Pharmacokinetics
The study of how the body absorbs, distributes, metabolizes, and excretes a drug or compound over time — often summarized as ADME.
Pharmacokinetics (PK) describes what the body does to a compound: how quickly it enters the bloodstream (absorption), how it moves through tissues (distribution), how it is chemically modified (metabolism), and how it is removed from the body (excretion). These four processes together determine the concentration-time profile of a compound in the blood and tissues.
For research peptides, PK properties vary significantly by compound and route of administration. Subcutaneous injection of peptides typically results in absorption over 15–60 minutes with peak plasma concentrations occurring shortly after. Short half-lives — common among GHRPs and GHRHs — mean plasma levels fall quickly, which is why timing injections relative to meals, sleep, and exercise is often emphasized in research protocols.