Background Metamizole (MTZ) is widely used after surgery as an analgesic, antipyretic and spasmolytic drug. However complications such as agranulocytosis, anaphylactic choc and renal impairments have been reported. This medication has therefore been withdrawn in several countries because of those side effects. A recent study showed a 8 times increased of MTZ use within the last 10 years in Switzerland. In our hospital, the Drug and Therapeutic Committee recommends to use MTZ only in the cases where no other option is possible and to use it no longer than 3 days.

Purpose Analysis of MTZ prescription and administration in the 3 services main users and comparison with the use in other Swiss hospitals.

Materials and methods The medical records of all the patients discharged from the services of orthopaedic surgery, traumatology and visceral surgery have been analysed over a 3-week period. Data on duration of treatment, doses, frequency of use and way of administration of MTZ have been recorded as well as details on discharge prescriptions.

A survey has also been sent to all Chief-Pharmacists of the Swiss hospitals in order to evaluate the practices in their institution.

Results In total, 303 patients’ files have been reviewed. When used after surgery MTZ was used as first intention analgesic in 95% of cases. The duration of MTZ prescription was longer than 3 days in 33% of patients. The usual daily dose was 3 g/day and the MTZ was given orally in 94% of cases. 33% of patients who were prescribed MTZ during the hospital stay kept it on the discharge prescription.

28/47 hospitals answered our national survey. Among them 95% were using MTZ frequently to very frequently. Guidelines aimed at limiting MTZ use were available in 43% of the hospitals.

Conclusions MTZ is very frequently used as first line post surgery analgesic in the CHUV as in many other Swiss hospitals instead of other safer analgesics. Publication of guidelines does not seem to limit the prescription. Discussions have to be conducted with the prescribers in order to redefine the place of MTZ after surgery.

No conflict of interest.