Objectives: The aim of the research was to determine prevalence of potential drug interactions among elderly patients in the Shahid Bahonar ICU in Kerman.

Methods & Materials: In this cross sectional study, data about all elderly patients who were admitted in the intensive care unit from 1/4/2009 to 1/4/2010 were retrieved from medical records and evaluated with regard to the number and type of drug interactions, the number of drugs administered, age, sex, length of stay in the ICU, and the number of doctors prescribing medications of medications administered. The extent and number of drug interactions were investigated based on the reference textbook Drug Interaction Facts and in order to analyze the data collected, using SPSS 18 and according to study goals, a descriptive test, Pierson's correlation test, an independent T-test and a one-way ANOVA were used.

Results: In total, 77 types of drugs and 394 drugs were prescribed with a mean of 5.6(SD=1.5) drugs per patient. A total of 108 potential drug interactions were found related to drugs prescribed during the first twenty-four hours. In terms of the type of drug interactions, delayed, moderate and possible types comprised the highest proportion of drug interactions. The four major interactions were between cimetidine and methadone, furosemide and amikacine, phenytoin and dopamine, and heparin and aspirin. The results of Pierson's correlation test were inicative of a positive correlation between the number of potential drug interactions and that of the drugs prescribed (r=0.563, P<0.05). Results of a one-way ANOVA showed that the mean number of potential drug interaction were significantly higher in those who died than in other patients (P<0.05).

Conclusion: Elderly patients who are admitted to the intensive care unit are at a high risk of developing drug interactions and better care must be taken by medical team members.