Cmin
Also known as: trough concentration · minimum plasma concentration
The lowest plasma concentration of a peptide during a dosing interval, typically measured immediately before the next dose.
Cmin — the trough — is where most protocols quietly fail. If Cmin falls below the compound's effective receptor-engagement threshold, the researcher experiences a 'dead window' between doses where the compound is technically present but not producing measurable effect. This is the single most common failure mode in low-frequency dosing schedules.
Established protocols solve the Cmin problem three ways: increasing dose frequency, increasing dose size, or switching to a long-half-life analog. The third option is why Tirzepatide displaced Liraglutide for most research contexts — the weekly Cmin of Tirzepatide is cleaner than the daily Cmin of Liraglutide at equivalent weekly exposure.
Related Terms
Cmax
The maximum plasma concentration reached after a single dose of a peptide.
Steady State
The point at which the rate of peptide administration equals the rate of elimination, producing a stable average plasma concentration.
Half-Life
The time required for the concentration of a peptide in the body to fall to half of its peak value.
AUC (Area Under Curve)
The integrated total exposure of the body to a peptide over time, calculated as the area under the concentration-time curve.
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