Objectives: To investigate the number of different drugs prescribed per dispensing unit and to analyse the influence of practice characteristics on this number.
Design: Register analysis based on the Odense Pharmacoepidemiological Database (OPED).
Setting: General practices in the County of Funen, Demnark.
Subjects: 173 general practices (99 single-handed and 74 group practices).
Main outcome measures: Number of different drugs prescribed per dispensing unit.
Results: The number of different drugs prescribed per dispensing unit varied nearly fourfold (range 102-381) and four practice characteristics were able to predict 74% of this variation. Practices with several doctors, a high number of patients listed per doctor, a high percentage of elderly individuals, and a heavy workload showed the highest number of different drugs prescribed.
Conclusion: As the quality of drug prescribing is associated with the use of a limited number of drugs, it is suggested that GPs should agree on a formulary containing the most essential drugs in primary health care.