Nokea
Which of the following drug which directly inhibits HIV-reverse transcriptase * without the need for intracellular activation by phosphorylation:
Correct Answer: B
Rationale: The correct answer is B: Nevirapine. Nevirapine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that directly inhibits HIV-reverse transcriptase without needing intracellular activation. It binds directly to the enzyme's active site, preventing the conversion of viral RNA to DNA.
Rationale:
1. Nelnavir (A) is a protease inhibitor that works by blocking the protease enzyme needed for viral replication, not reverse transcriptase inhibition.
2. Stavudine (C) and Didanosine (D) are nucleoside reverse transcriptase inhibitors (NRTIs) that require intracellular phosphorylation to become active, unlike Nevirapine.
In summary, Nevirapine is the correct answer as it directly inhibits HIV-reverse transcriptase without needing intracellular activation, distinguishing it from the other choices which belong to different drug classes or require intracellular phosphorylation.