# Ipamorelin Dosage — Research Protocols, Pharmacokinetics, and Biomarker Notes

> Ipamorelin dosage protocols from preclinical and clinical research — doses, routes, timing rationale, and pharmacokinetic data as documented in the published literature.

## Research Context

Ipamorelin is a research compound, not an approved drug. All dosing data on this page is drawn from published animal studies and the one Phase 2 human clinical trial (NCT00672074). This page summarizes the doses administered in those studies, the routes used, and the schedules reported. It does not recommend doses for human use.

The compound's entire ipamorelin dosage literature derives from rodent (rat, mouse), swine, and one human IV trial dataset. Subcutaneous administration — the route most frequently discussed in practice — has been studied in rats but not pharmacokinetically characterized in humans. Extrapolation from rat IV data to human subcutaneous administration involves substantial uncertainty.

## Ipamorelin Half-Life and Dosing Frequency

Johansen et al. (1998, PMID 9879640) characterized the pharmacokinetics of ipamorelin and related peptides in male rats following intravenous bolus administration. Plasma concentration declined biexponentially. Systemic clearance was approximately 5-fold lower than GHRP-6 under the same conditions. Between 60–80% of the administered dose was recoverable from bile and urine as intact peptide, indicating moderate metabolic stability relative to earlier GHRPs — attributable to the non-natural amino acid residues (Aib, D-2-Nal, D-Phe) that confer protease resistance [9].

Intranasal bioavailability was approximately 20% in the rat IV-to-intranasal comparison in the same study [9]. No subcutaneous bioavailability figure for ipamorelin has been published in the peer-reviewed literature.

The biexponential plasma decay and the pulsatile GH-release profile together underpin the multiple-injection-per-day approach seen in published rodent protocols — the short duration of each GH pulse is consistent with the premise that repeated dosing is required to sustain downstream IGF-1 elevation over a multi-week study [3][4][8].

Human pharmacokinetic data for subcutaneous ipamorelin does not exist in the published literature. The ipamorelin half-life context above is rat IV data; any application to human subcutaneous protocols involves extrapolation not supported by published human PK studies.

## Published Research Dose Ranges

The following doses appear in the published peer-reviewed record. All are research contexts, not clinical recommendations.

**Raun et al. 1998** (rat and swine, IV): 2.3–80 nmol/kg IV to establish dose-response for GH release and selectivity. EC50 in vitro ~1.3 nmol/L in primary pituitary cell culture [1].

**Johansen et al. 1999** (female Sprague-Dawley rat, SC): 18, 90, 450 µg/day administered via subcutaneous injection three times daily for 15 days to assess longitudinal bone growth rate [3].

**Svensson et al. 2000** (female Sprague-Dawley rat, SC osmotic minipump): 0.5 mg/kg/day for 12 weeks via subcutaneous osmotic minipump (continuous delivery), measuring bone mineral content and body composition by DXA [5].

**Andersen et al. 2001** (female Wistar rat, SC): 100 µg/kg three times daily via subcutaneous injection for 3 months, alongside methylprednisolone 9 mg/kg/day, to evaluate periosteal bone formation in a glucocorticoid-suppression model [4].

**Malmlöf et al. 1999** (female Wistar rat, IV): 0.4–1.6 mg/kg/day divided over four daily intravenous doses in a glucocorticoid co-treatment model [8].

**Venkova et al. 2009** (male Sprague-Dawley rat, IV): 0.01, 0.1, 1 mg/kg single IV doses for GI motility; 0.1 or 1 mg/kg × 4 doses/day at 3-hour intervals for repetitive efficacy in postoperative ileus model [6].

**NCT00672074 Phase 2 trial** (human, IV): 0.03 mg/kg intravenous infusion twice daily for up to 7 days in bowel-resection patients [11].

## Routes of Administration in the Published Literature

Three routes have been documented in published ipamorelin research:

**Intravenous** — the primary route in the Raun 1998 selectivity paper, the Malmlöf 1999 glucocorticoid model, the Venkova 2009 GI ileus model, and the NCT00672074 Phase 2 human trial. Most acute pharmacokinetic and GH-release characterization data uses IV administration [1][6][8][11].

**Subcutaneous** — used in the Johansen 1999 bone growth study (three daily injections), the Andersen 2001 glucocorticoid bone model (three daily injections), and the Svensson 2000 bone mineral content study (osmotic minipump continuous delivery) [3][4][5]. The most common route in preclinical anabolic outcome studies.

**Intranasal** — approximately 20% bioavailability in male rats (Johansen et al. 1998), studied as a potential non-injection delivery option [9]. Not further evaluated in published outcome studies.

## References

[1] Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552–561. https://pubmed.ncbi.nlm.nih.gov/9849822/
[3] Johansen PB, et al. Ipamorelin induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106–113. https://pubmed.ncbi.nlm.nih.gov/10373343/
[4] Andersen NB, et al. Ipamorelin counteracts glucocorticoid-induced decrease in bone formation. Growth Horm IGF Res. 2001;11(5):266–272. https://pubmed.ncbi.nlm.nih.gov/11735244/
[5] Svensson J, et al. Ipamorelin and GHRP-6 increase bone mineral content in adult female rats. J Endocrinol. 2000;165(3):569–577. https://pubmed.ncbi.nlm.nih.gov/10828840/
[6] Venkova K, et al. Efficacy of ipamorelin in a rodent model of postoperative ileus. J Pharmacol Exp Ther. 2009;329(3):1110–1116. https://pubmed.ncbi.nlm.nih.gov/19289567/
[7] Jiménez-Reina L, et al. Chronic ipamorelin treatment in young female rats: somatotroph response in vitro. Histol Histopathol. 2002;17(3):707–714. https://pubmed.ncbi.nlm.nih.gov/12168778/
[8] Malmlöf K, et al. Methylprednisolone does not inhibit GH release after ipamorelin in rats. Growth Horm IGF Res. 1999;9(6):396–403. https://pubmed.ncbi.nlm.nih.gov/10629165/
[9] Johansen PB, et al. Pharmacokinetics of ipamorelin with emphasis on nasal absorption. Xenobiotica. 1998;28(11):1083–1091. https://pubmed.ncbi.nlm.nih.gov/9879640/
[11] Bochicchio GV, et al. Ipamorelin for management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014. https://link.springer.com/article/10.1007/s00384-014-2030-8

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A pastel-cloud reading of the ipamorelin literature — soft pulsatile pharmacology summarized from the peer-reviewed record, held by no clinic and sold by no one.