Viekira Pak by AbbVie Inc

Viekira Pak is an all-oral regimen that has been approved by the FDA for the treatment of genotype 1 chronic hepatitis C virus infection.

On December 19, 2014, the FDA announced approval of Viekira Pak (ombitasvir, paritaprevir, and ritonavir tablets; dasabuvir tablets), an all-oral regimen for the treatment of genotype 1 (GT1) chronic hepatitis C virus (HCV) infection.¹ Although Viekira Pak does not carry any black box warnings, its use is not recommended in patients with decompensated liver disease. However, Viekira Pak may be used in patients with compensated cirrhosis.²

Contraindications for use of Viekira Pak include severe hepatic impairment and severe ritonavir hypersensitivity. Coadministration with medications dependent on CYP3A for clearance, strong CYP3A inducers, and strong CYP2C8 inducers or inhibitors is also contraindicated. Patients using Viekira Pak with ribavirin must also be evaluated for the contraindications associated with ribavirin.^2,3

Pharmacology and Pharmacokinetics

Mechanistically, the 3 components of Viekira Pak are classified as direct-acting antivirals. Each component has a distinct mechanism of action: ombitasvir is an HCV NS5A inhibitor; dasabuvir is a nonnucleoside NS5B polymerase inhibitor; and paritaprevir is a NS3/4A protease inhibitor that is used with ritonavir to enhance paritaprevir levels.²

Dosage and Administration

Each carton of Viekira Pak contains 28 days of therapy, split into 4 cartons supplying 7 days of therapy each. A single daily dose pack is composed of 2 types of tablets: 2 combination tablets containing 12.5 mg of ombitasvir, 75 mg of paritaprevir, and 50 mg of ritonavir; and 2 tablets of dasabuvir sodium containing 250 mg of dasabuvir each.²

Patients using Viekira Pak should take 2 combination tablets containing ombitasvir, paritaprevir, and ritonavir once daily every morning. Dasabuvir tablets should be taken twice daily, with 1 tablet taken in the morning and 1 in the evening. In most cases, Viekira Pak is used with ribavirin, with the total daily dose of ribavirin to be divided into 2 daily administrations with food. Patients weighing ≤75 kg should receive a 1000-mg total daily dose of ribavirin, and patients weighing >75 kg should receive a 1200-mg total daily dose of ribavirin.²

Treatment with Viekira Pak typically lasts 12 weeks. Exceptions include liver transplant recipients and patients with GT1a infection with cirrhosis, all of whom usually require 24 weeks of therapy. Although patients with GT1b hepatitis C without cirrhosis may receive Viekira Pak alone, co-therapy with ribavirin is recommended in other patient groups.²

Clinical Trials

Viekira Pak has been evaluated in more than 2000 patients enrolled in 4 double-blind trials and 2 open-label trials. In addition, the safety and efficacy of Viekira Pak has been established in patients who have received a liver transplant and in patients coinfected with GT1 HCV and HIV. In each trial, investigators evaluated rates of sustained viral response 12 weeks after the end of treatment (SVR12). In clinical trials, SVR12 rates averaged 91% to 100%, depending on the population (Table).²

Warnings and Precautions

Use of Viekira Pak with strong CYP3A4 inhibitors may increase concentrations of paritaprevir and ritonavir, and use of Viekira Pak with strong CYP2C8 inhibitors may increase concentrations of dasabuvir.²

Use of several medications is contraindicated in patients using Viekira Pak, including alfuzosin, pimozide, carbamazepine, phenytoin, phenobarbital, St. John’s Wort, rifampin, ergot derivatives, medications that contain ethinyl estradiol, gemfibrozil, lovastatin, simvastatin, efavirenz, triazolam, midazolam, and sildenafil (but only when used for pulmonary arterial hypertension).²

It is important to limit the maximum dosage of certain medications, such as ketoconazole (200 mg/day), rosuvastatin (10 mg/day), and pravastatin (40 mg/day). Dosage adjustment is also necessary for patients using cyclosporine and tacrolimus, as use of Viekira Pak will increase levels of immunosuppressive medications.²

Viekira Pak is a Pregnancy Category B medication, although it is often used with ribavirin, which is a Category X medication.³ Common adverse events with Viekira Pak, each of which occurred in at least 5% of patients, include nausea, pruritus, and insomnia. However, fatigue, nausea, pruritus, skin reactions, insomnia, and asthenia each occurred in at least 10% of patients receiving Viekira Pak with ribavirin.² For a complete discussion of potential adverse events and drug interactions with Viekira Pak, please consult the product package insert. SPT

References

• FDA approves Viekira Pak to treat hepatitis C [press release]. FDA website. www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm427530.htm. Accessed January 2015.
• Viekira Pak [package insert]. North Chicago, IL: AbbVie Inc; 2014.
• Copegus (ribavirin) tablets [package insert]. South San Francisco, CA: Genentech USA, Inc; 2013.

About the Author

Michael R. Page, PharmD, RPh, earned his PharmD from the Ernest Mario School of Pharmacy at Rutgers University. He has worked as a community pharmacist at CVS Pharmacy and is currently clinical editor in clinical and scientific affairs at Pharmacy Times.