Drug interactions
may represent an iatrogenic risk that should be controlled in
community pharmacies at the dispensing level.
Aim: We analyzed the association between potential drug-drug interactions
(DDIs) and negative clinical outcomes.
Methods: We used dispensing data from two community pharmacies:
instances where drug dispensing was associated with a potential
DDI and a comparison group of randomized dispensing operations
with no potential DDI. In cases where potential DDIs were detected,
we analyzed the underlying negative clinical outcomes. Age and
gender data were included in the analysis.
Results: During the study period, we registered 417 potential
DDIs. The proportion of women and age were higher in the study
group than in the comparison group. The average potential DDIs
per patient was 1.31 (SD=0.72). The Consejo General de Colegios
Oficiales de Farmacéuticos (CGCOF) database did not produce
an alert in 2.4% of the cases. Over-the-counter medication use
was observed in 5% of the potential DDI cases. The drugs most
frequently involved in potential DDIs were acenocoumarol, calcium
salts, hydrochlorothiazide, and alendronic acid, whereas the most
predominant potential DDIs were calcium salts and bisphosphonates,
oral antidiabetics and thiazide diuretics, antidiabetics and glucose,
and oral anticoagulant and paracetamol. The existence of a drug-related
negative clinical outcome was observed only in 0.96% of the potential
DDI cases (50% safety cases and 50% effectiveness cases).
Conclusions: Only a small proportion of the detected potential
DDIs lead to medication negative outcomes. Considering the drug-related
negative clinical outcomes encountered, tighter control would
be recommended in potential DDIs with NSAIDs or benzodiazepines.
