BACKGROUND/JUSTIFICATION: Studies point up the serious adverse reactions (ADR) as one of the six main causes of death of hospitalized patients in the United States. The most frequent ADR include the drug interaction. METHODS: twenty most used medications were compared, in a certain period of time, at the clinical sector of São Lucas Universitary Hospital of PUC-RS, to the fourteen most used ones at the Ambulatório de Depressão (ADe) of the same hospital. The research gathered information published since 1990 in Medline and Lilacs. RESULTS: several drug interactions were found among many of the studied medications, often involving the Cytochrome P450 System. CONCLUSION: the update of the medication on clinic use goes further than the expected results or the most frequent collateral effects.
Drug interaction; CYP; Cytochrome P450
