Prescribing safely in elderly psychiatric wards: Survey of possible drug interactions

Abstract

Aims and method: A cross-sectional survey of patient drug prescriptions on two elderly psychiatric wards was carried out to estimate the potential of drug-drug interactions. Two standardised data-bases, British National Formulary (BNF; British Medical Association & Royal Pharmaceutical Society of Great Britain, 2007) and UptoDate (www.uptodate.com/), were employed. Results: A majority (96%) of drug prescriptions in our study could potentially cause drug-drug interactions. Most patients were on multiple drugs (on average eight drugs per patient). There was poor concordance between the two databases: BNF picked up fewer cases of potential drug-drug interactions than UptoDate (43 v. 152 instances) and they also estimated the potential for hazardousness differently. Clinical implications: Polypharmacy is common in elderly psychiatric patients and this increases the possibility of a drug-drug interaction. Estimating the risk of interactions depends on a sound knowledge in therapeutics and/or referring to a standardised source of information. The results of this study question the concordance of two well-referenced databases.