[Drug-drug-interactions in psychiatry]

In daily practice of psycho-pharmacotherapy most patients are under polypharmacy which may result in potentially harmful drug-drug interactions. Therefore, we investigated if the risk of drug-drug interactions can be reduced by a consultant clinical pharmacist for the physicians on psychiatric wards.

Drug-drug-interactions and adverse drug reactions of patients on 2 psychiatric intensive care units were investigated retrospectively in 2008 and 2009. Before the second investigation period, a special training was performed and during this period a pharmacist supported the physicians regarding drug therapy.

After the introduction of a pharmacist on the ward and 2 teaching lessons relevant drug interactions were reduced by 78 % (p < 0.001), the number of all interactions by 44 % (p < 0.001). The total number of drug interactions decreased by the training sessions, which were offered shortly before starting the second observation period, from 3.4 interactions/patients in 2008 to 2.2 interactions/patients in 2009 (p < 0.04).

A clinical pharmacist on the ward can contribute to a higher drug therapy safety in psychiatric wards. An interdisciplinary approach can relieve the physicians' daily work. The drug therapy can be improved by continuous teaching sessions about drug interactions.