Peak Plasma Concentration (Cmax)
The highest concentration of a drug achieved in the blood after administration, before elimination begins to reduce levels. Cmax is an important pharmacokinetic parameter that, along with AUC, characterises a drug's absorption profile and helps determine appropriate dosing.
Technical Context
Cmax depends on the dose, rate of absorption, and rate of elimination. For SC peptide injections, Cmax typically occurs 1-8 hours after injection (Tmax). For oral peptides, Cmax depends on gastric emptying and absorption kinetics. For IV bolus, Cmax occurs immediately. Cmax is clinically relevant because side effects often correlate with peak concentrations — the nausea associated with GLP-1 RAs may be partly related to Cmax. Extended-release formulations and albumin-binding strategies blunt Cmax (producing flatter pharmacokinetic profiles), which can improve tolerability. Cmax and AUC together define the drug's exposure profile and are both required for bioequivalence determinations.