An experimental drug called telaprevir appears to cure far more people of hepatitis C than current treatments, two new studies have found.

The research found that when the anti-viral drug is added to the standard treatment for hepatitis C, not only are more patients cured, patients need to take medication for only six months rather than the usual year.

However, those taking the drug reported more side effects that those not using it. Those side effects included severe rash, nausea and anemia. Some of those in the study had to stop treatment because of the side effects.

The findings come from two studies sponsored by Vertex Pharmaceuticals Inc., which makes telaprevir. Other companies are testing similar drugs, all of which could offer hope against the disease, which affects 180 million people worldwide.

In the two studies, roughly two-thirds of patients with chronic hepatitis C given telaprevir along with standard therapy for six months showed no signs of the virus after six months - the point at which doctors consider a patient cured of the disease.

That compares with the 40 to 50 per cent who are usually cured with standard treatment alone.

In one U.S. study of 250 people, 61 per cent who took telaprevir with standard therapy for six months cleared the virus, compared with 41 per cent on standard therapy alone. Among those who took the drug and standard therapy for a year, 67 per cent had no signs of infection.

The most frequently reported side effect was a rash that caused some to discontinue the treatment, said hepatologist Dr. John McHutchison, the lead investigator on the study.

In another study of 334 people in Europe, 69 per cent on telaprevir and standard therapy for six months had undetectable virus levels compared with 46 per cent on standard treatment alone.

Results were published in Thursday's New England Journal of Medicine.

The current standard treatment for chronic hepatitis C combines the drugs peginterferon and ribavirin and is aimed at helping the immune system eliminate the virus. But less than half on it are cured.

Telaprevir and similar drugs are considered superior because they are protease inhibitors that specifically attack the hepatitis C virus.

Gastroenterologist Dr. Andrew Muir, senior investigator on the study, said they were pleased that the drug both reduced treatment time and improved cure rates.

"Either one alone would have been an advance, and to be able to achieve both is a significant step in the right direction when it comes to treating hepatitis C," he said in a news release.

Chronic hepatitis C is caused by a bloodborne virus that is spread mainly through contact with the blood of an infected person. Among other ways, it can be contracted by sharing dirty drug needles, through tattooing, or being born to an infected mother.

About a quarter of people exposed to hepatitis C clear it out of their bodies without treatment. But the rest develop a lifelong infection that can lead to liver scarring called cirrhosis, or liver cancer.