Controversies in antimicrobial therapy: formulary decisions on third-generation cephalosporins.

Factors affecting the admission of antimicrobial agents to hospital formularies are discussed, using third-generation cephalosporins as examples. Inappropriate antimicrobial therapy is costly in terms of wasted drugs, ineffective therapy, and drug toxicity. In 1984, 10 of the top 15 drug products (in sales to hospitals) were antimicrobial agents; these accounted for $1 billion in sales. Since third-generation cephalosporins are very similar in terms of spectra, clinical efficacy, and safety, they are useful in illustrating the process a hospital might use in deciding which individual agent to admit to a formulary. Five factors should be considered in formulary evaluations of antimicrobial agents: in vitro activity, pharmacokinetic disposition, adverse effects, clinical efficacy, and total economic impact. As applied to third-generation cephalosporins, this decision analysis leads to the conclusion that these agents should be considered therapeutic alternates. The decision would then rest solely on the institution-specific factors of microbial susceptibility patterns, patient case-mix, and acquisition costs. Antimicrobial agents account for the largest financial expenditure among hospital drug products; a set of these agents should be selected carefully to meet the needs of the individual institution.