Therapeutic substitution practices in short-term hospitals.

Hospital policies concerning the automatic interchange of therapeutically equivalent drugs were examined. A questionnaire was sent to the chief pharmacists at 6326 shot-term hospitals throughout the United States. The survey items solicited demographic data and formulary policies on generic and therapeutic substitution. A total of 2437 (39%) usable questionnaires were returned. Approximately 40% of the hospitals reported that their formulary system allows the stocking of a single product to represent a given therapeutic category. A total of 751 hospitals reported that their formulary system allows automatic dispensing of the therapeutically equivalent drug product without contacting the physician for permission. Therapeutic substitution was found particularly prevalent in federally owned hospitals. There were regional variations in the existence of therapeutic substitution. Factors that appeared to be associated with therapeutic substitution were: drug use review activity, medical school affiliation, existence of a formulary system, perceptions of favorable view by the state board of pharmacy, and favorable perception of the savings generated through bid purchasing. Reasons for not engaging in therapeutic substitution included the following: (1) would not be accepted by the physicians, (2) interferes with physicians' right to select the drug, (3) unnecessary risk of civil liability, (4) violation of laws, and (5) expected benefits do not justify the cost. Most respondents thought that physicians are usually aware of therapeutic substitutions that occur. Although they were a minority, a large percent of the respondents had a formulary system that allowed automatic interchange of generically inequivalent products within a therapeutic class of drugs. The influence of therapeutic substitution on drug therapy outcomes and cost savings need to be evaluated.