Ribapharm Inc has begun clinical testing of the compound Hepavir B in patients with the hepatitis B virus. The Company continues to enroll patients in the Phase 1 study.

Hepavir B is a nucleoside analog that was licensed from Metabasis Therapeutics Inc., in October 2001, for development as a potential treatment for chronic hepatitis B. In August 2002, Ribapharm initiated a Phase 1 clinical trial of Hepavir B in Europe, and in October 2002 filed an Investigation New Drug (IND) application with the U.S. Food and Drug Administration (FDA) to initiate Phase 1 clinical studies in the United States.

Phase 1 clinical trials usually involve between 20 and 80 healthy volunteers or patients and typically take one to two years to complete. Phase 1 tests a drug's safety profile and may seek to establish the safe dosage range. The tests also determine how a drug candidate is absorbed, distributed, metabolized and excreted from the body. Ribapharm's testing of Hepavir B in Phase 1 is a multiple rising dosage study.

Hepatitis B is a viral infection of the liver caused by the hepatitis B virus, or HBV. The World Health Organization (WHO) estimates that more than 400 million people worldwide are chronically infected with HBV.