IPAMORELIN 10MG

Ipamorelin activates the GHS-R1a (ghrelin receptor) on pituitary somatotroph cells with an in vitro EC₅₀ of 1.3 ± 0.4 nmol/L and in vivo ED₅₀ of 2.3 nmol/kg (swine). Binding triggers phospholipase C (PLC) activation via Gα₁₁/q → IP3 → intracellular Ca²⁺ release → GH vesicle exocytosis — a pathway distinct from GHRH's cAMP signaling.[1][2]

Receptor & Signaling Profile

Target	Action	Downstream Effect
GHS-R1a (Ghrelin Receptor)	Selective agonist	PLC → IP3 → Ca²⁺ → GH vesicle exocytosis
cAMP (Synergistic)	Enhances pre-stimulated adenylyl cyclase	Synergistic GH release when combined with GHRH
Enteric Cholinergic Neurons	Activates excitatory neurons (atropine/TTX-sensitive)	Accelerates gastric motility and emptying

Ipamorelin's selectivity is exceptional: it does NOT stimulate ACTH, cortisol, FSH, LH, prolactin, or TSH — even at doses 200× the ED₅₀. Additionally, chronic administration does not desensitize somatotrophs, unlike GHRH which induces homologous down-regulation.[1][7]

In humans, Ipamorelin exhibits linear pharmacokinetics with a T½ of ~2 hours, SC₅₀ of 214 nmol/L, and triggers a single episodic GH burst peaking at 0.67 hours post-administration.[2]

At the cellular level, the PLC/Ca²⁺ cascade engaged by ipamorelin diverges from the cAMP/PKA cascade activated by GHRH. This divergence is mechanistically important: when both receptor systems are co-stimulated in research models, somatotrophs release more GH than either pathway can produce alone, an effect attributed to the convergent activation of multiple second-messenger systems on the same secretory cell.[1][2] The PLC pathway also engages diacylglycerol/PKC signaling that contributes to GH gene transcription via CREB phosphorylation, supporting sustained somatotroph output during repeat dosing.[7]

Outside the pituitary, ipamorelin engages GHS-R1a expressed on enteric cholinergic neurons, where it activates atropine- and tetrodotoxin-sensitive excitatory pathways that accelerate gastric and colonic transit — the mechanistic basis for its evaluation in postoperative ileus models.[4][5] The compound also binds peripheral ghrelin receptors on enteric afferent neurons, attenuating visceromotor responses to noxious distension in rat models — an effect blocked by selective ghrelin receptor antagonists, confirming receptor specificity.[17]

vs. Related Compounds

Feature	Ipamorelin	GHRP-6 / GHRP-2	GHRH
Selectivity	HIGH — GH only	LOW — GH + ACTH + cortisol + prolactin	Selective for GH
Desensitization	NO	Partial	YES (homologous)
Primary Signaling	PLC / Ca²⁺	PLC / Ca²⁺	cAMP
Half-Life (Human)	~2 hours	Shorter (5× faster clearance)	Minutes

Ipamorelin research spans 8+ indication categories across GH physiology, GI motility, musculoskeletal biology, and pain. The compound is widely deployed in preclinical pharmacology as a selective GHS-R1a probe, and historical clinical evaluation has provided human pharmacokinetic and safety data that inform downstream investigational use.[1][2]

1. Selective GH Secretion — Pulsatile GH release without ACTH/cortisol effects; potency comparable to GHRP-6 but with GHRH-like selectivity. Used as the prototypical selective GHS in receptor pharmacology research.[1]
2. Postoperative Ileus (POI) — Accelerates gastric emptying via GHS-R1a on cholinergic neurons; reduces stomach retention to <25% (vs 78% vehicle) in rodent models. Phase II clinical trial in bowel-resection subjects failed to reach significance (median meal tolerance 25.3h vs 32.6h placebo, p=0.15).[4][6]
3. Bone Growth & Metabolism — Dose-dependent longitudinal bone growth in adult female rats (42→52 µm/day, p<0.0001) at 18–450 µg/day SC over 15 days; increased tibial and vertebral bone mineral content in long-term studies.[3][8]
4. Glucocorticoid-Induced Catabolism — In rats receiving methylprednisolone, ipamorelin (100 µg/kg SC TID × 3 months) increased periosteal bone formation rate 4-fold and increased maximum tetanic muscle tension, suggesting an osteo-anabolic and myogenic role in steroid-myopathy research models.[12]
5. Body Composition & Adiposity — In GH-deficient (lit/lit) mice, 250 µg/kg SC BID for 2–9 weeks increased body weight by 15–17% and increased adiposity even in the absence of GH signaling, demonstrating GH-independent adipogenic effects mediated by central ghrelin pathways.[9]
6. Insulin Secretion — In normal and diabetic rat pancreatic tissue (10⁻¹² to 10⁻⁶ M in vitro), ipamorelin produced significant insulin release (p<0.04) via calcium channel activation and adrenergic receptor pathways, supporting use as a tool molecule in pancreatic islet research.[10]
7. Pain Modulation / Nociception — In rat visceral hypersensitivity models, 0.01–1.0 mg/kg IV produced dose-dependent reductions in visceromotor response that were blocked by selective ghrelin receptor antagonists, confirming peripheral GHS-R1a involvement in nociceptive signaling.[17]
8. Cancer Cachexia / Emesis — In ferrets receiving cisplatin chemotherapy, ipamorelin inhibited cisplatin-induced weight loss, confirming activity in a non-rodent wasting model and establishing a research basis for ghrelin-mimetic interventions in chemotherapy-induced cachexia paradigms.[14]

Comparative research with structurally related compounds — including sermorelin, CJC-1295, and tesamorelin — has examined whether GHS-R1a vs GHRH-receptor stimulation produce different downstream metabolic, bone, and body-composition signatures. Combined regimens (ipamorelin + GHRH analog) consistently produce GH release exceeding either agent alone in research models, reflecting convergent activation of PLC/Ca²⁺ and cAMP/PKA cascades on shared somatotroph pools.[1][15]