Tesamorelin, marketed as EGRIFTA, is a synthetic analog of the native 1-44 amino acid GHRH sequence. The hypothalamic peptide it mimics is normally cleared within about five minutes by dipeptidyl peptidase-4 in circulation. A trans-3-hexenoic acid modification stabilizes the molecule, extending its half-life to roughly half an hour and making subcutaneous dosing practical. This lesson covers its FDA approval, mechanism, and clinical evidence.

The mechanism begins at the growth hormone releasing hormone receptor, a G-protein coupled receptor on the anterior pituitary. High-affinity binding activates adenylyl cyclase, raises cyclic AMP, and drives PKA signaling toward gene transcription and protein synthesis. Because tesamorelin works upstream, it stimulates pulsatile endogenous growth hormone release and preserves somatostatin negative feedback, keeping IGF-1 within age-adjusted ranges. Exogenous growth hormone, by contrast, produces continuous super-physiologic signaling and loses that feedback.

On safety, the lesson notes no significant A1C worsening, with IGF-1 staying within normal range. Tesamorelin is contraindicated in pregnancy, active malignancy, and a disrupted HPA axis. Common adverse effects include injection-site reactions, arthralgias, myalgias, peripheral edema, paresthesias, and headaches, many of them dose-related or transient.

Practical administration: reconstitute with bacteriostatic water, inject subcutaneously into the abdomen or hip area, and rotate sites to avoid scar tissue and bruising. Monitoring may include IGF-1, fasting glucose, hemoglobin A1C, lipid panels, and liver enzymes, with visceral fat tracked by CT imaging, waist circumference, or in-body testing.

Key clinical points

• Visceral-selective fat reduction: Phase three data showed roughly 17.5% reduction in visceral adipose tissue at 26 weeks, with subcutaneous fat largely preserved. Responder rates ran about 69% at 26 weeks and 72% at 52 weeks.
• FDA status: Approved in 2010 for reduction of excess abdominal fat in HIV-infected patients with lipodystrophy. The product originates from a Montreal company.
• Hepatic effects: An NIH-funded study in HIV-associated fatty liver disease reported up to a 37% reduction in hepatic fat fraction and reduced fibrosis progression, linking visceral fat reduction to improved hepatic steatosis.
• Downstream pathways: Increased lipolysis via hormone-sensitive lipase, improved beta oxidation through AMPK and mitochondrial biogenesis, higher adiponectin, and inhibition of 11-beta hydroxysteroid dehydrogenase type 1, which can reduce intracellular cortisol activation.
• Emerging signals: Increased GABA across three brain regions, reduced myo-inositol as a cognitive biomarker, and improved muscle density in trunk muscle groups.