protease inhibitors

Protease Inhibitors



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.


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.


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.


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.


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.



"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.


National AIDS Treatment Advocacy Project. 580 Broadway, Ste. 403, New York, NY 10012. (888) 266-2827.

Key terms

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

protease inhibitors

A range of drugs that interfere with the action of the enzyme protease used by HIV to activate the synthesis of its capsid by processing the viral GAG protein. These drugs slow the progression of the infection and lengthen life. An undesirable direct or indirect effect is the abnormal laying-down of body fat and high levels of lipids in the blood, which may lead to coronary artery disease and strokes. Brand names are indinavir, ritonavir and saquinavir.

protease inhibitors (prōˑ·tē·ās in·hi·biˑ·terz), a class of drugs used in antiretroviral therapy against HIV, which prevent the cleavage of viral proteins.
References in periodicals archive ?
For these patients, the decision to change the prescribed protease inhibitor to indinavir and to prescribe rifabutin for TB therapy should be made in consultation with an expert in the use of protease inhibitors to manage HIV infection.
WASHINGTON - Protease inhibitors, a new class of antiviral drugs being developed by major pharmaceutical manufacturers, are being hailed as a major step forward in the battle to control AIDS.
On the other hand, HIV resistant to one protease inhibitor may not be resistant to all other protease inhibitors.
The trial was stopped because some of these volunteers had a poor antiviral response to TMC125; those in the control group, who were treated with protease inhibitors instead, did better in reducing viral load.
The new drug, called TMC114 by maker Tibotec of Mechelen, Belgium, belongs to a class of agents known as protease inhibitors, which are commonly prescribed to control HIV but often lose effectiveness over time.
The four new anti-HIV drugs that came out in 2003 are Fuzeon, part of a new class of drugs called entry inhibitors or fusion inhibitors; the protease inhibitors Reyataz and Lexiva; and the reverse transcriptase inhibitor Emtriva.
Patients on protease inhibitors should not exceed a 25-mg sildenafil dose every 48 hours," said Dr.
SAN FRANCISCO -- Protease inhibitors can cause more than a 10-fold increase in sildenafil levels, which can lead to unpleasant side effects in patients taking both drugs, Ian R.
The relevance of resistance to other protease inhibitors (PIs) on the virologic success of Kaletra has not yet been fully characterized.
The Food and Drug Administration approved the first three protease inhibitors, members of a new class of antiretrovirals that may be considered-the most potent therapeutic agents for HIV to date.