What is the primary mechanism of action of Zidovudine?

What is the primary mechanism of action of Zidovudine?

• A. Inhibits Reverse Transcriptase
• B. Inhibits DNA polymerase
• C. Inhibits protease
• D. Inhibits integrase

Answer: (A)

Zidovudine is a nucleoside reverse transcriptase inhibitor. It enters cells and is phosphorylated to the active triphosphate form, then competes with the natural nucleotide for incorporation by HIV reverse transcriptase. Once Zidovudine is incorporated into the viral DNA, it lacks a 3’-hydroxyl group, so DNA chain elongation cannot continue. This premature termination of the viral DNA synthesis prevents replication of the virus. Other drug classes target different steps—protease inhibitors block processing of viral proteins, integrase inhibitors prevent integration of viral DNA into the host genome, and broad DNA polymerase inhibition would affect host enzymes rather than specifically blocking HIV replication. The essence is that Zidovudine stops reverse transcription by acting as a chain-terminating nucleoside analogue.

Zidovudine is a nucleoside reverse transcriptase inhibitor. It enters cells and is phosphorylated to the active triphosphate form, then competes with the natural nucleotide for incorporation by HIV reverse transcriptase. Once Zidovudine is incorporated into the viral DNA, it lacks a 3’-hydroxyl group, so DNA chain elongation cannot continue. This premature termination of the viral DNA synthesis prevents replication of the virus. Other drug classes target different steps—protease inhibitors block processing of viral proteins, integrase inhibitors prevent integration of viral DNA into the host genome, and broad DNA polymerase inhibition would affect host enzymes rather than specifically blocking HIV replication. The essence is that Zidovudine stops reverse transcription by acting as a chain-terminating nucleoside analogue.