Drug interaction in family medicine

Abstract

Summary: To verify the existence and ascertain the frequency of drug-drug pharmacokinetic interactions in the hepatic cytochrome chains. Material and methods: 15 Family Doctors from the centre of Portugal agreed on a study of their two days pharmacological prescriptions, issued only to their ambulatory patients. The data from prescriptions were then studied by a non prescribing GP by means of a table of pharmacokinetic drug-drug interactions table, published in http://www.druginteractions.com. Results: The prescriptions of 484 patients (82,6%) mean age 57,7±19,8 years (183 males) of the total patients consulted were studied. We observed that there is a rise in the number of prescribed drugs with age, although the mean drug prescription was 2,2±1,4 and the mean daily dosage was 3,2±2,2. Anti-hypertensives were the most prescribed drugs, accounting for 61,0% of the total. In 101 patients (20,9%) a pharmacokinetic drug-drug interaction was found. In total 142 drug-drug interactions were discovered, 68,3% of which of simple co-metabolism, 28,1% of cytochrome inhibition by a drug and 3,5% of cytochrome induction. For a total of 241 prescribed drugs, drug metabolic cytochrome was known for 86 (35,7%). Conclusions: Although no patient was specifically followed for the discovery of any problem due to the drugs prescribed, namely adverse drug reaction therapeutic inefficiency, and this paper being based on a two days sample of prescription, it is nevertheless important that continuous medical education be performed to provide doctors the best possible knowledge to prevent harmful drug interactions. Best attention should be put in the information to the medical community delivered by regulatory authorities or by the industry.