Therapeutic Substitution and Formulary Systems

T he practice of therapeutic drug substitution has become common throughout the United States, often without the awareness of many physicians. It occurs to some extent in more than 52% of the nation’s acute care hospitals and more than 30% of health maintenance organizations (HMOs) (1, 2). Therapeutic substitution entails dispensing a drug different in chemical structure from the one originally prescribed. The substitute must be from the same therapeutic class (therapeutic alternate) and have the same pharmacodynamic and pharmacokinetic properties (for example, cefazolin for cefotaxime; cimetidine for ranitidine). Therapeutic substitution originates in an institution’s formulary system. Arising from the need for rational drug therapy within the context of increasing medical care costs, the formulary system is devised and approved by an institution’s medicai staff for the objective evaluation, selection, and use of drugs. An effective formulary system permits a high quality of care while providing economic advantages. This is achieved in part through the development and enforcement of policies preventing the administration of drug therapies likely to lead to suboptimal, hazardous, or unnecessarily costly health outcomes. In addition, the selection of cost-effective formulary drugs that meet the needs of the institution can heip offset the 6YY0 rise in producers’ prescription drug prices that has occurred since 1982 (3). The medical staff oversees the formulary system through its Pharmacy and Therapeutics Committee. The Committee, in addition to serving in an advisory capacity, monitors the procurement, prescription, dispensation, and administration of formulary and nonformulary drug products. These relationships and responsibilities have been adopted as requirements for hospitals accredited by the Joint Commission on Accreditation of Healthcare Organizations (4). The Pharmacy and Therapeutics Committee also serves to fulfill the educational needs of medical staff members and other professionals regarding drugs and drug use. This may include the planning and establishment of innovative programs to assist institutional prescribers in providing optimal drug therapy (5, 6). This paper describes the current practice of therapeutic substitution, its potential benefits and hazards, and