Prevalence of the prescription of potentially interacting drugs

Elena Tragni, Manuela Casula, Vasco Pieri, Giampiero Favato, Alberico Marcobelli, Maria Giovanna Trotta, Alberico Luigi Catapano

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The use of multiple medications is becoming more common, with a correspondingly increased risk of untoward effects and drug-related morbidity and mortality. We aimed at estimating the prevalence of prescription of relevant potentially interacting drugs and at evaluating possible predictors of potentially interacting drug exposure. We retrospectively analyzed data on prescriptions dispensed from January 2004 to August 2005 to individuals of two Italian regions with a population of almost 2.1 million individuals. We identified 27 pairs of potentially interacting drugs by examining clinical relevance, documentation, and volume of use in Italy. Subjects who received at least one prescription of both drugs were selected. Co-prescribing denotes ‟two prescriptions in the same day”, and concomitant medication ‟the prescription of two drugs with overlapping coverage”. A logistic regression analysis was conducted to examine the predictors of potential Drug-Drug Interaction (pDDIs). 957,553 subjects (45.3% of study population) were exposed to at least one of the drugs/classes of the 27 pairs. Overall, pDDIs occurred 2,465,819 times. The highest rates of concomitant prescription and of co-prescription were for ACE inhibitors+NSAIDs (6,253 and 4,621/100,000 plan participants). Considering concomitance, the male/female ratio was <1 in 17/27 pairs (from 0.31 for NSAIDs-ASA+SSRI to 0.74 for omeprazole+clopidogrel). The mean age was lowest for methotrexate pairs (+omeprazole, 59.9 years; +NSAIDs-ASA, 59.1 years) and highest for digoxin+verapamil (75.4 years). In 13/27 pairs, the mean ages were ÔëÑ70 years. On average, subjects involved in pDDIs received ÔëÑ10 drugs. The odds of exposure were more frequently higher for age ÔëÑ65 years, males, and those taking a large number of drugs. A substantial number of clinically important pDDIs were observed, particularly among warfarin users. Awareness of the most prevalent pDDIs could help practitioners in preventing concomitant use, resulting in a better quality of drug prescription and potentially avoiding unwanted side effects.
    Original languageEnglish
    Article numbere78827-e78827
    JournalPLoS ONE
    Volume8
    Issue number10
    DOIs
    Publication statusPublished - Oct 2013

    Keywords

    • Health services research

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