Sermorelin half-life & pharmacokinetics

Reported half-life

Approximately 5-12 minutes plasma half-life — the shortest of the GHRH-analogue class, reflecting rapid DPP-4-mediated cleavage of the N-terminal His-Ala bond. Each subcutaneous administration produces a transient GH pulse with peak GH at 30-45 minutes and return to baseline by 90-120 minutes.

The half-life and pharmacokinetic profile of Sermorelin reported above is drawn from the published pre-clinical literature. Plasma half-life describes the time taken for the circulating concentration to fall by half after a single dose; tissue half-life — which may be longer for peptides retained in specific organs or matrices — is a distinct and often more relevant parameter for healing research, where the duration of exposure at the injury site matters more than the systemic exposure profile.

Routes of administration studied

• Subcutaneous injection (research; standard route)
• Intravenous bolus (research; faster onset)
• Intramuscular injection (research, less common)

Different routes produce materially different pharmacokinetic profiles for the same peptide. Subcutaneous administration generally produces flatter, more sustained plasma profiles than intravenous bolus dosing; intraperitoneal administration (common in rodent models) is not directly translatable to human routes; oral administration faces the additional challenge of luminal and brush-border peptidase degradation, which is why most research peptides have very low oral bioavailability without protective formulation.

Drug class

Synthetic GHRH (1-29) — the biologically active N-terminal fragment of native human GHRH; unmodified amino-acid sequence with no protease-resistance substitutions.

Mechanism context

Half-life interpretation depends on the underlying mechanism. Sermorelin acts as follows:

Sermorelin is the synthetic 29-amino-acid N-terminal fragment of native human GHRH (the full-length molecule is 44 amino acids). The first 29 residues retain full GHRH-receptor agonism — the C-terminal extension of native GHRH 30-44 is not required for receptor binding or pituitary signalling. This makes sermorelin the prototype GHRH analogue and the foundation from which all modified GHRH-class compounds (CJC-1295, tesamorelin) have been derived.

See the full Sermorelin research profile for the complete mechanism summary, history, study citations, and references.

Practical considerations

Short plasma half-life does not necessarily mean short duration of biological effect. Many peptides — including BPC-157, GHK-Cu, and the thymosin-derived compounds — exhibit tissue retention or mechanistic effects (gene expression, signalling cascades) that outlast plasma exposure by hours to days. The pharmacological half-life and the biological-effect half-life are distinct parameters that must both be specified in any rigorous research design. Repeated-dose protocols should account for accumulation only where tissue half-life is genuinely long; for most peptides with short plasma half-life and rapid degradation, accumulation is not a practical concern.

For dose ranges in published research, see the dosing reference page. For reconstitution guidance, see the reconstitution reference page.