The therapeutic monitoring of antimicrobial agents

Aims To review the basis and optimal use of therapeutic drug monitoring of antimicrobial agents. Methods Antimicrobial agents for which a reasonable case exists for therape utic drug monitoring are reviewed under the following headings: pharmacokin etics, why monitor, therapeutic range, individualization of therapy, sampli ng times, methods of analysis, interpretative problems and cost-effectivene ss of monitoring. Results There is a strong historical case for monitoring aminoglycosides. T he recent move to once-daily dosing means that criteria for therapeutic dru g monitoring need to be redefined. Vancomycin has been monitored routinely but many questions remain about the most appropriate approach to this. A ca se can be made for monitoring teicoplanin, flucytosine and itraconazole in certain circumstances. Conclusions The approach to monitoring aminoglycosides is being redefined i n the light of once daily dosing. It may be that less stringent monitoring is required in some circumstances but toxicity, especially ototoxicity, rem ains a problem with these drugs. Monitoring to avoid high AUCs (areas under the concentration-time curve) is recommended. The ideal method for monitor ing vancomycin remains to be defined although a reasonable case exists for measuring trough concentrations, mainly to ensure efficacy. Teicoplanin is sometimes monitored to ensure efficacy while flucytosine may be monitored t o avoid high concentrations associated with toxicity. Itraconazole has vari ous pharmacokinetic problems and monitoring has been suggested to ensure th at adequate concentrations are achieved.