Abstract

One of the greatest challenges for the HIV clinician is the recognition and management of drug interactions. The HIV infected patient often receives numerous medications and has a great potential for adverse drug interactions. Although many of these interactions may be minor in nature, some are potentially serious, leading to severe toxicity or treatment failure. The aim of this study is to determine the incidence, pattern and to identify risk factors for possible drug-drug interactions (DDIs) in human immunodeficiency virus positive patients with antiretrovirals (ARVs) in an Indian tertiary care teaching hospital. A prospective case control study was performed for monitoring drug-drug interactions to antiretroviral therapy during hospitalization from August 2009 to March 2010. Possible DDIs found were classified according to Tatro. The prescription of each enrolled patient during hospitalization was reviewed and analyzed by a graduate trainee clinical pharmacist for possible drug to drug interactions based on Online Stockley’s Drug Interactions (9^th edition), Micromedex Online Drug Reference and Martindale, The Complete Drug Reference. The possible DDIs found were classified according to a clinical significance rating expressed as a number assigned to each DDI based on onset, severity and documentation. Multivariate logistic regressions were used to identify the risk factors for DDIs. The data consisted of 118 hospitalized HIV patients with ARV prescriptions. Out of which 175 DDIs were detected involving 77 patients. The overall incidence rate of DDIs was 65.2% and pharmacokinetic DDIs was the most commonly observed DDIs. ‘Minor’ and ‘moderate’ drug-drug interactions accounted for 50.8 and 26.9% respectively. A maximum of six DDIs was reported from a single patient. Most of the patients who developed DDIs were receiving more than nine to eleven drugs at the time of experiencing DDIs. Polypharmacy, tuberculosis and syphilis were observed as risk factors for DDIs. The increase in use of newer antiretrovirals in India increases the risk for drug interactions and complicates their management on HIV/AIDS. It is therefore recommended that clinicians must focus to detect potential DDIs at time of prescription of ARVs to ensure better patient care.

Key words: Drug interactions, antiretroviral therapy, highly active, India.