Impact of hospital pharmacist interventions on the combination of citalopram or escitalopram with other QT-prolonging drugs

Background Citalopram and escitalopram can both induce dose-dependent QT prolongation. The risk of arrhythmia may be increased with concomitant use of other drugs that induce QT prolongation. Objective To evaluate the prevalence and impact of pharmacist interventions on the combination of citalopram or escitalopram with other drugs that induce QT prolongation. Setting A French hospital with 517 computerized beds. Method All cardiac adverse drug reactions (ADRs) related to citalopram or escitalopram reported to the French pharmacovigilance database (FPDB) were analyzed. Then, over a 6-month period, all computerized prescriptions including citalopram or escitalopram and drug–drug interactions (DDI) were analyzed by pharmacists using a computerized provider order entry system (DXCare^®, Medasys). Results Only 27 cardiac ADRs related to citalopram or escitalopram were reported in the database. Among the 57,857 prescriptions and 2116 contraindicated DDIs (3.7 %) that were analyzed. 444 DDIs (0.8 %) were considered to be clinically relevant by pharmacists and physicians and 168 (i.e., approximately 30 %) were related to a combination including citalopram or escitalopram. Most of the prescriptions related to DDIs including citalopram or escitalopram were discontinued in response to a pharmacist intervention when initiated during the hospital stay. Conclusion A high number of hospital prescriptions including citalopram or escitalopram with another QT-prolonging drug occurred, highlighting the importance of involvement of clinical pharmacists in prevention of potential ADRs related to such contraindications.