The active ingredients of Combivir are lamivudine and zidovudine. Both these belong in non-the nucleoside reverse transcriptase inhibitor (NRTI) class of antiretroviral drugs.
The two ingredients have been shown to act synergistically against HIV.
HIV is a retrovirus: it holds all its genetic information in the form of RNA. When it infects a host cell, the RNA gets copied into DNA by an enzyme called reverse transcriptase. In the form of DNA, the viral genetic code can integrate itself into its hostís own DNA. Then, as the hostís DNA is copied into RNA and then proteins are produced according to the code, the viral DNA gets copied along, and produces its own proteins. The viral proteins together with viral RNA then join to make up more viruses. Lamivudine and zidovudine both work by inhibiting the action of reverse transcriptase, thus inhibiting the propagation of HIV.
Coadministration of lamivudine and zidovudine was shown to decrease the levels of HIV RNA in the body, and to increase the levels of CD4+ cells (cells of our immune system and one of the main targets of HIV Ė their levels normally decrease after an HIV infection).