Management of Polypharmacy and Drug-Drug Interactions in HIV Patients: A 2-year Experience of a Multidisciplinary Outpatient Clinic.

HIV-positive patients are treated with various antiretroviral-containing drug combinations to control their underlying disease, which may also be combined with drugs aimed to manage independent or secondary comorbidities. This can expose patients to drug-drug interactions (DDIs) that may lead to suboptimal drug exposure, an increased risk of therapeutic failure or poor tolerability, and a need to adopt alternative therapeutic strategies. Although such undesired responses to pharmacological therapies can be appropriately managed in some situations, the fact that the available information is usually incomplete which makes it difficult (if not impossible) to assess DDIs and the consequent adjustments of polytherapies in clinical practice. For these reasons, we set up our ambulatory polytherapy management (Gestione Ambulatoriale Politerapie [GAP]) outpatient clinic in September 2016 to manage polypharmacy in HIV-infected patients. The main aims of the GAP clinic are to check whether patients are treated with drug combinations that are contraindicated due to known or predictable DDIs; assess the clinical and/or pharmacokinetic relevance of the DDIs; and provide written advice as to how the treatments should be modified if possible. We here describe the results of our 2-year experience in various clinical scenarios.