Study of Drug-Drug Interactions in Prescriptions of General Practitioners and Specialists in Iran 2007-2009

Prescriptions written by general practitioners and medical specialists were studied and compared to determine the type, time of onset and clinical importance of drug-drug interactions (DDIs) in an attempt to reduce further complications. In 2007, 28, 956, 638 prescriptions and 15, 610, 912 prescriptions in 2008 were filled by pharmacies affiliated with medical science universities. These prescriptions, prescribed by physicians from 33 Iranian medical universities nationwide were then evaluated with a prescription processing software named Pardazesh Nosakh. After processing and analyzing the data, DDIs were discovered in 14 different medical specialists consisting of internists, cardiologists, neurologists, psychiatrists, neurosurgeons, general surgeons, infectious diseases, urologists, dermatologists, ENT, ophthalmologists, orthopedists, and pediatrician. The results were then analyzed through methods applied in the book of Drug Interaction Facts. The results revealed that in 2007-2008, 0.77% of prescriptions had DDIs out of which 0.67% were with significant clinical importance. The percentage of interactions with significant clinical importance was higher in prescriptions of medical specialists and of those, cardiologists and internists ranked top on the list, while dermatologists ranked the lowest. The most common interacting combination prescribed was digoxin and furosmide in 2007-2008, and captopril and triamteren in 2008-2009. Moreover, this study showed that polypharmacy was an important factor which led to DDIs. Drug interactions were common among outpatients prescribed multiple medications and the rate of DDIs increased with the number of drugs prescribed. It is our opinion that by being up-to-date on drug information and participating in related educational classes and workshops, physicians can increase the chances of choosing the correct drug treatment and hence significantly decrease possible DDIs side effects.