Pharmacokinetics
Definition
Pharmacokinetics (PK) is the study of how the body absorbs, distributes, metabolises, and excretes a compound over time. Often summarised as “what the body does to the drug,” it is distinct from pharmacodynamics (what the drug does to the body). For peptide research, PK parameters are critical for understanding dosing, timing, and bioavailability.
Key Pharmacokinetic Parameters
The core PK metrics relevant to peptide research include:
- Cmax — Peak plasma concentration after administration
- Tmax — Time to reach peak concentration
- Half-life (t½) — Time for plasma concentration to decrease by 50%
- AUC (Area Under the Curve) — Total drug exposure over time
- Clearance — Rate at which the compound is removed from circulation
- Volume of distribution (Vd) — Extent of distribution into tissues beyond plasma
Peptide-Specific PK Considerations
Peptides present unique PK challenges. Most are rapidly degraded by proteases, resulting in short half-lives unless structurally modified. Route of administration heavily influences PK profiles — subcutaneous injection creates a depot effect with slower absorption compared to intravenous delivery. Modifications like PEGylation, lipidation, and albumin binding are used to extend circulation time and improve PK profiles in research compounds.
Related Peptides
Peptide profiles that reference “Pharmacokinetics” in their research content.