Implementation of an outpatient prescription drug formulary in a managed-care system

The development and implementation of an outpatient prescription formulary in an independent-practice model health maintenance organization (HMO) and the role of the pharmacy and therapeutics (P&T) committee in the process are described. Approximately 600 physicians provide medical care and control the operation of this independent practice association (IPA); of approximately 45,000 members, 95% are eligible for outpatient prescription services provided by one of 188 local pharmacies. The formulary, which is restricted to noninjectable medications, was developed by a P&T committee composed of eight IPA physicians, a representative of the local pharmaceutical association, and three staff members of the IPA's pharmacy department. The printed version of the formulary indexed almost 1800 items and included only commonly used medications to limit its size. Requests for additions or deletions of drugs were evaluated monthly. After a four-month period during which physicians were asked to comply with the formulary, mandatory compliance was imposed, with a limit of 16 nonformulary prescriptions per physician per month being allowed. Based on the results of an informal survey, the physicians indicated that the formulary was relatively easy to adjust to (44.1%), somewhat difficult to work with (43.6%), and somewhat disruptive to their prescribing practices (55.3%). When asked about quality of patient care, 74.3% indicated there was no change. Physician compliance with the formulary system increased from 88.0% to 96.1% after the formulary was mandated by the IPA. Under the direction of the P&T committee, a formulary was implemented effectively in this HMO outpatient prescription drug program.