Tesamorelin

Tesamorelin is a 44-amino-acid analog of human growth-hormone-releasing hormone (GHRH) with a trans-3-hexenoyl modification on the N-terminal Tyr¹ that confers resistance to dipeptidyl-aminopeptidase-IV degradation ([Ferdinandi et al., *Basic Clin Pharmacol Toxicol* 2007, 100:49–58](https://doi.org/10.1111/j.1742-7843.2007.00008.x)). Once injected subcutaneously, it binds the GHRH receptor on pituitary somatotrophs and triggers pulsatile growth hormone release, which in turn drives IGF-1 production in the liver. Plasma half-life is roughly 26 to 38 minutes — short enough that GH and IGF-1 stay broadly within their normal pulsatile pattern rather than being chronically elevated, which is the safety story the FDA reviewed.

Tesamorelin is the credibility flagship of the GH-axis class. It is the only peptide on this site with an actual FDA approval (Egrifta and Egrifta SV, indicated for excess visceral fat in adults with HIV-associated lipodystrophy) and the only one whose evidence base includes large multicenter Phase III RCTs in humans. The pivotal trial (Falutz et al., NEJM 2007) randomized 412 patients with HIV-associated abdominal fat accumulation to 2 mg daily subcutaneous tesamorelin or placebo for 26 weeks. Visceral adipose tissue dropped by 15.2% in the tesamorelin arm versus a 5.0% increase in placebo; triglycerides fell by ~50 mg/dL while rising in placebo; IGF-1 rose by ~81% above baseline. Glycemic measures did not change significantly over the trial period. That credibility comes with a sharp boundary. The published efficacy is in HIV-associated lipodystrophy, not in non-HIV populations seeking general body recomposition. The visceral-fat reduction is real but modest in absolute terms and reverses when treatment stops. Off-label use of tesamorelin in non-indicated populations is widespread in longevity and biohacker circles, but the controlled human evidence outside HIV is thin — most of what is publicly available comes from small academic studies or mechanistic extrapolation. Legitimate access also costs in the thousands of dollars per month, which is part of why compounded versions exist; sourcing quality is the reader's responsibility.