Background Drug-drug interactions may increase the risk of adverse events. Understanding the pharmacokinetic and pharmacodynamic properties of drugs and their interaction mechanisms is fundamental to optimising therapeutic results. The benefits of statins in the treatment and prevention of cardiovascular disease are well documented. Although overall safe, statins produce a wide range of adverse effects that are known to be potentiated by certain drug interactions. Concomitant use of simvastatin with a potent CYP3A4 inhibitor (inCYP3A4) is considered a clinically significant pharmacokinetic interaction, and therefore this combination is contraindicated.

Purpose To evaluate the efficacy of a recently implemented safety alerts system in reducing the prevalence of co-prescription of simvastatin and inCYP3A4.

Materials and methods After an extensive bibliographic review of the drug interaction classifications, a computerised system was implemented to alert for the risk of co-prescription of simvastatin and an inCYP3A4. All patients with a simvastatin prescription admitted to Centro Hospitalar de Lisboa Ocidental, between April 2013 – October 2013, were included. Data were obtained by consulting the Pharmaceutical Services’ records. Co-prescription prevalence rates were assessed for a three-month period, before and after implementation of safety alerts.

Results In this study, 1707 patients (55.4% male, mean age 72.7 ± 12.2 [27–103] years) were included in pre-implementation phase (PEP) and 1225 patients (56.0% male, mean age 72.3 ± 12.6 [15–105] years) in the post-implementation phase (POP). In PEP, co-prescription was identified in 110 patients (mean duration 4.9 ± 7.1 days, [1–65]) and in POP, 13 patients (mean duration 3.8 ± 3.9 days, [1–15]). Co-prescription rates in PEP and POP were 6.44% and 1.06% respectively, which represents an 83.53% reduction.

Conclusions The safety alerts system implemented seems to be an effective strategy in reducing incidence of simvastatin and inCYP3A4 co-prescription, and therefore may increase patient safety in hospital. Our study will be extended to a one-year period (January 2013–2014) in order to evaluate the robustness of the implemented strategy.

No conflict of interest.