The therapeutic monitoring of antimicrobial agents.
OBJECTIVE
To review the basis and optimal use of therapeutic drug monitoring of antimicrobial agents.


METHODS
Antimicrobial agents for which a reasonable case exists for therapeutic drug monitoring are reviewed under the following headings: pharmacokinetics, why monitor, therapeutic range, individualization of therapy, sampling times, methods of analysis, interpretative problems and cost-effectiveness of monitoring.


RESULTS
There is a strong historical case for monitoring aminoglycosides. The recent move to once-daily dosing means that criteria for therapeutic drug monitoring need to be redefined. Vancomycin has been monitored routinely but many questions remain about the most appropriate approach to this. A case can be made for monitoring teicoplanin, flucytosine and itraconazole in certain circumstances.


CONCLUSIONS
The approach to monitoring aminoglycosides is being redefined in the light of once daily dosing. It may be that less stringent monitoring is required in some circumstances but toxicity, especially ototoxicity, remains a problem with these drugs. Monitoring to avoid high AUCs (areas under the concentration-time curve) is recommended. The ideal method for monitoring 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 to avoid high concentrations associated with toxicity. Itraconazole has various pharmacokinetic problems and monitoring has been suggested to ensure that adequate concentrations are achieved.
Begg
E J
EJ
Department of Clinical Pharmacology, Christchurch Hospital, Christchurch, New Zealand. evan.begg@chmeds.ac.nz
Barclay
M L
ML
Kirkpatrick
C M
CM
D000368:Aged; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use; D000935:Antifungal Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D019540:Area Under Curve; D003362:Cost-Benefit Analysis; D016903:Drug Monitoring / Q000379:methods*; D017248:Enzyme Multiplied Immunoassay Technique; D006801:Humans
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents