DDIs, Prescribing, Overview

Drug-drug interactions and other prescribing issues in PLWH

ARVs are recognised to be amongst the therapeutic agents with the highest potential for drug-drug interactions (DDIs) as these drugs can be both a victim (affected by other drugs) and/or a perpetrator (affect other drugs) of DDIs. Given the life-long ART, DDIs are practically unavoidable in PLWH with comorbid conditions. Thus, the potential for DDIs should be considered systematically when selecting an ART regimen or when any new medicine is coadministered to existing ART with particular attention to adjust dosage and perform clinical monitoring when needed.

The im administration of the ARVs CAB and RPV presents the advantage of eliminating DDIs occurring at the gastrointestinal level. However, DDIs can still occur at the hepatic level as illustrated below. Bypassing the gastrointestinal tract does not mitigate the magnitude of DDIs with drugs inducing metabolism.



Examples of medications interacting with the oral but not the intramuscular administration of RPV

Antacids; famotidine; lansoprazole; liraglutide; omeprazole; orlistat; pantoprazole; rabeprazole; ranitidine


Examples of medications interacting with the oral but not the intramuscular administration of CAB

Antacids; calcium; iron; magnesium; multivitamins containing divalent cations; orlistat; strontium ranelate


The DDIs profiles between ARVs and coadministered medicines within a therapeutic class are also presented in the corresponding Co-morbidities section and Viral Hepatitis Co-infection section

Detailed information on DDIs can be found on the University of Liverpool DDIs websites: http://www.hiv-druginteractions.org and http://www.hep-druginteractions.org

Age-related physiological changes and co-morbidities predispose older PLWH to inappropriate drug use or dosing in addition to DDIs

Besides highlighting the most common DDIs, this section also provides guidance on how to adjust drug dosing in case of liver or renal impairment, considerations for those with swallowing difficulties and what to consider when prescribing drugs in older PLWH including the top ten drug classes to avoid