What principle is being assessed when looking for Ariana's blood levels two hours after vancomycin infusion completion?

The principle being assessed two hours after the completion of Ariana's vancomycin infusion is the peak level. When monitoring drugs like vancomycin, peak levels represent the maximum concentration of the drug in the bloodstream after administration. This timing is crucial as it allows healthcare professionals to determine whether the drug has reached an effective concentration for its therapeutic effects.

Peak levels are typically evaluated to ensure that the medication is not only effective but also to prevent toxicity. Getting this measurement consistently at the right time is essential for drugs with a narrow therapeutic index, such as vancomycin.

In contrast, trough levels would be assessed just before the next dose is given, to ensure that drug concentrations do not fall too low between doses. The additive effect refers to the combined effect of two drugs which can sometimes enhance efficacy or toxicity, and drug tolerance refers to the body's decreasing response to a drug after prolonged use, neither of which applies to the timing assessment of drug levels following infusion.