Antimicrobial serum concentration monitoring

Toxicity Monitor and assess for adverse effects and evaluate antimicrobial serum concentrations when appropriate to minimize toxicity and improve outcomes... 

For most antimicrobial agents, the relation between dose and therapeutic outcome is well established, and serum concentration monitoring is unnecessary for these drugs. To justify routine serum concentration monitoring, it should be established (1) that a direct relationship exists between drug concentrations and efficacy or toxicity (2) that substantial interpatient variability exists in serum concentrations on standard doses (3) that a small difference exists between therapeutic and toxic serum concentrations (4) that the clinical efficacy or toxicity of the drug is delayed or difficult to measure and (5) that an accurate assay is available. 

Vancomycin serum concentration monitoring can either be minimized or avoided entirely for many patients who are treated with this antimicrobial. 

The clinician should have an understanding of in vivo antimicrobial agent disposition in order to select the most appropriate therapy for a given infection and to help monitor for clinical or bacteri-ologic efficacy. Serum concentration monitoring is the most common method used to attempt to maximize efficacy and minimize toxicity of antimicrobials. Since most antimicrobials are well tolerated at their usual doses, only a select few agents (e.g., aminoglycosides, chloramphenicol, and vancomycin) are monitored routinely in the current clinical environment. There are a number of direct and indirect methods that are used to quantify the concentration of antimicrobial in an experimental sample. 

Serum concentrations of the antimicrobial should generally exceed the MBC of the organism however, in practice this principle is usually not helpful in monitoring patients with endocarditis. 

Routine monitoring of serum concentrations is currently used for a select few antimicrobials (e.g., aminoglycosides, chloramphenicol, and vancomycin) in an attempt to minimize toxicity and maximize efficacy. 

Peak and/or trough concentrations are monitored rontinely for only a select few antimicrobials (e.g., aminoglycosides and vancomycin) during the contemporary management of infections. It is crucial for the health care team to ensure that the antimicrobiars administration time and serum sample time(s) are meticulously recorded because even small errors in recording these (e.g., 1 hour) may have a substantial impact on the calcnlation of pharmacokinetics for antibiotics such as the aminoglycosides, which have relatively short elimination half-lives. 

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