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Sermorelin

GHRH analog

Also known as: GHRH (1-29), GRF (1-29), Geref

Tier 2, Investigational, human data

Studied in registered human trials with published pharmacokinetic data, but not approved. Dosing outside a trial protocol has no established safety margin.

Half-life
4.3 minutes · human data · intravenous

Disappearance half-time 4.3 +/- 1.4 minutes after IV administration in normal men, with metabolic clearance 39.7 mL/kg/min. The frequently quoted "11-12 minutes" appears only in secondary sources; the measured primary value is ~4.3 min IV. No validated subcutaneous half-life was located. Intranasal bioavailability is only 3-5%.

Model a dosing schedule →
Dosing
No established dose

Weight-based, not fixed-mcg. In healthy men the minimal effective IV dose was 0.25 mcg/kg with maximal GH release at 1-2 mcg/kg IV. Absolute values left blank rather than back-calculated from an assumed body weight.

Frequency
Once daily at bedtime in the historical paediatric GHD indication
Timing
Bedtime dosing was used to align with endogenous nocturnal GH pulsatility.
Regulatory status
Formerly FDA approved (Geref, 1997, paediatric GH deficiency). Production ceased 2008 and approval was withdrawn in 2009, a 2013 Federal Register notice confirmed the withdrawal was NOT for reasons of safety or effectiveness. Currently available in the US only via 503A compounding with a prescription. Prohibited at all times under WADA section S2.
Evidence base
human clinical · confidence: medium
Safety

Historically the most common adverse event was injection-site reaction. Because sermorelin acts on the pituitary via the GHRH receptor, GH release remains subject to negative feedback and somatostatin tone, which limits supraphysiologic exposure relative to exogenous rhGH. Requires an intact pituitary to work at all. Marketed anti-ageing use is off-label and unsupported by the approved indication.