To adequately evaluate the appropriate dosage levels of many drugs, the collection and testing of specimens for trough and peak levels is necessary. The trough level is the lowest concentration in the patient's bloodstream, therefore, the specimen should be collected just prior to administration of the drug.

Why are peak and trough levels drawn for vancomycin?

To improve antibiotic penetration and optimize the likelihood of achieving pharmacokinetic and pharmacodynamic targets, trough levels of 15 to 20 mg/L are recommended for pathogens with a vancomycin minimum inhibitory concentration (MIC) of 1 mg/L or higher and for complicated infections such as endocarditis, ...

How is a trough level drawn?

A trough level is drawn immediately before the next dose of the drug is administered. A peak level is drawn 1 to several hours after the drug is administered (depending on the drug).