Background Antiretroviral therapy has transformed HIV infection from a deadly into a chronic condition. Aging people with HIV (PWH) are at higher risk of polypharmacy, potential drug–drug interactions (DDIs), and potentially inappropriate medications (PIMs). This study aims to compare prescribed drugs, polypharmacy, and potential DDIs between young (<65 years old) and elderly (≥65 years old) PWH. The prevalence of PIMs was assessed in elderly. Methods PWH from 2 centers within the Swiss HIV Cohort Study were asked to fill in a form with all their current medications. Polypharmacy was defined as being on ≥5 non-HIV drugs. PIMs were evaluated using Beers criteria. Potential DDIs for the most prescribed therapeutic classes were screened with the Liverpool interaction database. Results Among the 996 PWH included, 122 were ≥65 years old. Polypharmacy was more frequent in the elderly group (44% vs 12%). Medications and potential DDIs differed according to the age group: cardiovascular drugs and related potential DDIs were more common in the elderly group (73% of forms included ≥1 cardiovascular drug; 11% of cardiovascular drugs involved potential DDIs), whereas central nervous system drugs were more prescribed and involved in potential DDIs in younger PWH (26%, 11%). Potential DDIs were mostly managed through dosage adjustments. PIMs were found in 31% of the elderly group. Conclusions Potential DDIs remain common, and PIMs constitute an additional burden for the elderly. It is important that prescribers develop and maintain a proactive approach for the recognition and management of DDIs and other prescribing issues frequently encountered in geriatric medicine.

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Aims The aims of this study were to characterize escitalopram pharmacokinetic profile, to identify factors influencing drug exposure, notably drug–drug interactions with antiretrovirals, and to simulate expected exposure under standard dosage regimen. Methods A population pharmacokinetic analysis was performed using NONMEM. A total of 159 plasma concentration measurements were obtained from 39 human immunodeficiency virus (HIV)‐infected and 71 uninfected psychiatric patients. The influence of age, weight, sex, HIV and psychiatric cohorts, racemic citalopram treatment, and comedications on oral clearance was examined. Simulations served to calculate the percentage of patients expected to be under‐ or over‐exposed, considering established therapeutic targets (15–80 ng/mL). Results A 1‐compartment model with first‐order absorption and elimination described the data adequately. The average escitalopram clearance and volume of distribution were 23.1 L/h (interindividual variability 51%), and 920 L, respectively. Escitalopram disposition did not differ between HIV‐infected and uninfected patients, and was not affected by antiretroviral treatments. Coadministration of at least 1 proton‐pump inhibitor (CYP2C19 inhibitor) modestly influenced escitalopram elimination (clearance decreased by 19%), with limited clinical relevance. Model‐based simulations showed that, under a standard regimen of 10 mg once daily, a significant proportion of patients (56%) might be under‐exposed. Conclusion The variability in escitalopram disposition is large and poorly explained by demographic, clinical and environmental covariates, thus suggesting a role for dosage individualization based on therapeutic drug monitoring in case of poor clinical response. Escitalopram disposition is modestly impacted by comedications and therefore no a priori dosage adjustments are needed in patients receiving antiretroviral treatments, including boosted regimens.

The widespread use of highly active antiretroviral treatments has dramatically changed the prognosis of people living with HIV (PLWH). However, such treatments have to be taken lifelong raising issues regarding the maintenance of both therapeutic effectiveness and long-term tolerability. Recently approved or investigational antiretroviral drugs present considerable advantages, allowing once daily oral dosage along with activity against resistant variants (eg, bictegravir and doravirine) and also parenteral intramuscular administration that facilitates treatment adherence (eg, long-acting injectable formulations such as cabotegravir and rilpivirine). Still, there remains a risk of insufficient or exaggerated circulating exposure due to absorption issues, abnormal elimination, drugdrug interactions, and others. In this context, a multiplex ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) bioassay has been developed for the monitoring of plasma levels of bictegravir, cabotegravir, doravirine, and rilpivirine in PLWH. A simple and convenient protein precipitation was performed followed by direct injection of the supernatant into the UHPLC-MS/MS system.The four analytes were eluted in less than 3 minutes using a reversed-phase chromatography method coupled with triple quadrupole mass spectrometry detection. This bioassay was fully validated following international guidelines and achieved good performances in terms of trueness (94.7%-107.5%), repeatability (2.6%-11%), and intermediate precision (3.0%-11.2%) over the clinically relevant concentration ranges (from 30 to 9000 ng/mL for bictegravir, cabotegravir, and doravirine and from 10 to 1800 ng/mL for rilpivirine). This sensitive, accurate, and rapid UHPLC-MS/MS assay is currently applied in our laboratory for routine therapeutic drug monitoring of the oral drugs bictegravir and doravirine and is also intended to be applied for the monitoring of