Fosamprenavir Calcium (Amprenavir
phosphate; GW-433908) is a phosphate ester prodrug of Amprenavir with
improved solubility. It can be used as an anti-HIV drug. Amprenavir
(formerly VX-478; trade name Agenerase and Prozei), an FDA approved drug
for treating HIV infections, is a potent PXR-selective agonist, and an
HIV protease inhibitor with the IC50 of 0.6 nM on HIV-1 protease,
it also weakly inhibits HIV-2 protease with IC50 value of 19 nM. In
addition, it is reported to be a Cytochrome P450 3A4 Inhibitor.
Amprenavir has been effectively used for the treatment of HIV disease in
patients with primary HIV infection. It was approved by the FDA on
April 15, 1999, for twice-a-day dosing instead of needing to be taken
every eight hours.