Use of an online surveillance system for screening drug interactions in prescriptions in community pharmacies.

OBJECTIVE: Computerised surveillance systems have become available for screening potential adverse drug interactions during drug prescribing and dispensing. The purpose of this study was to analyse the frequency and profile of alerts given by one such system in two community pharmacies in Finland.

METHODS: In a prospective study, all interaction alerts given by the surveillance system were collated during September-November 2004 in two community pharmacies in Southern Finland. The alerts were categorised into four classes (A-D) according to their clinical significance.

RESULTS: During the 3-month study period, a total of 39,539 prescriptions were dispensed. The system flagged 3,861 prescriptions as having potential interactions (9.8% of all prescriptions). Since one prescription could be the source of several interaction alerts, a total of 5,647 alerts were given. The clinically most significant interactions (class D) represented 0.4% of prescriptions (3.0% of all interactions). Class C alerts were most prevalent (9.4% of all prescriptions, 65.9% of all interactions). The most commonly encountered interaction in class D was between warfarin and non-steroidal anti-inflammatory drugs.

CONCLUSIONS: Although the incidence of potentially most hazardous interactions in prescriptions is rather low in this study (0.4%), the overall incidence is relatively high (9.8%). Implementation of the interaction surveillance system in the participating pharmacies makes it possible to study in the future in quantitative terms whether the quality of drug dispensing is improved.