Pharmacodynamic factors of antibiotic efficacy.

The primary focus of the pharmaceutical industry in past years has been on developing more potent antibiotics rather than on establishing optimum therapy with currently available agents. Concepts that can be used to tailor patient- and pathogen-specific antimicrobial regimens include concentration-dependent killing, concentration-independent killing, and postantibiotic effect. It is possible to administer single daily doses (SDD) of aminoglycosides; however, a fixed SDD regimen cannot meet the goals for therapy in all patients. Instead, it is necessary to consider both pharmacodynamic concepts and pharmacokinetic principles. Even with tailored, patient-specific regimens, however, limitations exist with antibiotic therapy alone. Immunotherapy, used as an adjunct to antimicrobial therapy, may play a role in improving patient outcomes.