as salt: InChI=1S/C25H36N3O9PS.Ca/c1-18(2)15-28(39(33,34)22-10-8-20(26)9-11-22)16-24(37-38(30,31)32)23(14-19-6-4-3-5-7-19)27-25(29)36-21-12-13-35-17-21;/h3-11,18,21,23-24H,12-17,26H2,1-2H3,(H,27,29)(H2,30,31,32);/q;+2/p-2/t21-,23-,24+;/m0./s1
Fosamprenavir was approved for medical use in the United States in October 2003,[6] and in the European Union in July 2004.[4] The human body metabolizes fosamprenavir in order to form amprenavir, which is the active ingredient.[3]
A head-to-head study with
lopinavir showed the two drugs to have comparable potency, but patients on fosamprenavir tended to have a higher serum cholesterol.[7]
Medical uses
Fosamprenavir is used for the treatment of
HIV-1 infections, typically but not necessarily in combination with low-dose
ritonavir or other antiviral drugs.[8][9]
Adverse effects
The most common adverse effect is diarrhea. Other common side effects include
headache, dizziness and exanthema, which is usually transient. Severe allergic reactions (
Stevens–Johnson syndrome) are rare.[8]
Interactions
Amprenavir (the active metabolite of fosamrenavir, which is found in blood plasma, liver and other organs) is metabolized via the liver enzyme
CYP3A4 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.[8]
When combining fosamprenavir with low doses of the CYP3A4 inhibitor ritonavir, this interaction is intended as it allows for application of lower fosamprenavir doses.[8]
Pharmacology
Fosamprenavir is quickly activated to amprenavir, even before it reaches the circulation. Amprenavir is a HIV
protease inhibitor.[8]
^Eron J, Yeni P, Gathe J, Estrada V, DeJesus E, Staszewski S, et al. (August 2006). "The KLEAN study of fosamprenavir-ritonavir versus lopinavir-ritonavir, each in combination with abacavir-lamivudine, for initial treatment of HIV infection over 48 weeks: a randomised non-inferiority trial". Lancet. 368 (9534): 476–82.
doi:
10.1016/S0140-6736(06)69155-1.
PMID16890834.
S2CID33612672.
^
abcdeJasek W, ed. (2007). Austria-Codex (in German) (62nd ed.). Vienna: Österreichischer Apothekerverlag. pp. 8009–17.
ISBN978-3-85200-181-4.