What is amprenavir, and how does it work (mechanism of action)?
This drug was discontinued as of October of 2007.
Amprenavir is an oral medication that is used for treating infections with the human immunodeficiency virus (HIV). It is in a class of drugs called protease inhibitors which, among others, includes indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir) and saquinavir (Invirase, Fortovase). During infection with HIV, the HIV virus multiplies within the body's cells. Viruses are released from the cells and spread throughout the body where they infect other cells. In this manner, HIV infection is perpetuated among new cells that the body produces continually. During the production of the viruses, new proteins are made. Some of the proteins are structural proteins, that, is, proteins that form the body of the virus. Other proteins are enzymes which manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. Amprenavir blocks the activity of protease and results in the formation of defective viruses that are unable to infect the body's cells. As a result, the number of viruses in the body (the viral load) decreases. Nevertheless, amprenavir does not prevent the transmission of HIV among individuals, and it does not cure HIV infections or AIDS. Amprenavir was approved by the FDA in April 1999.
What are the side effects of amprenavir?
The most frequent side effects are headache, weakness, diarrhea, nausea and stomach pain. Amprenavir may also cause severe skin reactions and breakdown of red blood cells. The propylene glycol in the oral solution can cause seizures, stupor, increased heart rate, metabolic disturbance, and kidney failure. Like other protease inhibitors, use of amprenavir may be associated with redistribution or accumulation of body fat, increased cholesterol and worsening of diabetes.
What is the dosage for amprenavir?
The recommended dose is based on age, weight and the formulation. Individuals 4-12 years old or 13-16 years old and weighing less than 50 kg should receive 22.5 mg/kg twice daily or 17 mg/kg three times daily of the oral solution or 20 mg/kg twice daily or 15 mg/kg three times daily of the capsules.
Individuals 13- 16 years old who weigh 50 kg or more and individuals older than 16 years of age should receive 1400 mg twice daily of the oral solution or 1200 mg twice daily of the capsules.
The maximum daily dose is 2800 mg. Amprenavir capsules and solution are not interchangeable milligram for milligram. The oral solution should only be used when it is not possible to administer the capsules.
Amprenavir can be taken with or without food. However, foods high in fat may decrease the absorption of amprenavir and should be avoided.
Is amprenavir safe to take if I'm pregnant or breastfeeding?
It is not known whether amprenavir is secreted in breast milk. Nevertheless, HIV-infected mothers should not breast-feed because of the potential risk of transmitting HIV to an infant that is not infected.
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