The third class of antiretroviral drugs developed against HIV were the protease inhibitors. These work far back in the life cycle of HIV, after host cell integration but before budding. These drugs affect the enzyme protease, which is used to cut up the HIV protein to be packaged into virions.

When the cell produces HIV proteins, the raw material is in a long connected string. The enzyme protease acts as a “scissor” to cut up the string into the protein for each virion. Protease inhibitors prevent protease from doing this. They resemble pieces of the protein string that protease usually cuts. This disrupts the cutting process, which prevents the chain from being cut into small pieces, which prevents HIV from making copies of itself.

Some HIV still manages to be produced, however. Fortunately, these new HIV virions are defective and non-infectious.

To find out more about the role protease plays in HIV’s life cycle, click here.

Approved Protease Inhibitors

Generic Name	Brand Name	Quantity per day	Year Approved
Saquinavir mesylate	Invirase	Nine 200mg pills	1995
Saquinavir	Fortovase	18 200mg pills	1997
Indinavir sulfate	Crixivan	6 400mg pills	1996
Ritonavir	Norvir	Twelve 100mg pills	1996
Nelfinavir mesylate	Viracept	10 250mg pills	1997
Amprenavir	Agenerase	16 150mg pills	1999
Lopinavir/ritonavir	Kaletra	Six pills	2000

Clicking on the links above will redirect your browser to the manufacturer’s product information page.

---

Sources

1. Antiretrovirals at a Glance. Chart. Princeton: Bristol-Myers Squibb Company, 2001.
2. "Drugs Used in the Treatment of HIV Infection." U.S. Food and Drug Administration. 10 Feb. 2004 <http://www.fda.gov/oashi/aids/virals.html>.
3. Gilden, Dave. "Protease Inhibitors: Overview and Analysis." Gay Men's Health Crisis April 1994. 10 Feb. 2004 <http://www.aegis.com/pubs/gmhc/1994/gm080201.html>.
4. Storad, Conrad J. Inside AIDS: HIV Attacks the Immune System. Minneapolis: Lerner Publications Company, 1998