Antiviral therapy of chronic hepatitis B: past, present, and future.

A wide variety of agents has been used to treat chronic hepatitis B, but none has proved effective with the exception of interferon. Toxicity has been a major problem with some drugs whereas in others a lack of antiviral potency has been demonstrated. Alpha-interferon represents a good compromise because it has both immunomodulatory and antiviral properties; moreover, it is generally well tolerated. Loss of HBeAg and hepatitis B virus DNA may be anticipated in 40-50% of patients who are treated with doses of 5 million units daily or 10 million units thrice weekly for 16 weeks. While drug-related adverse effects occur commonly, the majority of clinically stable patients are able to tolerate this regimen, and withdrawal from drug is necessary in approximately 5% of patients. Unlike the situation with chronic hepatitis C, loss of viral replication tends to be sustained years later. Disappearance of HBsAg only occurs in 10-15% of treated patients within the first year after therapy, but an increasing number of responders demonstrate HBsAg seroconversion upon prolonged follow-up. Hepatitis B virus DNA usually disappears from serum by polymerase chain reaction at the time of HBsAg loss. Low copy numbers of residual viral DNA are still detectable in liver tissue at this time, but this has uncertain significance. Marked improvement in histological features has been observed years after loss of HBsAg. Pre-therapy levels of circulating viral DNA and aminotransferase activity, degree of histologic activity, and HIV status appear to influence the response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)