title: Drug-drug interactions and their predictors: Results from Indian elderly inpatients.
abstract: BACKGROUND
  In view of the multiple co-morbidities, the elderly patients receiving drugs are prone to suffer with drug interactions since they receive a greater number of drugs.
  
  
  OBJECTIVE
  The study was undertaken to determine the prevalence of drug interactions, as well as their predictors.
  
  
  METHODS
  The prescriptions of a total of 1510 inpatients were collected prospectively for 1.5 years from inpatients wards of public tertiary care teaching hospital. All the prescriptions were checked for drug interactions using the Micromedex® Drug-Reax database-2010 and Stockley's Drug Interactions. Regression analyses sought to determine predictors for the drug interaction.
  
  
  RESULTS
  The patients, with the average age of 67.2 ±0.2 years, were prescribed an average of 9.15 ±0.03 medications. It was found that out of 1510 prescriptions of inpatients, 126 (8.3%) prescriptions had one or more than one drug interaction. All the identified interactions were severe in nature. The top most interacting drugs were acetylsalicylic acid and anticoagulant (n=59). The second top most interacting drug combination was clopidogrel and proton pump inhibitors (n=51). The most commonly involved drugs in interactions were C (cardiovascular system) and A (alimentary tract and metabolism). Using multivariate binary logistic regression, multiple drugs (Odds Ratio=4.5; 95% Confidence Interval: - 2.38 -9.47) and multiple diagnoses (Odds Ratio=2.6; 95%CI: -1.40 -5.57) were found to be significant predictors for drug interaction.
  
  
  CONCLUSIONS
  The results of this study substantiate the occurrence of severe drug interactions among Indian elderly inpatients. In order to provide safer pharmaceutical care, the active involvement of clinical pharmacists is a potential option.
authors.affiliation: Research Centre, Montreal University . Montreal ( Canada ). avi_mandu@yahoo.co.in.
authors.forename: Mandavi
authors.initials: M
authors.lastname: Kashyap
authors.affiliation: Department of General Medicine, Government Medical College & Hospital. Chandigarh ( India ).
authors.forename: Sanjay
authors.initials: S
authors.lastname: D'Cruz
authors.affiliation: Department of General Medicine, Director Principal, Government Medical College & Hospital. Chandigarh ( India ).
authors.forename: Atul
authors.initials: A
authors.lastname: Sachdev
authors.affiliation: Department of Pharmacy Practice. National Institute of Pharmaceutical Education and Research, S.A.S. Nagar ( India ).
authors.forename: Pramil
authors.initials: P
authors.lastname: Tiwari
keywords: Drug Interactions; India; Inpatients