[Potential drug-drug interactions among elderly using antihypertensives from the Brazilian List of Essential Medicines].

The aim of this study was to estimate the prevalence of potential interactions between antihypertensives and other drugs. A household survey was conducted with individuals 60 years or older residing in Rio de Janeiro, Brazil. Potential moderately or very severe drug-drug interactions with antihypertensives, documented as suspected, probable or established, were identified. A total of 577 elderly were interviewed (mean age = 72 years), 45.2% of whom were using antihypertensives, of which 31.0% were subject to potential drug-drug interactions. Most of the interactions were moderately severe. Compared to the other elderly, those with potential drug-drug interactions showed more than fourfold odds of using five or more medicines and more than twofold odds of having been hospitalized in the previous year. Among the most frequent pairs of interactions, 75% cause a reduction in the hypotensive effect (65/87), which can result in low effectiveness of blood pressure control, prescribing of more drugs, and risk of other adverse events and interactions.