Drug-drug interactions leading to QT-prolongation: current practice in psychiatric hospitals
Foulon, Veerle × Willems, Rik R De Boever, Willy W De Voght, Mieke M De Vos, Marc M Pauwels, Eric E Vrijders, Danny D Reyntens, Johan J #
Koninklijke Nederlandse Maatschappij ter Bevordering der Pharmacie
Pharmacy World & Science vol:32 issue:2 pages:291-291
European Symposium on Clinical Pharmacy edition:38 location:Geneva date:November 2009
Introduction and objectives
The growing availability of psychopharmacological agents, in line with the frequent need for the use of drug combinations, has made the treatment options for psychiatric patients very complex and increases the risk for potentially severe drug-drug interactions. The literature on adverse drug events in mental health settings however, is very scarce.
The aim of this study was to provide data on the frequency and nature of drug-drug interactions in medication records of psychiatric in-patients and to determine how drug-drug interactions (i.c. drug combinations leading to QT-prolongation) are monitored in mental health settings.
The study consisted of 2 different parts:
1) Screening of medication profiles of psychiatric in-patients for drug-drug interactions using Delphi, an on-line interaction detection tool
2) Written survey of physicians’ and pharmacists’ current practice in monitoring drug-drug interactions
This study was performed in pscychiatric hospitals in Flanders, Belgium. Questionnaires were distributed through the responsible pharmacist of each of the hospitals. The retrospective analysis of the medication profiles was limited to 6 psychiatric hospitals.
Main outcome measures
1) The frequency and nature of drug-drug interactions in medication profiles of psychiatric in-patients
2) Physicians’ and pharmacists’ current practice in monitoring drug-drug interactions
Potentially severe or very severe drug-drug interactions were found in 49.8% of medication profiles of psychiatric in-patients. 12% of these interactions potentially lead to QT-prolongation or Torsade de Pointes.
Physicians and pharmacists from psychiatric hospitals underestimate the risk for QT-prolongation. Only in 3 out of 12 hospitals, physicians claimed to take an ECG whenever starting a drug which may prolong the QT-interval. In 3 other hospitals, an ECG was never taken. The majority of physicians and pharmacists indicated that monitoring of drug-drug interactions is very important, and that the final responsibility is with the physician. Although physicians expect support from the pharmacist in medication surveillance, half of the pharmacists mentioned never being contacted by physicians concerning drug-drug interactions.
This study showed that almost half of the patients in psychiatric hospitals receive a combination of potentially interacting drugs. As current practice and expectations in monitoring drug-drug interactions are very diverse, clear arrangements about the medication surveillance system in psychiatric hospitals are needed.