Fosamprenavir, sold under the brand names Lexiva and Telzir, is a

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

used to treat

HIV/AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ...

. It is a

prodrug A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug ...

of the protease inhibitor and

antiretroviral drug The management of HIV/AIDS normally includes the use of multiple antiretroviral drugs as a strategy to control HIV infection. There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle. The use of multiple ...

amprenavir Amprenavir (original brand name Agenerase, GlaxoSmithKline) is a protease inhibitor (pharmacology), protease inhibitor used to treat HIV infection. It was approved by the Food and Drug Administration on April 15, 1999, for twice-a-day dosing in ...

. It is marketed by

ViiV Healthcare ViiV Healthcare ( ) is a pharmaceutical company specializing in the development of therapies for HIV infection that was created as a joint venture by Pfizer and GlaxoSmithKline in November 2009 with both companies transferring their HIV assets ...

as the

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...

salt. Fosamprenavir was approved for medical use in the United States in October 2003, and in the European Union in July 2004. The human body metabolizes fosamprenavir in order to form amprenavir, which is the active ingredient. A head-to-head study with

lopinavir Lopinavir is an anti retroviral of the protease inhibitor class. It is used against HIV infections as a fixed-dose combination with another protease inhibitor, ritonavir (lopinavir/ritonavir). It was patented in 1995 and approved for medical ...

showed the two drugs to have comparable potency, but patients on fosamprenavir tended to have a higher serum cholesterol.

Medical uses

Fosamprenavir is used for the treatment of

HIV-1 The subtypes of HIV include two major types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). HIV-1 is related to viruses found in chimpanzees and gorillas living in western Africa, while HIV-2 viruses are related to viruses found in the sooty mangabey, ...

infections, typically but not necessarily in combination with low-dose

ritonavir Ritonavir, sold under the brand name Norvir, is an antiretroviral drug used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Ritonavir is a protease inhibitor a ...

or other antiviral drugs.

Adverse effects

The most common adverse effect is diarrhea. Other common side effects include

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

, dizziness and exanthema, which is usually transient. Severe allergic reactions (

Stevens–Johnson syndrome Stevens–Johnson syndrome (SJS) is a type of severe skin reaction. Together with toxic epidermal necrolysis (TEN) and Stevens–Johnson/toxic epidermal necrolysis (SJS/TEN), it forms a spectrum of disease, with SJS being less severe. Erythema ...

) are rare.

Interactions

Amprenavir (the active metabolite of fosamrenavir, which is found in blood plasma, liver and other organs) is metabolized via the liver enzyme

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs, so that they can be removed from t ...

and also weakly inhibits this enzyme. This means that combination with drugs that are also metabolized by CYP3A4 can increase their plasma concentrations and thus side effects; and combination with drugs that inhibit CYP3A4 can increase amprenavir concentrations. When combining fosamprenavir with low doses of the CYP3A4 inhibitor ritonavir, this interaction is intended as it allows for application of lower fosamprenavir doses.

Pharmacology

Fosamprenavir is quickly activated to amprenavir, even before it reaches the circulation. Amprenavir is a HIV protease inhibitor. 3nu3 478

References

External links

* * {{Portal bar , Medicine , Viruses Carbamates CYP3A4 inhibitors HIV protease inhibitors Prodrugs Sulfonamides Tetrahydrofurans