INSTIbased

INSTI-based regimens are antiretroviral therapies that center on an integrase strand transfer inhibitor (INSTI) to treat HIV-1 infection. INSTIs block the integration of viral DNA into the host genome, preventing replication. The main INSTIs are dolutegravir, bictegravir, raltegravir and elvitegravir. Most regimens combine an INSTI with two NRTIs, and several are available as single-tablet formulations (for example, dolutegravir/emtricitabine/tenofovir alafenamide and bictegravir/emtricitabine/tenofovir alafenamide).

Efficacy: In trials and real-world use, INSTI-based regimens achieve virologic suppression comparable to other first-line regimens in ART-naive patients and in those switching therapy. They often offer favorable tolerability and simplified dosing, which supports adherence.

Safety and interactions: Generally well tolerated; common adverse effects include headache and fatigue. Some agents have been linked to weight gain or mood changes. Interactions exist with polyvalent cations, requiring dosing separation; rifampin or enzyme inducers may necessitate regimen adjustments.

Resistance and monitoring: Dolutegravir and bictegravir have relatively high genetic barriers to resistance; raltegravir and elvitegravir can develop resistance more readily. Cross-resistance within the class is possible. Baseline resistance testing and regular HIV RNA monitoring remain standard.

Guidelines and use: INSTI-based regimens are widely recommended as first-line therapy in many guidelines. Choice depends on HBV coinfection, pregnancy planning, prior resistance, and potential drug interactions. Availability as single-tablet regimens supports adherence and access in many populations.