Encyclopedia entry

Peptide half-life

Half-life is the time it takes for the concentration of a compound in the body to fall by half. Across peptides commonly discussed in research, half-life varies from a few minutes (native Sermorelin) to over a week (semaglutide). The variation is driven by amino acid sequence, structural modifications, and any added albumin-binding groups.

Typical half-lives across categories

• · Native GHRH and Sermorelin: 10 to 20 minutes.
• · Tesamorelin: approximately 30 minutes (N-terminal stabilisation).
• · CJC-1295 without DAC: approximately 30 minutes.
• · CJC-1295 with DAC: 8+ days (DAC binds albumin).
• · Ipamorelin: approximately 2 hours.
• · BPC-157: approximately 4 to 6 hours (oral form).
• · Liraglutide (Saxenda): approximately 13 hours.
• · Semaglutide (Wegovy, Ozempic): approximately 7 days.
• · Tirzepatide (Mounjaro): approximately 5 days.

Why half-life matters

Half-life sets the practical dosing frequency. A 13-hour half-life means daily injection; a 7-day half-life means weekly injection. For weight-management medications, the move from daily Saxenda to weekly Wegovy was a major adherence improvement driven entirely by the half-life difference between liraglutide and semaglutide.

How modifications extend half-life

• · N-terminal or C-terminal modifications: resist enzymatic degradation by aminopeptidases or carboxypeptidases. Tesamorelin uses this approach.
• · Albumin-binding moieties: attach a fatty acid or DAC linker that binds circulating albumin, dramatically extending half-life. Liraglutide and semaglutide both use this approach.
• · Backbone substitutions: non-natural amino acids in the middle of the chain resist proteolysis. Used in some experimental peptides.
• · PEGylation: polyethylene glycol attached to extend circulation time. Common in some biotech but rare in current weight-management drugs.

Related: SPPS · research peptides hub.