Compound Guide• 7 min read
Tesamorelin: GHRH Analog Mechanism, Visceral Fat Studies & Research Dosing
Tesamorelin is a synthetic 44-amino-acid analog of growth-hormone-releasing hormone (GHRH) with a trans-3-hexenoic acid modification that resists enzymatic breakdown. It is the only GHRH peptide approved by the FDA as a finished drug product (Egrifta) and is sold here strictly as a research reagent.
What tesamorelin is
Tesamorelin is GHRH(1-44) with an N-terminal trans-3-hexenoic acid group. The modification extends its plasma half-life enough to support once-daily research dosing.
Unlike exogenous growth hormone, tesamorelin acts upstream — at the pituitary — to stimulate the body's natural pulsatile release of endogenous growth hormone. This preserves negative-feedback regulation by IGF-1 and somatostatin.
Mechanism of action
Tesamorelin binds the GHRH receptor on somatotroph cells of the anterior pituitary, triggering cAMP-mediated release of growth hormone. The resulting GH pulses raise IGF-1 production in the liver and modulate lipolysis in visceral adipose tissue.
Clinical-trial findings
Phase 3 studies in HIV-associated lipodystrophy reported a roughly 15 % reduction in visceral adipose tissue (VAT) after 26 weeks of daily 2 mg subcutaneous administration, with reciprocal increases in IGF-1. A subsequent NASH/MASH program is studying whether the same VAT reduction translates to reduced hepatic steatosis.
Research dosing in the literature
The protocol most widely cited in research papers is 2 mg subcutaneously once daily. Vials carried in the research market are typically 5 mg or 10 mg lyophilized, reconstituted at 2 mg/mL in bacteriostatic water for laboratory study designs.
Storage
Lyophilized tesamorelin is stable for 18+ months at −20 °C. Reconstituted vials should be refrigerated at 2–8 °C and used within 14 days; GHRH analogs are particularly sensitive to repeated freeze/thaw cycles.
FAQ
How is tesamorelin different from sermorelin or CJC-1295?
All three are GHRH-pathway peptides. Sermorelin is GHRH(1-29) with a short half-life. CJC-1295 (DAC) carries a DAC linker that pushes half-life to days. Tesamorelin sits between them, with a hexenoic-acid stabilization on the full 1-44 sequence.
Is tesamorelin the same as growth hormone?
No. Tesamorelin prompts the pituitary to secrete the body's own GH in its natural pulsatile pattern; exogenous GH bypasses this regulation entirely.