MUSCLE, GROWTH & RECOVERY SLEEP, STRESS & CALM

Ipamorelin

The most selective growth-hormone secretagogue in its class—studied for clean GH pulses without the cortisol or prolactin spikes of older compounds.

Ipamorelin is a five-amino-acid peptide that triggers the body's own growth-hormone release through the ghrelin receptor (GHS-R1a). It is regarded as the most selective compound in the GH-secretagogue class: in the original head-to-head pharmacology it released growth hormone without raising cortisol, prolactin, or other pituitary hormones. It reached Phase 2 human trials and remains one of the most widely used GH-axis research peptides—studied alone or paired with a GHRH analog acting on the complementary receptor.

GHS-R1a AgonistSelective GH PulseRecoveryDeep Sleep

Why BLP features Ipamorelin

Included because its selectivity is unusually well documented for a research peptide—head-to-head pharmacology showed a clean GH pulse with no ACTH, cortisol, or prolactin response—and it carries a Phase 2 clinical history plus one of the longest research-use track records in the GH-secretagogue class.

Mechanism

Binds the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus, triggering a natural pulse of the body's own growth hormone. Its half-life is roughly 2 hours.

Selectivity is its signature: in the original pharmacology (Raun et al., 1998), even doses far above the effective GH-releasing dose produced no ACTH or cortisol response—unlike the older secretagogues GHRP-2 and GHRP-6—and no effect on FSH, LH, prolactin, or TSH.

Works with the body's pulsatile release rhythm rather than overriding it. In research it is frequently paired with a short-acting GHRH analog, which amplifies the same pulse through a different receptor.

WHAT THE RESEARCH MEASURED

Research findings

Findings describe study outcomes, not expected personal results.

Human research findings

Human studies confirmed dose-dependent growth-hormone release. Ipamorelin reached Phase 2 clinical trials (for postoperative ileus, a gut-motility indication); development was discontinued after the trial missed its primary motility endpoint—an efficacy miss on that endpoint, not a GH-axis failure.
No controlled human trial exists for body-composition, recovery, or sleep outcomes with standalone Ipamorelin.
Reported research-use observations (not controlled endpoints): improved training recovery, deeper sleep, and gradual body-composition change, with IGF-1 elevation in the physiological range.

Preclinical findings

Selectivity characterized in classic receptor pharmacology: full growth-hormone release with no cortisol or prolactin response at high multiples of the effective dose.
Animal studies reported body-weight and growth gains consistent with GH-axis activation.

Regulatory status

Investigational; clinical development (for postoperative ileus) was discontinued after Phase 2. Offered strictly for laboratory and research use and is not FDA-approved.

Related research

Ipamorelin/CJC-1295 CJC-1295 (no DAC)Tesamorelin Evidence Framework Research Library