AbbVie Inc said on Wednesday that its hepatitis C cocktail Viekira Pak was effective whether or not it was used in combination with the compound ribavirin against the most common form of the disease, according to data from a late-stage study.

Viekira Pak, a combination of the drugs Viekirax and Exviera, was approved in December for use as both a standalone treatment and in tandem with ribavirin, a broad-spectrum antiviral approved in 1998.

All the patients in the study showed a sustained response to Viekira Pak as a standalone treatment after 12 weeks of treatment, AbbVie said.

The late-stage study on which the U.S. Food and Drug Administration based its decision to approve Viekira Pak in December showed it cured 91-100 percent of all patients with the infection.

Viekira Pak is one of three treatments for the liver-scarring disease fighting to corner the lion's share of the multi-billion dollar market and competes with Gilead Sciences Inc's Sovaldi and Harvoni, and Johnson & Johnson's Olysio.