Antiretroviral treatment is the mainstay in HIV treatment. The goals of antiretroviral therapy are to inhibit replication of HIV and to reduce morbidity and death.
The anti-HIV drugs can be broadly classified as: (a) nucleoside analog reverse transcriptase inhibitors (NRTIs), (b) non-nucleoside reverse transcriptase inhibitors (NNRTIs), or (c) protease inhibitors.
Nucleoside analog reverse transcriptase inhibitors (NRTIs): Azidothymidine (AZT), didanosine (DDI), and othernucleoside analogs inhibit the enzyme reverse transcriptase and alter their incorporation into DNA to cause chain termination. These agents prevent the spread of the virus to uninfected cells.
AZT is recommended for treatment of asymptomatic or mildly symptomatic people with CD4 count of less than 500/ L. This is also recommended for treatment of pregnant women to reduce the possibility of transmission of the virus to the fetus. The toxicity associated with high doses of AZT and the emergence of resistance to AZT is the main disadvantage of monotherapy with AZT. Zidovudine is also used effectively to reduce significant transmission of HIV from mother to infant. The treatment decreases vertical transmission at all levels of maternal viral load.
Non-nucleoside reverse transcriptase inhibitors (NNRTIs):
NNRTIs, such as nevirapine, delaviridine, and efavirenz, inhibit the enzyme by blocking the morphogenesis of the virion by inhibiting the cleavage of the Gag and Gag core polyproteins. This in turn prevents activation of the virion.
Protease inhibitors: Protease inhibitors, such as ritonavir,indinavir, saquinavir, nelfinavir, and amprenavir, prevent the maturation of viral particle during late stage of viral replication. Monotherapy with antiretroviral therapy failed to produce significant clinical benefits including survival of the patient. The failure is partly due to the development of drug-resistant variants of HIV because resistance develops rapidly during monotherapy and cross-resistance between related drugs is also being increasingly reported.
Multidrug therapy reduces morbidity due to the disease and death in many patients due to AIDS is delayed.