Zidovudine and didanosine used in HAA act by:
Understanding the biology of HIV infection and availability of several potent drugs belonging to different classes has mandated &;highly active antiretroviral therapy&; (HAA) with combination of 3 or more drugs whenever indicated. Monotherapy is contraindicated. Zidovudine :It is a thymidine analogue (azidothymidine, AZT), the prototype NI. After phosphorylation in the host cell-zidovudine triphosphate selectively inhibits viral reverse transcriptase (RNA-dependent DNA polymerase) in preference to cellular DNA polymerase. Didanosine (ddl): It is a purine nucleoside analogue which after intracellular conversion to didanosine triphosphate competes with ATP for incorporation in viral DNA, inhibits HIV reverse transcriptase and terminates proviral DNA. Antiretroviral activity of didanosine is equivalent to AZT ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:770,771
Inhibitory effects on viral
DNA Nucleoside reverse transcriptase inhibition
Inhibit the synthesis of gp41
Protease inhibition
Chemotherapy