Short-lived effects of a formulary on anti-infective prescribing--the need for continuing peer review?

Because of the introduction of indicative drug budgets in the UK and their likely association with prescribing from a drug formulary, we have studied the effect of the introduction without continued reinforcement of a voluntary practice formulary on antimicrobial prescribing in a group practice. Detailed prescribing feedback for two matched periods before and after the launch of the Northern Ireland Faculty of the Royal College of General Practitioners practice formulary was compared. The parameters chosen were adherence to the formulary, generic prescribing and costs. A slight increase in prescriptions dispensed (3.5%) was observed between the two periods but prescribing costs increased by 32%. There was a 5.9% fall in the number of prescriptions for formulary agents following the launch of the formulary and a major increase (60%; P < 0.01) in the use of non-formulary antimicrobials particularly penicillins and tetracyclines. It was concluded that the high level of formulary prescribing prevalent during the production of the formulary was not maintained following its launch probably because of the lack of reinforcement.