Protease inhibitors

Protease Inhibitors 

Definition

A protease inhibitor is a type of drug that cripples the enzyme protease. An enzyme is a substance that triggers chemical reactions in the body. The human immunodeficiency virus (HIV) uses protease in the final stages of its reproduction (replication) process.

Purpose

The drug is used to treat selected patients with HIV infection. Blocking protease interferes with HIV reproduction, causing it to make copies of itself that cannot infect new cells. The drug may improve symptoms and suppress the infection but does not cure it.

Precautions

Patients should not discontinue this drug even if symptoms improve without consulting a doctor.

These drugs do not necessarily reduce the risk of transmitting HIV to others through sexual contact, so patients should avoid sexual activities or use condoms.

Description

Protease inhibitors are considered one of the most potent medications for HIV developed so far.

This class of drugs includes indinavir (Crixivan), ritonavir (Norvir), nelfinavir (Viracept), amprenavir (Agenerase), lopinavir plus ritonavir (Kaletra), saquinavir (Fortovase), and a new drug called atazanavir (Reyataz). Reyataz received approval from the U.S. Food and Drug Administration (FDA) in mid-2003 and was the first protease inhibitor approved for once-daily dosing. Several weeks or months of drug therapy may be required before the full benefits are apparent.

The drug should be taken at the same time each day. Some types should be taken with a meal to help the body absorb them. Each of the types of protease inhibitor may have to be taken in a different way. In most cases, protease inhibitors are part of a combination therapy, used in conjunction with other classes of HIV drugs.

Risks

Common side effects include diarrhea, stomach discomfort, nausea, and mouth sores. Less often, patients may experience rash, muscle pain, headache, or weakness. Rarely, there may be confusion, severe skin reaction, or seizures. Some of these drugs can have interactions with other medication, and indinavir can be associated with kidney stones. Diabetes or high blood pressure may become worse when these drugs are taken. Reyatraz has been shown to have fewer side effects than some protease inhibitors, though it can interact with other medications, including certain heart medications and antidepressants.

Experts do not know whether the drugs pass into breast milk, so breastfeeding mothers should avoid them or should stop nursing until the treatment is completed.

Resources

Periodicals

"HIV Drugs Approved as of August 2003." AIDS Treatment News July 25, 2003: 4.

LoBuono, Charlotte. "FDA Gives Bod to First Once-daily Protease Inhibitor." Drug Topics July 21, 2003: 16.

Wilson, Billie Ann. "Understanding Strategies for Treating HIV." Medical Surgical Nursing 6 (April 1, 1997): 109-111.

Organizations

National AIDS Treatment Advocacy Project. 580 Broadway, Ste. 403, New York, NY 10012. (888) 266-2827. http://www.natap.org.

Key terms

Human immunodeficiency virus (HIV) — The virus that causes AIDS.

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protease inhibitors (prōˑ·tē·ās in·hi·biˑ·terz),

n.pl a class of drugs used in antiretroviral therapy against HIV, which prevent the cleavage of viral proteins.