The U.S. Food and Drug Administration today approved Zepatier (elbasvir and grazoprevir) with or without ribavirin for the treatment of chronic hepatitis C virus (HCV) genotypes 1 and 4 infections in adult patients.

Hepatitis C is a viral disease that causes inflammation of the liver that can lead to diminished liver function or liver failure. Most people infected with HCV have no symptoms of the disease until liver damage becomes apparent, which may take several years. Some people with chronic HCV infection develop cirrhosis over many years, which can lead to complications such as bleeding, jaundice (yellowish eyes or skin), fluid accumulation in the abdomen, infections or liver cancer. According to the Centers for Disease Control and Prevention, approximately 3 million Americans are infected with HCV, of which genotype 1 is the most common and genotype 4 is one of the least common.

"Today's approval provides another oral treatment option for patients with genotypes 1 and 4 HCV infections without requiring use of interferon," said Edward Cox, M.D., director of the Office of Antimicrobial Products in the FDA's Center for Drug Evaluation and Research.

The safety and efficacy of Zepatier with or without ribavirin was evaluated in clinical trials of 1,373 participants with chronic HCV genotype 1 or 4 infections with and without cirrhosis. The participants received Zepatier with or without ribavirin once daily for 12 or 16 weeks. The studies were designed to measure whether a participant's hepatitis C virus was no longer detected in the blood 12 weeks after finishing treatment (sustained virologic response or SVR), suggesting a participant's infection had been cured.

The overall SVR rates ranged from 94-97 percent in genotype 1-infected subjects and from 97-100 percent in genotype 4-infected subjects across trials for the approved treatment regimens. In order to maximize SVR rates for patients, the product label provides recommendations regarding length of treatment with or without ribavirin specifically tailored to the characteristics of the patient and their virus. It is recommended that healthcare professionals screen genotype 1a-infected patients for certain viral genetic variations prior to starting treatment with Zepatier to determine dosage regimen and duration.

The most common side effects of Zepatier without ribavirin were fatigue, headache and nausea. The most common side effects of Zepatier with ribavirin were anemia and headache.

Zepatier carries a warning alerting patients and health care providers that elevations of liver enzymes to greater than five times the upper limit of normal occurred in approximately 1 percent of clinical trial participants, generally at or after treatment week eight. Liver-related blood tests should be performed prior to starting therapy and at certain times during treatment.  Zepatier should not be given to patients with moderate or severe liver impairment.

Zepatier was granted  breakthrough therapy designation for the treatment of chronic HCV genotype 1 infection in patients with end stage renal disease on hemodialysis and for the treatment of chronic HCV genotype 4 infection. Breakthrough therapy designation is a program designed to expedite the development and review of drugs that are intended to treat a serious condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over available therapy on a clinically significant endpoint.

Zepatier is marketed by Merck & Co. Inc. based in Whitehouse Station, New Jersey.

The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation's food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.