Clinical aspects of therapeutic substitution.

A variety of problems are associated with the operation, quality, costs, and benefits of therapeutic substitution programmes. Adequate communication of procedures, events, and failures are essential features of a safe therapeutic substitution policy. However, case reports of suboptimal therapy and differences in pharmacological profiles of related agents indicate the potential for clinical nonequivalence even between similar drugs of a class. Suboptimal or failed therapy associated with such nonequivalence may offset savings in drug costs resulting from therapeutic substitution. Thus, consultation on behalf of each patient is necessary for optimal therapy and maximum cost savings. Currently, there are no data on the interchangeability of specific agents of a class and the effects of therapeutic substitution on overall treatment costs. Thus, the health and economic outcomes of therapeutic substitution policies are unknown.