adefovir dipivoxil + abacavir + efavirenz + amprenavir

This is a **combination drug consisting of adefovir dipivoxil, abacavir, efavirenz, and amprenavir**, each of which is an antiviral agent used primarily in the treatment of HIV infection (though adefovir dipivoxil is primarily approved for hepatitis B). - **Adefovir dipivoxil** is a nucleotide analog reverse transcriptase inhibitor (ntRTI); it is a prodrug that is rapidly converted to adefovir, inhibiting viral polymerase and causing chain termination in HBV and with in vitro activity against HIV[2][1]. - **Abacavir** is a nucleoside reverse transcriptase inhibitor (NRTI), active against HIV-1 as it gets incorporated into viral DNA, causing termination. - **Efavirenz** is a non-nucleoside reverse transcriptase inhibitor (NNRTI), directly inhibiting HIV-1 reverse transcriptase by binding to a hydrophobic pocket on the enzyme. - **Amprenavir** is a protease inhibitor, which disrupts the viral protease enzyme required to process HIV polyproteins, thereby preventing maturation of infectious virions. No record of a commercial fixed-dose combination product containing all four agents was found.