Amprenavir is a protease inhibitor

Protease inhibitor (pharmacology)

Protease inhibitors are a class of drugs used to treat or prevent infection by viruses, including HIV and Hepatitis C. PIs prevent viral replication by inhibiting the activity of proteases, e.g.HIV-1 protease, enzymes used by the viruses to cleave nascent proteins for final assembly of new...

 used to treat HIV

HIV

Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 infection. It was approved by the Food and Drug Administration

Food and Drug Administration

The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 on April 15, 1999, for twice-a-day dosing instead of needing to be taken every eight hours. The convenient dosing came at a price, as the dose required is 1,200 mg, delivered in eight very large gel capsules.

Production of amprenavir was discontinued by the manufacturer December 31, 2004; a prodrug

Prodrug

A prodrug is a pharmacological substance administered in an inactive form. Once administered, the prodrug is metabolised in vivo into an active metabolite, a process termed bioactivation. The rationale behind the use of a prodrug is generally for absorption, distribution, metabolism, and...

 version (fosamprenavir

Fosamprenavir

Fosamprenavir , under the trade names Lexiva and Telzir is a pro-drug of the protease inhibitor and antiretroviral drug amprenavir. The FDA approved it October 20, 2003, while the EMEA approved it on July 12, 2004...

) is available.