Ipamorelin is a pentapeptide growth hormone secretagogue and a growth hormone secretagogue receptor 1A agonist. Developed by Novo Nordisk, it binds the anterior pituitary somatotrope with high affinity and high selectivity, and it carries GHRH-like selectivity that also engages hypothalamic regulation. An alpha amino isobutyric acid modification confers protease resistance, giving it a half-life of roughly two hours. This lesson covers its mechanism, the available evidence, and how clinicians approach its use.

Mechanistically, receptor binding activates a Gq pathway through PLC, IP3, and DAG, mobilizing intracellular calcium and triggering exocytosis of growth hormone from somatotrope secretory vesicles. The release stays pulsatile and preserves normal negative feedback through somatostatin, so it does not override hypothalamic regulation. The defining feature is selectivity: meaningful GH release without ACTH, cortisol, prolactin, FSH, LH, or TSH effects, with minimal appetite stimulation.

The lesson also clarifies a naming discrepancy: much of what compounding pharmacies label CJC-1295 is modified GRF 1-29 without the DAC modification, which has a much shorter half-life than DAC-modified CJC-1295.

For monitoring, the discussion points to baseline labs including IGF-1, fasting glucose, hemoglobin A1c, lipids, CBC, and CMP, with IGF-1 rechecked around four to six weeks and annually. Watch for fluid retention, arthralgias, carpal tunnel signs, and glucose changes. Active malignancy, pregnancy, and lactation are noted as contraindications, and informed consent for off-label investigational use is emphasized.

Key clinical points

• Selective profile: potent GH stimulation that spares cortisol, ACTH, and prolactin, which distinguishes it from GHRP-6, GHRP-2, and Hexarelin.
• Pharmacokinetics: roughly two-hour half-life, peak response near 40 minutes, primarily renal excretion with most of the peptide recovered intact in urine. It is detectable in urine and prohibited under WADA.
• Preclinical signals: animal studies noted dose-dependent bone growth, increased bone mineral content, counteraction of glucocorticoid-induced bone and muscle loss, and prokinetic GI effects. Human body composition data remain limited.
• Clinical trials: a phase two postoperative ileus trial showed good safety and tolerability but did not meet its primary endpoints for gastric motility.
• Dosing discussed: subcutaneous is preferred, commonly around 100 micrograms, one to three times daily, often at bedtime to align with nighttime GH pulses. Cycled schedules and combination with a GHRH analog such as CJC-1295 were reviewed for dual receptor activation.