plasma level
The concentration of a medication in blood plasma, used for therapeutic monitoring.
Full Definition
The measurable concentration of a medication or its active metabolites in blood plasma, typically expressed in nanograms per milliliter (ng/mL) or micrograms per liter (μg/L). Plasma levels are crucial in psychopharmacology for medications with narrow therapeutic indices like lithium, or when therapeutic response is suboptimal despite adequate dosing. These measurements help guide dose adjustments, confirm medication adherence, and investigate potential toxicity. The relationship between plasma levels and therapeutic response varies significantly among different psychiatric medications and individual patients.
Usage
Usage note: Often used interchangeably with 'serum level' though technically distinct. Ensure units are specified when reporting numerical values.
In Context
- "The patient's lithium plasma level of 1.3 mEq/L indicated the need for dose reduction." — Laboratory report interpretation
- "Routine plasma level monitoring is not recommended for most antidepressants." — Clinical practice guideline