Half-Life

In pharmacology, half-life (t1/2) refers to the time required for the plasma concentration of a drug or peptide to decrease by 50% through the combined effects of distribution, metabolism, and excretion. This parameter is critical for determining dosing frequency, steady-state concentrations, and the duration of pharmacological effect. Native peptide hormones often have very short half-lives (GLP-1: ~2 minutes, GHRH: ~7 minutes, ghrelin: ~30 minutes) due to rapid enzymatic degradation, which drives the development of modified analogues with extended half-lives. For example, semaglutide's C18 fatty diacid acylation extends its half-life to approximately 7 days by promoting albumin binding, and CJC-1295 DAC achieves a half-life of 6-8 days through a similar strategy. ORYN's pen system delivers peptides subcutaneously, where they form a depot that provides controlled absorption.