FDA OKs New Hepatitis B Drug

Oct. 26, 2006 -- The FDA yesterday approved a new drug, called Tyzeka, to treat chronic hepatitis B in adults.

In a large clinical trial, Tyzeka was shown to be an effective antiviral agent, capable of suppressing the hepatitis B virus and improving liver inflammation comparably to Epivir-HBV, one of five medications already approved to treat chronic hepatitis B. Tyzeka is not a cure, however.

Hepatitis B is a serious viral infection that attacks the liver and can cause lifelong infection, liver scarring (cirrhosiscirrhosis), liver cancerliver cancer, liver failureliver failure, and death.

The hepatitis B virus is spread when body fluid from an infected person enters the body of an uninfected person, sometimes by sexual contact or blood contamination.

"In a typical year, an estimated 70,000 Americans become infected with chronic HBV [hepatitis B], and some 5,000 of them will die of the complications caused by the disease," says Stephen Galson, MD, MPH, and director of the FDA's Center for Drug Evaluation and Research.

"Tyzeka offers prescribers another option for treating these patients," Galson continues in an FDA news release.

About Tyzeka

Tyzeka is a new molecular entity, which is an FDA term for medication containing an active substance that has never before been approved for marketing in any form in the U.S.

Long-term benefits of Tyzeka are unknown.

Use of the drug has not been shown to reduce the risk of transmission of the hepatitis B virus to others.

Drug's Approval

Tyzeka was studied in a yearlong international clinical trial that included 1,367 patients with chronic hepatitis B. The patients were at least 16 years old; three-fourths were men.

The trial produced evidence of Tyzeka's antiviral effectiveness, including the suppression of hepatitis B virus and improvement in liver inflammation.

In clinical studies, Tyzeka was generally well tolerated. The most common side effects were elevated CPK (creatinine phosphokinase, an enzyme that marks the breakdown of muscle tissue), upper respiratory tract infection, fatiguefatigue, headache, abdominal pain, and cough.

Also, after several weeks to months of Tyzeka use, some patients developed symptoms ranging from transient muscle pain to muscle weakness.

Those who developed muscle weakness experienced significant improvement in their symptoms when Tyzeka was discontinued.

FDA's Advice

The FDA warns patients not to stop Tyzeka before a careful discussion with their doctor.

"As has happened with other forms of treatment for hepatitis B, some patients who discontinued Tyzeka experienced a sudden and severe worsening of their hepatitis B," the FDA says in the news release.

"Therefore, patients who discontinue Tyzeka should be closely monitored by their doctor for at least several months," the FDA says.

Among drugs in the same class as Tyzeka, some cases of lactic acidosis (a serious buildup of lactic acid in the body) and severe enlargement and accumulation of fat in the liver, including fatal cases, have been reported, according to the FDA.

Tyzeka is made by the drug company Novartis. Novartis is a WebMD sponsor.

SOURCE: News release, FDA.