# Ipamorelin Dosage in Preclinical Studies — Dose Ranges, Routes, and Pharmacokinetics

> Ipamorelin dosage in preclinical research spans 1–100 µg/kg in GH-release studies to 100 µg/kg SC three times daily in three-month bone studies. Plasma half-life ~2 hours. Research context only.

## Ipamorelin Dosage in Preclinical Studies

Ipamorelin research spans four dose contexts, each corresponding to a different research area.

**GH-release selectivity studies (Raun et al. 1998):** Doses of 1–100 µg/kg administered intravenously to rats for acute GH-pulse measurements [1]. At 100 µg/kg IV (>200-fold the GH-releasing ED₅₀), ACTH and cortisol remained unchanged [1].

**Bone biology studies:** Johansen et al. 1999 used three dose levels subcutaneously [3]. Andersen et al. 2001 used 100 µg/kg SC three times daily for three months in adult female rats [4].

**GI motility studies (Venkova et al. 2009):** Doses ranging 0.01–1 mg/kg IV bolus in male rats [5].

**Phase 2 clinical trial (NCT00672074):** IV infusion in post-surgical human patients [15]. Specific dose levels not published.

## Ipamorelin Half-Life and Pharmacokinetics

Plasma half-life: approximately 2 hours in rat pharmacokinetic model data. GH pulse peak at 15–40 minutes post-injection SC. GH returns to baseline within approximately 3 hours [2].

Systemic clearance is approximately 5-fold lower than GHRP-6 [2]. Intranasal bioavailability: approximately 20% relative to IV [2]. Excretion predominantly urinary: 60–80% of administered dose recoverable intact from urine and bile. Free-acid metabolites persist in urine after the parent compound clears — the basis for the WADA detection window established in Semenistaya et al. 2015 [9].

## Ipamorelin Dosing Frequency in Preclinical Protocols

GH-pulse selectivity studies are acute (single IV dose) [1]. Bone elongation studies: subcutaneous, three-month treatment window [3]. Andersen 2001 bone protection study: three-times-daily SC injection for three months — most intensive preclinical frequency protocol [4]. GI motility studies: single IV bolus or repetitive IV dosing [5].

How long for Ipamorelin to work in animal models: GH pulse onset 15–30 minutes post-injection [2]; bowel motility changes within hours in surgical models [5]; bone formation changes over 3-month treatment windows [4].

## Routes of Administration Studied

**Intravenous (IV):** Acute pharmacology and GI motility studies [1, 5, 6, 15].

**Subcutaneous (SC):** Bone studies and somatotroph plasticity studies [3, 4, 7]. Each SC injection produces one discrete GH pulse with peak at 15–40 min and return to baseline at ~3 h [2].

**Intranasal:** Characterized by Johansen et al. for bioavailability; approximately 20% systemic exposure relative to IV [2].

Human clinical pharmacokinetics for any route have not been formally published. All half-life and clearance figures above are rodent data.

## References

[1] Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561.
[2] Johansen PB, et al. Pharmacokinetic evaluation of ipamorelin. Xenobiotica. 1998;28(12):1235-1248.
[3] Johansen PB, et al. Ipamorelin induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106-113.
[4] Andersen NB, et al. Ipamorelin counteracts glucocorticoid-induced decrease in bone formation. Growth Horm IGF Res. 2001;11(5):266-272.
[5] Venkova K, et al. Efficacy of ipamorelin in a rodent model of postoperative ileus. J Pharmacol Exp Ther. 2009;329(3):1110-1116.
[6] Greenwood-Van Meerveld B, et al. Efficacy of ipamorelin on gastric dysmotility. J Exp Pharmacol. 2012;4:149-155.
[7] Jiménez-Reina L, et al. Influence of chronic ipamorelin treatment in young female rats. Histol Histopathol. 2002;17(3):707-714.
[9] Semenistaya E, et al. GHRP metabolites in human urine after nasal administration. Drug Test Anal. 2015;7(11-12):1014-1019.
[15] Helsinn Therapeutics. NCT00672074. ClinicalTrials.gov. 2017.

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A grid-indexed literature digest on Ipamorelin — nineteen primary findings, clean GH pulses, and no commercial position on any of them.