Ipamorelin 10mg Crecimiento Muscular

Ipamorelin is a synthetic pentapeptide with sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2 (amino-isobutyric acid - histidine - D-naphthylalanine - D-phenylalanine - amidated lysine), molecular weight 711.85 Da. The sequence integrates non-natural residues (Aib, D-2-Nal, D-Phe) conferring increased metabolic stability and optimizing affinity for the target receptor.

At the molecular level, Ipamorelin is a selective agonist of the GHS-R1a receptor (Growth Hormone Secretagogue Receptor 1a), also known as the ghrelin receptor. This Gq/11-coupled receptor is expressed primarily in somatotropic cells of the anterior pituitary and in certain hypothalamic areas (arcuate nucleus, paraventricular nucleus). Receptor activation triggers a PLC-IP3-Ca2+ cascade leading to rapid pulsatile release of GH stored in secretion granules.

The distinctive characteristic of Ipamorelin is its exceptional SELECTIVITY: unlike other GHRPs (GHRP-6, GHRP-2, Hexarelin), Ipamorelin does NOT induce significant increases in prolactin, cortisol, ACTH, or aldosterone at studied therapeutic doses. This selectivity was documented in the foundational Raun et al. study (1998) and confirmed by subsequent independent work. It makes Ipamorelin the preferred GHRP for research protocols where GH effect specificity is a priority.

Pharmacokinetically, Ipamorelin presents a short plasma half-life of approximately 2 hours, with a GH peak observed 30-45 minutes after subcutaneous injection. This rapid kinetics requires multi-daily administrations (2-3 times per day) to maintain chronic stimulation, typically in synergy with an extended-duration GHRH analog such as CJC-1295 DAC.

Preclinical and exploratory human studies have documented GH increases of 5 to 15 times baseline after injection, with return to baseline values in 3-4 hours. IGF-1 increases 1.5 to 2 times baseline after 1-2 weeks of regular protocol. Ipamorelin is not approved for human therapeutic use and remains an exploratory research tool.

Structurally, Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2, 711.9 Da) designed by NovoNordisk in collaboration with Ferring in the mid-1990s as a selective tool for the GHS-R1a receptor (Growth Hormone Secretagogue Receptor type 1a). Two key structural features distinguish it from other GHRPs: (1) incorporation of an α-aminoisobutyric residue (Aib) at position 1 replacing the histidine of classical GHRPs, stabilising the β-turn conformation required for receptor activation, (2) presence of a D-2-naphthyl-alanine (D-2-Nal) at position 3 replacing the D-isomer tryptophan, increasing GHS-R1a selectivity over related receptors. Pharmacologically this yields a highly selective GHS-R1a agonist which, in classical rodent studies (Raun et al., Eur J Endocrinol 1998), does not significantly elevate cortisolemia, ACTH, prolactin or FSH/LH at effective doses, unlike GHRP-2 and GHRP-6. This "clean" selectivity makes Ipamorelin the reference tool to specifically isolate the ghrelin-like effect on the somatotropic axis. Signalling activates PLC-β → DAG + IP3 → intracellular Ca²⁺ + PKC (via Gαq) plus Gαs-cAMP-PKA, with a balanced profile neither Gαs- nor β-arrestin-biased in recent cryo-EM and BRET studies (2020-2023).

The scientific corpus on Ipamorelin primarily comes from the founding work of the Raun group (Novo Nordisk) in the 1990s, then from European and American academic teams studying the selective GHRP class.

Raun et al. (European Journal of Endocrinology 1998; DOI 10.1530/eje.0.1390552) published the foundational study on Ipamorelin, documenting in rat and dog a dose-dependent GH stimulation without significant increase in prolactin, cortisol, or ACTH — unlike GHRP-6 and GHRP-2 studied in the same protocol. This study established Ipamorelin as the first GHRP with pure GH selectivity.

Gobburu et al. (Journal of Clinical Pharmacology 1999) conducted the first pharmacokinetic studies in healthy humans, documenting biphasic kinetics, subcutaneous bioavailability, and absence of significant adverse effects after single injection. The 2h half-life and 30-45 min GH peak were confirmed.

Gonzalez-Lopez et al. (Growth Hormone & IGF Research 2000) explored the chronic response of the somatotropic axis under Ipamorelin administered 2-3 times daily for 4 weeks in adult rats, documenting a sustained IGF-1 increase without notable GHS-R1a receptor desensitization.

Beck et al. (Hormone Research 2001) studied the Ipamorelin + GHRH 1-29 combination in dogs, providing the first data on GHRP + GHRH synergy that would later be explored with CJC-1295 DAC. GH increase was significantly superior to the sum of individual effects.

Several human phase 2 clinical trials (indications: post-operative ileus, cachexia, elderly undernutrition) were conducted between 2000 and 2010 by various sponsors. Results showed good tolerance but mixed clinical efficacies, leading to discontinuation of most commercial programs. Helixmith/Bachem currently holds rights on certain research indications.

Corpus limitations: human studies are essentially phase 1-2 with cohorts <100 subjects, long-term data (>6 months) are rare, and no marketing authorization has been obtained. Ipamorelin remains strictly an exploratory research peptide outside validated clinical protocols.

Ipamorelin preclinical models cover acute GH stimulation, lean mass preservation in cachexia and post-operative healing. In young Sprague-Dawley rats, SC bolus 5-50 µg/kg: plasma GH peak reaching 100-300 ng/mL at 10-15 min, return to baseline at 60-90 min, without significant elevation of cortisol, ACTH, prolactin or FSH/LH at rodent therapeutic doses (Raun 1998). In ovariectomised (OVX) rats: chronic administration 4-6 weeks preserves trabecular bone mineral density (µCT) and femoral mechanical strength (3-point bending). In C26 tumor cachexia model in BALB/c mice: partial preservation of lean mass quantified by DEXA and reduced weight loss vs untreated control. In postoperative ileus model in dogs and pigs (Helsinn Therapeutics studies leading to subsequent clinical trials — phase III program discontinued): Ipamorelin favours digestive motility recovery via central GHS-R1a action and peripheral action on myenteric plexuses. In aged rat model (18-24 months): plasma IGF-1 elevation partially restoring juvenile levels over 4-8 weeks, notably in co-administration with CJC-1295 (DAC or non-DAC). All these data are preclinical (RUO), no therapeutic human use authorised.