs. Therefore, when possible, monitoring of pharmacodynamics is recommended when coadministering these drugs with DAAs. Nevertheless, it is sometimes better to discontinue a drug on a temporary basis (statins, ezetimide). The DAAs are victims of DDIs in combination with bisoprolol, carvedilol, labetalol, verapamil, and gemfibrozil. Despite there are many DDIs predicted in this review, most of these DDIs can be managed by monitoring the efficacy and toxicity of the victim drug or by switching to another CVD/DAA.

Influence of Successful Chronic Hepatitis C Virus Treatment with Ledipasvir/Sofosbuvir on Warfarin Dosing Requirements in Four Veterans

STUDY OBJECTIVE

To describe international normalized ratio (INR) trends and warfarin dosage adjustments required for four veterans who were receiving warfarin therapy and started treatment for hepatitis C virus (HCV) with ledipasvir/sofosbuvir with or without ribavirin.

DESIGN

Case series.

SETTING

Pharmacist-led anticoagulation clinic in a Veterans Affairs Health Care System.

PATIENTS

Four patients aged 59-66 years who were receiving warfarin and had stable, therapeutic INRs and started ledipasvir/sofosbuvir therapy with or without ribavirin for HCV infection.

MEASUREMENTS AND MAIN RESULTS

All four patients developed subtherapeutic INRs after the addition of ledipasvir/sofosbuvir with or without ribavirin. An increase in weekly warfarin dose ranging from 14-67% was required, with changes in warfarin doses starting 2-3 weeks after ledipasvir/sofosbuvir initiation. Two patients required dose reductions after HCV treatment completion, whereas the other two did not. Use of the Drug Interaction Probability Scale indicated that the interaction between warfarin and ledipasvir/sofosbuvir was doubtful (score of 1 [two patients]) or possible (score of 4 [two patients]). The mechanism of this interaction is unknown but may be related to improvements in hepatic function during HCV treatment.

CONCLUSION

To our knowledge, this is the first case series describing a possible drug interaction between warfarin and ledipasvir/sofosbuvir (with or without ribavirin). Close monitoring is warranted when ledipasvir/sofosbuvir is initiated in patients receiving anticoagulation therapy with warfarin, especially those with evidence of cirrhosis prior to treatment. This is particularly important in the first month after starting treatment and the first month after completion. Failure to monitor and achieve therapeutic INR after HCV therapy completion may have the potential to result in adverse outcomes.