Zidovudine is classified as which type of antiviral agent?

• A. Protease inhibitor
• B. Reverse Transcriptase inhibitor
• C. Fusion inhibitor
• D. Integrase inhibitor

Answer: (B)

Zidovudine blocks the step where HIV converts its RNA into DNA, so it is a nucleoside reverse transcriptase inhibitor (NRTI). As a nucleoside analogue, it must be phosphorylated inside the cell to the active triphosphate form and then competes with the natural deoxynucleotides for incorporation by reverse transcriptase. Once incorporated, it lacks a 3'-OH group, causing chain termination of the viral DNA strand and halting replication. It is not a protease inhibitor (which would disrupt viral protein processing), a fusion inhibitor (which blocks entry), or an integrase inhibitor (which prevents integration of viral DNA into the host genome).