Absence of Pharmacodynamic Interference Following Concomitant Administration of Long-Acting Cabotegravir/Rilpivirine and Intramuscular Antibiotics for Sexually Transmitted Infections in People with HIV

Background: Long-acting cabotegravir/rilpivirine (CARLA) is an effective treatment for HIV-1. However, concerns remain regarding potential pharmacodynamic interactions, particularly with intramuscular antibiotics used to treat sexually transmitted infections (STIs), which are common among people living with HIV (PLWH). Objective: The objective of this study was to assess whether concomitant intramuscular administration of CARLA and antibiotics affects antiretroviral control or impairs the syphilis serological response. Methods: A retrospective, monocentric cohort study was conducted. The first analysis compared PLWH receiving CARLA and intramuscular antibiotics (benzathine penicillin, ceftriaxone, or gentamicin) with those receiving only CARLA. HIV RNA levels were evaluated before and after injection. The second analysis evaluated the serological response to syphilis treatment in PLWH who received CARLA versus controls not treated with CARLA. Serological response was defined as a fourfold decrease in the rapid plasma reagin (RPR) titer. Statistical comparisons included non-parametric tests and Cox regression analysis. Results: Among the 201 individuals included in the antiretroviral response analysis, no significant differences in HIV RNA suppression or blips were observed between the groups. Similarly, in 303 individuals assessed for syphilis response, the serological response rate and time to response were comparable. Adjusted Cox regression did not show an association between CARLA co-administration and delayed serological response (aHR 0.9, 95% CI 0.52–1.58, p=0.723). Discussion: Concomitant intramuscular administration of CARLA and antibiotics does not appear to compromise HIV viral suppression or syphilis serological response. Conclusion: These findings support the co-administration of long-acting antiretrovirals and intramuscular antibiotics without compromising their effectiveness.