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Peak-Trough Ratio

Meaning

Peak-Trough Ratio is a pharmacokinetic metric used in clinical pharmacology to assess the fluctuation of a drug’s concentration in the bloodstream over a single dosing interval, often employed to evaluate the suitability of a dosing regimen. It is calculated by dividing the maximum concentration (Peak) achieved after administration by the minimum concentration (Trough) reached just before the next dose. A low ratio indicates a relatively stable drug level, which is often desirable for agents with a narrow therapeutic window, while a high ratio suggests significant concentration variability. In hormonal therapy, this ratio is critical for ensuring sustained, physiological levels of an administered hormone or peptide without causing transient supraphysiological spikes or sub-therapeutic dips.