Doses, Routes, and Half-Life Studied in the Sermorelin Literature

The short version

This page records the sermorelin dosage figures that appear in published studies — what researchers gave, to whom, by which route. It is not a how-to and contains no instructions for use. Quick orientation: in the children's study, the peptide was injected under the skin once a day; in the aging study, older men received it under the skin twice a day for two weeks; and the peptide clears from the blood fast — a plasma half-life of about 10-12 minutes — even though a single dose keeps growth hormone elevated for around three hours. That fast clearance is exactly why longer-lasting versions were later engineered.

Doses Studied in the Research Literature

The sermorelin dosage record is drawn from the trials, framed as what was administered to which population by which route — never as a recommendation. In the pediatric growth hormone-deficiency efficacy study, GHRH(1-29) was given at 30 mcg/kg/day subcutaneously at bedtime ^[1]. In the aging research in older men, GHRH(1-29) was administered at 0.5 mg and 1 mg subcutaneously twice daily for 14 days, producing dose-related growth hormone and IGF-1 increases ^[2]. In a pharmacokinetic study in 30 healthy men, intravenous doses of 0.25-2 mcg/kg elicited growth hormone release, with maximal release at 1-2 mcg/kg ^[3]. A diagnostic GHRH stimulation test historically used a single intravenous bolus (commonly around 1 mcg/kg) to probe pituitary growth hormone reserve.

These are doses studied in the research, summarized for completeness of the record. No human dosing instruction is given or implied.

Routes Studied

Three routes appear in the literature. Subcutaneous injection is the primary route in the efficacy and aging studies ^[1][2]. Intravenous administration was used in diagnostic and pharmacokinetic work ^[3]. Intranasal administration was examined historically, but bioavailability was only about 3-5% ^[3] — a low figure that helps explain why research-user communities widely criticize oral, sublingual, and troche "sermorelin" formulations as ineffective: peptides are degraded in the gut and poorly absorbed across mucosa.

Half-Life and Pharmacokinetics

Sermorelin's half-life and pharmacokinetics are the defining structural fact of the molecule. GHRH(1-29) has a short plasma half-life on the order of about 10-12 minutes after intravenous administration and is rapidly eliminated, yet a single dose elevates serum growth hormone for roughly three hours ^[3]. That elevation despite rapid clearance reflects the kinetics of pituitary stimulation rather than persistence of the peptide itself.

The native peptide's brevity is what motivated longer-acting analogs. Substituting D-Ala at position 2 of GHRH(1-29)NH2 and adding the DAC (drug affinity complex) technology — a maleimide group that binds serum albumin to extend half-life — is the structure-activity basis behind longer-acting GHRH analogs such as CJC-1295 with DAC. That contrast is the subject of the sermorelin vs CJC-1295 comparison.

Why timing appears in the dosing studies

The dosing record repeatedly notes time of day, not just amount. The pediatric efficacy study administered GHRH(1-29) at bedtime ^[1], and aging and cognition research has favored nocturnal dosing ^[6]. The physiologic reason is that endogenous growth hormone is released in pulses, especially during slow-wave sleep, and sleep-endocrine responses to GHRH are time-of-administration dependent ^[8]. Pulsatile delivery also preserves growth hormone responsiveness relative to continuous infusion ^[9], which is why intermittent dosing — rather than a steady drip — is the pattern that appears across the literature. This explains a feature of the study protocols; it is not a schedule to follow.

Formulation and Stability Notes

Lyophilized sermorelin acetate is reconstituted with sterile diluent and, once reconstituted, is typically refrigerated. Aqueous peptide solutions are susceptible to degradation, which is why GHRH(1-29) is supplied as a lyophilized powder. Compounded preparations are prepared under USP <797> sterile-compounding standards. These are handling characteristics documented for the peptide, not a preparation or administration protocol.