Ipamorelin half-life & pharmacokinetics

Reported half-life

~2 hours plasma half-life in humans (Raun et al., Eur J Endocrinol, 1998). Single subcutaneous administration produces a discrete GH pulse with peak GH at approximately 30 minutes post-injection and return to baseline by 2-3 hours. Pharmacokinetics support twice- or thrice-daily dosing for pulsatile GH-release protocols.

The half-life and pharmacokinetic profile of Ipamorelin 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)
• Intramuscular injection (research)
• Intravenous bolus (research, pre-clinical only)

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 pentapeptide GHRP; selective ghrelin-receptor (GHSR-1a) agonist with high GH/non-GH-pituitary-hormone selectivity ratio.

Mechanism context

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

Ipamorelin is a 5-amino-acid synthetic peptide (Aib-His-D-2-Nal-D-Phe-Lys-NH₂) designed by the Novo Nordisk group through systematic modification of the GHRP-6 template to maximise growth-hormone-releasing activity while minimising off-target effects on other anterior-pituitary hormones. The four non-standard amino-acid features — α-aminoisobutyric acid (Aib) at position 1, D-2-naphthylalanine (D-2-Nal) at position 3, D-phenylalanine at position 4, and C-terminal amidation — confer protease resistance, optimised receptor binding geometry, and the high selectivity profile that defines its pharmacological niche.

See the full Ipamorelin 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.