Impact of sex, age and body composition on rilpivirine and cabotegravir trough concentrations in people with HIV receiving long-acting injectable antiretroviral therapy.

Cabotegravir trough concentrations were significantly higher in women than in men.

• Women had mean cabotegravir trough concentrations of 3285 ± 921 ng/mL versus 2096 ± 775 ng/mL in men.
• The difference was statistically significant (P < 0.001).
• The study cohort was 17% female (approximately 8 of 48 participants).
• Multivariate analysis confirmed sex as an independent predictor of cabotegravir exposure.

Cabotegravir trough concentrations were significantly higher in participants aged >65 years compared with younger individuals.

• Participants aged >65 years had mean cabotegravir trough concentrations of 2826 ± 455 ng/mL versus 2119 ± 1006 ng/mL in younger individuals.
• The difference was statistically significant (P = 0.044).
• Multivariate analysis confirmed age as an independent predictor of cabotegravir exposure.
• Mean age of the cohort was 47 ± 15 years.

Cabotegravir trough concentrations inversely correlated with skeletal muscle mass and bone mass.

• Cabotegravir levels inversely correlated with skeletal muscle mass (r = -0.45; P = 0.008).
• Cabotegravir levels inversely correlated with bone mass (r = -0.47; P = 0.006).
• Multivariate analysis confirmed muscle mass as an independent predictor of cabotegravir exposure.
• Body composition was estimated by bioelectrical impedance analysis.

Rilpivirine trough concentrations showed no significant associations with demographic or body composition variables.

• Unlike cabotegravir, rilpivirine concentrations were not significantly associated with sex, age, or body composition measures.
• Both rilpivirine and cabotegravir showed moderate intra-individual variability in trough concentrations (28–30%).
• Less than 1% of samples were below the therapeutic threshold for either drug.
• The finding was consistent across univariate and multivariate regression analyses.

Both rilpivirine and cabotegravir demonstrated moderate intra-individual variability in trough concentrations with very few samples below therapeutic thresholds.

• Intra-individual variability in trough concentrations was 28–30% for both drugs.
• Less than 1% of samples fell below the therapeutic threshold for either drug.
• The study included PWH treated with LAI rilpivirine and cabotegravir for ≥16 months with at least three consecutive plasma trough concentration assessments.
• 48 PWH were included in the analysis.

The study population consisted of 48 people with HIV receiving long-acting injectable antiretroviral therapy evaluated in a retrospective observational design.

• Mean age was 47 ± 15 years; 17% were female.
• Participants were required to have been on LAI rilpivirine and cabotegravir for ≥16 months with at least three consecutive plasma trough concentration assessments.
• Body composition was estimated by bioelectrical impedance analysis.
• Associations between drug levels and clinical variables were analysed using univariate and multivariate regression analysis.