Which of the following is an INSTI?

• A. Efavirenz
• B. Lopinavir
• C. Bictegravir
• D. Zidovudine

Answer: (C)

Identifying the drug class by mechanism of action. An integrase strand transfer inhibitor blocks the HIV enzyme integrase, preventing viral DNA from integrating into the host genome and thereby stopping replication early in the cycle. Bictegravir is an integrase strand transfer inhibitor and is used in modern regimens (often combined with emtricitabine and tenofovir alafenamide as a single-tablet therapy). In contrast, efavirenz is an NNRTI (it inhibits reverse transcriptase), lopinavir is a protease inhibitor (it prevents virion maturation), and zidovudine is an NRTI (it also inhibits reverse transcriptase via chain termination). So the drug that belongs to the INSTI class is Bictegravir.