Therapy of acute and chronic viral hepatitis.

Viral hepatitis comprises five different diseases caused by five different viral agents: hepatitis A, B, C, D, and E virus. All five forms can cause acute hepatitis, only hepatitis B, C and D can cause chronic hepatitis. Alpha interferon has been shown to be effective in inducing sustained remissions in all three forms of chronic viral hepatitis. Its efficacy in acute viral hepatitis has not been documented, although preliminary results suggest that interferon may decrease the chronicity rate of acute hepatitis C. In chronic hepatitis B, alpha interferon therapy with 5 mu daily or 10 mu three time weekly for 16 weeks will induce a long-term remission in disease with loss of HBV DNA and HBeAg from serum in 25% to 40% of patients and ultimately, a loss of HBsAg in approximately half of the responders. Patients likely to respond are those with high initial serum aminotransferases and low levels of HBV DNA. In chronic hepatitis C, therapy with 3 to 5 mu of alpha interferon 3 times weekly for 24 to 48 weeks will induce a temporary remission in disease with loss of HCV RNA from serum, fall of aminotransferases into the normal range and improvement in liver histology in 50% of patients and a sustained remission persisting after therapy is stopped in 25% of patients. Patients with a short duration of disease and without cirrhosis are the most likely to respond. Unfortunately, there are no completely reliable means of predicting which patients are likely to respond to interferon and which of these will have a lasting response. In chronic hepatitis D, a prolonged course of alpha interferon given in doses of 3 to 5 mu daily or 9 to 10 mu three times weekly results in remission in disease as marked by loss of HDV RNA from blood and fall of aminotransferases into the normal range in up to 50% of patients. Unfortunately, this response is rarely sustained after treatment unless HBsAg becomes negative, which occurs in only a small number of patients. Despite the benefits of alpha interferon therapy in many patients with chronic viral hepatitis, several shortcomings of this therapy are evident: less than 50% of patients respond, side effects can be problematical, and some patients are not appropriate for therapy. Thus, interferon is not indicated for patients with advanced cirrhosis or for those who are severely immunosuppressed. Alpha interferon is an important first step in therapy for chronic viral hepatitis, but further approaches are needed to increase its efficacy and safety.