Anti-HCV agent, ribavirin, elevates the activity of clotting factor VII in patients with hemophilia: a possible mechanism of decreased events of bleeding in patients with hemophilia by ribavirin

Increased warfarin requirements in a patient with chronic hepatitis C infection receiving sofosbuvir and ribavirin

PURPOSE

A case of increased warfarin requirements during treatment with sofosbuvir and ribavirin for chronic hepatitis C virus (HCV) infection is reported.

SUMMARY

A 63-year-old white man receiving long-term anticoagulation with warfarin for atrial fibrillation and a history of cardioembolic stroke was initiated in September 2014 on a 12-week course of sofosbuvir 400 mg orally daily and weight-based ribavirin 600 mg orally twice daily for HCV genotype 2 infection. Before starting this treatment regimen, the patient had been stable on warfarin 52.5 mg weekly, with therapeutic International Normalized Ratio (INR) values. During the 12-week course of sofosbuvir and ribavirin, the patient's dose of warfarin progressively increased from 52.5 to 77.5 mg weekly due to subtherapeutic INRs, with the first adjustment in the warfarin dose occurring 9 days after initiation of HCV treatment. Three weeks after completion of the sofosbuvir and ribavirin regimen, the patient's INR was 3.06, and his warfarin dose was then decreased to 70 mg weekly. The patient continued with this warfarin dosage until 18 weeks after completion of his HCV regimen. The dosage was then decreased to 65 mg weekly after an INR of 3.86. Three weeks later, his INR was 2.19, and warfarin 65 mg weekly was continued. As of June 2016, the patient has continued to require warfarin 62.5-65 mg weekly to maintain a therapeutic INR.

CONCLUSION

A 63-year-old man on a stable dose of warfarin experienced a decrease in INR values after the initiation of a 12-week course of sofosbuvir and ribavirin for the treatment of chronic HCV infection.

Paritaprevir/ritonavir/ombitasvir+dasabuvir plus ribavirin therapy and inhibition of the anticoagulant effect of warfarin: a case report

WHAT IS KNOWN AND OBJECTIVE

Paritaprevir/ritonavir/ombitasvir+dasabuvir (PrOD) is a direct-acting antiviral (DAA) approved for the treatment of chronic hepatitis C virus. We report on a probable interaction between PrOD with ribavirin and warfarin.

CASE DESCRIPTION

Two weeks after the start of PrOD with ribavirin, the patient's international normalized ratio (INR) became subtherapeutic. Eleven weeks into therapy and following a 125% total increase in the weekly warfarin dose, therapeutic INR was achieved. Thirteen days after DAA therapy was completed and discontinued, the patient's INR became critically supratherapeutic.

WHAT IS NEW AND CONCLUSION

Patients on PrOD plus ribavirin with warfarin should have INR followed closely upon initiation and discontinuation of therapy due to a probable drug interaction.

Evaluation of a Potential Interaction Between New Regimens to Treat Hepatitis C and Warfarin

OBJECTIVE

New regimens to treat hepatitis C virus infection have expanded the eligible patient population to include more patients receiving concurrent warfarin. The primary objective of this study was to assess whether a drug interaction occurs when these regimens are added to warfarin therapy.

METHODS

This was a retrospective cohort design using a nationwide database of the Veterans Affairs Health System. Patients on warfarin therapy treated with sofosbuvir or ombitasvir, paritaprevir-ritonavir, and dasabuvir (OBV-PTV/r-DSV) from March 2014 through October 2015 were identified. The warfarin dose response was calculated using a warfarin sensitivity index (WSI) defined as the steady-state INR divided by the mean daily warfarin dose. The primary outcome was the change in WSI from hepatitis C treatment initiation to completion.

RESULTS

The final sample consisted of 271 patients. The WSI decreased 23% from a mean baseline value of 0.53 to 0.39 (decrease of 0.14; 95% CI = 0.11 to 0.16; P < 0.001). OBV-PTV/r-DSV produced a significantly greater decrease than any sofosbuvir regimen. Concurrent ribavirin accounted for an additional decrease in warfarin sensitivity of -0.09 (95% CI = -0.06 to -0.12; P < 0.001). The percentage of subtherapeutic INR results increased from 26% prior to hepatitis C treatment to 58% during treatment.

CONCLUSIONS

Results indicate a clinically significant reduction in warfarin dose-response when hepatitis C treatment regimens were added to warfarin. They were most profound with OBV-PTV/r-DSV. Ribavirin was associated with an additive effect. Clinicians should be aware of this potential drug interaction to closely monitor and minimize subtherapeutic levels of anticoagulation.

Warfarin and boceprevir interaction causing subtherapeutic international normalized ratio: a case report

INTRODUCTION

Chronic hepatitis C is a leading cause of severe liver disease. Protease inhibitors used to treat these patients are known to have many drug interactions, although there is limited data available between boceprevir and warfarin. This case report is the first in vivo drug interaction reported in the literature.

CASE PRESENTATION

A 73-year-old African American man was diagnosed with hepatitis C in 2004, and had decided to not initiate therapy. In 2006, he was diagnosed with deep vein thrombosis and pulmonary embolism and was started on warfarin. His international normalized ratio had been stable on a dose of 13.75 mg to 20mg/week over a period of 6 years. A liver biopsy in 2012 revealed marked fibrosis, leading the patient to start hepatitis C treatment with peginterferon alfa-2a, ribavirin and boceprevir. Three weeks after starting boceprevir, his international normalized ratio became subtherapeutic at 1.2. Upon increasing the warfarin dose by 16%, his international normalized ratio remained at 1.2 6 days later. Two months after initiating boceprevir, he reached a therapeutic international normalized ratio. His warfarin dose had been increased by 75% from his dose prior to starting boceprevir, from 15 mg/week to 26.25mg/week. His hepatitis C treatment was discontinued at week 39 of the intended 48 weeks of treatment due to severe thrombocytopenia. Upon discontinuation of boceprevir, his warfarin dose was prophylactically decreased by 17%, which resulted in a subtherapeutic international normalized ratio of 1.48 1 week later. The warfarin dose was subsequently increased by 10% which resulted, 2 weeks later, in a therapeutic international normalized ratio of 2.8. Once stabilized, his new warfarin dose was 23.75 mg/week, 37% higher than his original maintenance dose of 15 mg/week prior to starting boceprevir.

CONCLUSIONS

The co-administration of boceprevir and warfarin resulted in a subtherapeutic international normalized ratio. Upon starting boceprevir, his warfarin dose was increased by 75% over 2 months to achieve a therapeutic international normalized ratio. After discontinuing boceprevir, his maintenance dose of warfarin was 37% greater than his original dose. This is an original case report which demonstrates the significant effects of this drug interaction and the importance of monitoring international normalized ratio.

Overexpression of factor VII ameliorates bleeding diathesis of factor VIII-deficient mice with inhibitors

INTRODUCTION

Factor VIII (FVIII) treatment for hemophilia A has difficulties in correcting bleeding diathesis in the presence of inhibitors.

MATERIALS AND METHODS

An adeno-associated virus type 8 (AAV8) vector containing the factor VII (FVII) gene or the activated factor VII (FVIIa) gene was used to investigate the therapeutic effect of FVII or FVIIa overexpression in FVIII-deficient mice with inhibitors.

RESULTS

Following repeated human FVIII injection, FVIII-deficient mice developed anti-human FVIII antibodies that cross-reacted with mouse FVIII. High transgene expression of murine FVII or murine FVIIa was achieved using the AAV8 vector and resulted in increased blood FVII activity greater than 800% of normal murine FVII levels in vector-injected FVIII-deficient mice. Thromboelastography analysis showed significant improvements in clotting time, clot formation time, α angle, and mean clot firmness in AAV8 vector-injected FVIII-deficient mice with inhibitors. Overexpression of FVIIa ameliorated the bleeding phenotype of FVIII-deficient mice with inhibitors and significantly increased the survival rate after tail clipping. In addition, overexpression of FVII increased the survival rate of FVIII-deficient mice with inhibitors after tail clipping though it was not as efficient as FVIIa overexpression.

CONCLUSIONS

These data suggest that FVII overexpression is an alternative strategy for the treatment of hemophilia A with inhibitors.

Ribavirin-induced intracellular GTP depletion activates transcription elongation in coagulation factor VII gene expression

Coagulation FVII (Factor VII) is a vitamin K-dependent glycoprotein synthesized in hepatocytes. It was reported previously that FVII gene (F7) expression was up-regulated by ribavirin treatment in hepatitis C virus-infected haemophilia patients; however, its precise mechanism is still unknown. In the present study, we investigated the molecular mechanism of ribavirin-induced up-regulation of F7 expression in HepG2 (human hepatoma cell line). We found that intracellular GTP depletion by ribavirin as well as other IMPDH (inosine-5'-monophosphate dehydrogenase) inhibitors, such as mycophenolic acid and 6-mercaptopurine, up-regulated F7 expression. FVII mRNA transcription was mainly enhanced by accelerated transcription elongation, which was mediated by the P-TEFb (positive-transcription elongation factor b) complex, rather than by promoter activation. Ribavirin unregulated ELL (eleven-nineteen lysine-rich leukaemia) 3 mRNA expression before F7 up-regulation. We observed that ribavirin enhanced ELL3 recruitment to F7, whereas knockdown of ELL3 diminished ribavirin-induced FVII mRNA up-regulation. Ribavirin also enhanced recruitment of CDK9 (cyclin-dependent kinase 9) and AFF4 to F7. These data suggest that ribavirin-induced intracellular GTP depletion recruits a super elongation complex containing P-TEFb, AFF4 and ELL3, to F7, and modulates FVII mRNA transcription elongation. Collectively, we have elucidated a basal mechanism for ribavirin-induced FVII mRNA up-regulation by acceleration of transcription elongation, which may be crucial in understanding its pleiotropic functions in vivo.

APASL consensus statements and management algorithms for hepatitis C virus infection

The Asian Pacific Association for the Study of the Liver (APASL) convened an international working party on the "APASL Consensus Statements and Management Algorithms for Hepatitis C Virus Infection" in December, 2010, in order to revise "Asian Pacific Association for the Study of the Liver consensus statements on the diagnosis, management and treatment of hepatitis C virus infection (J Gastroenterol Hepatol 22:615-633, 2007)". The working party consisted of expert hepatologists from the Asian-Pacific region gathered at Makuhari, Chiba, Japan on 19 December 2010. New data were presented, discussed and debated to draft a revision. Participants of the consensus meeting assessed the quality of cited studies. Finalized recommendations are presented in this review.

Chronic hepatitis C virus infection in children

The importance of hepatitis C viral infection in the health care of children has grown in recent decades. More is now known about the epidemiology of this infection in children and the progression of disease in the pediatric age group, and the treatment options are increasing. In this review, we update readers on the state of our understanding of hepatitis C infection in children, provide the current recommendations for monitoring and treatment, and discuss emerging therapies.