Bictegravir is a component of a single-tablet HIV regimen (B/F/TAF). As an integrase strand transfer inhibitor (INSTI), its advantage over first-generation INSTIs (raltegravir, elvitegravir) includes:

• A Bictegravir inhibits both integrase catalytic activity and HIV capsid protein, providing dual-mechanism activity
• B Bictegravir has a higher genetic barrier to resistance — key resistance mutations (Q148H/R, N155H) that confer raltegravir/elvitegravir resistance have minimal impact on bictegravir efficacy ✓
• C Bictegravir is a pharmacokinetic booster that does not require ritonavir or cobicistat
• D Bictegravir acts on both integration and reverse transcription steps of the HIV lifecycle

Explanation

First-generation INSTIs raltegravir and elvitegravir have a low genetic barrier to resistance: single mutations like N155H or Q148H/R significantly reduce their activity. Bictegravir (a second-generation INSTI, along with dolutegravir and cabotegravir) has bulkier contact interactions with the integrase active site, meaning single mutations have little effect on bictegravir binding — a higher genetic barrier to resistance. This makes bictegravir less likely to fail virologically in adherent patients. Option C describes dolutegravir and bictegravir not needing a pharmacokinetic booster (unlike elvitegravir, which needs cobicistat), which is also true but not the primary stated advantage.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.