Chronic hepatitis C virus infection is common in the United States with an estimated prevalence of 2.7 million persons. Fortunately, the incidence of new infections has markedly declined in recent years and the natural history of chronic hepatitis usually only results in significant progression after several decades of infection. However, the majority of chronically infected patients acquired their infections more than 20 years ago; these patients with long-standing chronic hepatitis are now presenting in increasing numbers with decompensated cirrhosis and the need for liver transplantation. Cirrhosis caused by chronic hepatitis C is now the most common indication for liver transplantation. Interferon monotherapy became clinically available 10 years ago but resulted in sustained improvement in liver disease and durable loss of detectable virus in fewer than 10% of treated patients. The recent use of the combination of interferon with the nucleoside analogue ribavirin for 6-12 months results in a sustained virological response in 30%-40% of previously untreated patients. The response to this combination therapy is also excellent in patients who had initially responded to interferon monotherapy and later relapsed. Furthermore, some recent studies suggest that a small proportion of patients who failed to respond to a prior course of interferon (primarily noncirrhotic patients with low levels of virus and genotypes other than 1) may also benefit from retreatment with this combination.

Approximately 5% of the world's human population have an increased risk for developing liver cancer and cirrhosis as a direct consequence of chronic infection with the hepatitis B virus (HBV). Antiviral chemotherapy remains the only option for controlling infection in these individuals, for whom the current licensed hepatitis B vaccines provide no benefit. Interferon (IFN)-alpha has proven benefit in a well-defined group of those with hepatitis B but has made little impact on the global burden of chronic liver disease. The development of more effective chemotherapy for treatment of chronic hepatitis B infection has proven to be extremely challenging, the result of both virus- and host-dependent factors, which will be reviewed in this article. Past attempts to treat chronic hepatitis B infection using nucleoside analogues were disappointing, but more recently, several nucleoside (or nucleotide) analogues have been identified that are potent and selective inhibitors of HBV replication. These agents fall into two broad categories: (1) nucleoside/nucleotides that have modified sugar residues in either cyclic or acyclic configurations and (2) stereoisomers of nucleosides in the "unnatural" L-configuration. Of the analogues that have been used clinically, representatives of the first category are purine derivatives, e.g., adefovir dipivoxil and famciclovir, whereas representatives of the second category are pyrimidine derivatives, such as lamivudine.

In the last decade, substantial gains have been made in the treatment of inflammatory bowel disease (IBD). Refinements in drug formulation have provided the ability to target distinct sites of delivery, enhancing the safety and efficacy of older agents. Immunosuppressive agents beyond corticosteroids have assumed a routine part in the care of patients with IBD. Moreover, as the century closes, we stand at the threshold of unprecedented advances in knowledge of the pathogenesis of ulcerative colitis and Crohn's disease. Simultaneous progress in biotechnology has fostered the development of new agents that strategically target pivotal processes in disease pathogenesis. This review covers agents currently used in the treatment of IBD and seeks to provide an overview of emerging therapies.

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the committee on September 25, 1999, and by the AGA Governing Board on November 25, 1999.

This document presents the official recommendations of the American Gastroenterological Association (AGA) on intestinal ischemia. It was approved by the Clinical Practice and Practice Economics Committee on September 25, 1999, and by the AGA Governing Board on November 15, 1999.