<prompt> Nucleoside reverse transcriptase inhibiting drug, which is a guanosine analogue: March 2012RitonavirZidovudineAbacavirAcyclovir  <response>: Ans: C i.e. Abacavir Anti-viral drugs and mechanism of action Ritonavir is a potent retroviral protease inhibitor Zidovudine is a thymidine analogue, the prototype of nucleoside reverse transcriptase inhibitors NI Abacavir, a guanosine analogue nucleoside reverse transcriptase inhibitors, is a potent ARV drug that acts after intracellular conversion to carbovir triphosphate. Acyclovir is a deoxiguanosine analogue antiviral drug anti-herpes, which requires a virus specific enzyme for conversion to the active metabolite that inhibits DNA synthesis and viral replication 