Mechanism of action
Tesamorelin is an agonist at the growth hormone-releasing hormone receptor (GHRH-R) on somatotroph cells of the anterior pituitary. Receptor binding activates Gs-protein-coupled signaling (cAMP/PKA) and stimulates the synthesis and pulsatile release of endogenous growth hormone (GH), which in turn drives hepatic IGF-1 production. Because the axis remains under negative feedback by somatostatin and IGF-1, the physiological secretion pattern is largely preserved, a distinction from administration of exogenous GH. Structurally, tesamorelin corresponds to human GHRH(1-44) carrying a trans-3-hexenoyl group at the N-terminus; this modification increases resistance to degradation by dipeptidyl peptidase-4 (DPP-4). The plasma half-life nonetheless remains short and is reported in the literature at roughly 30 minutes (literature estimate). Downstream effects on lipolysis and visceral adipose tissue have been examined in clinical trials.
State of evidence
Tesamorelin is one of the few peptides in this class with regulatory approval: in 2010 the US FDA approved it under the brand name Egrifta for the reduction of excess visceral abdominal fat in adults with HIV-associated lipodystrophy. The approval rests on randomized, placebo-controlled multicenter trials (Falutz et al., NEJM 2007; Falutz et al., JAIDS 2010), in which tesamorelin reduced visceral adipose tissue compared with placebo; the effect regressed after discontinuation in the extension phases. Further clinical work has examined, among other endpoints, muscle fat content and muscle area in adults with HIV (Adrian et al., 2019). Important context: the approval covers only this narrowly defined indication. For other fields of application, such as metabolic or body-composition questions outside the HIV population, no approval exists and the data remain limited. Long-term data on hard clinical endpoints are lacking, and effects on the IGF-1 axis are discussed in the literature as requiring monitoring. No conclusions about efficacy or safety outside controlled studies can be drawn from this evidence.
Storage and handling
Lyophilized peptides are generally stored cool, dry, and protected from light in a sealed container. After reconstitution with a suitable solvent, the solution is typically kept refrigerated (2 to 8 °C) and used within a few days. These are generic handling notes for lyophilized peptides, not product-specific stability data.
Questions about the research
- What is tesamorelin studied for in research?
- The focus is the growth hormone axis: as a GHRH analog, tesamorelin stimulates the pulsatile release of endogenous growth hormone. The best-studied clinical context is the reduction of visceral adipose tissue in HIV-associated lipodystrophy, the indication for which the FDA approved the substance as Egrifta. Studies have additionally examined body-composition endpoints such as muscle fat content in adults with HIV.
- What is the state of the evidence on tesamorelin?
- Randomized, placebo-controlled multicenter trials exist for the approved indication, on the basis of which the FDA granted approval in 2010. Outside this narrowly defined indication the data remain limited, and no approval exists for other fields of application. Long-term data on hard clinical endpoints are lacking, so no conclusions about efficacy or safety outside controlled studies can be drawn.
Sources
- Falutz et al., NEJM 2007DOI: 10.1056/NEJMoa072375PMID: 18057338
- Falutz et al., JAIDS 2010DOI: 10.1097/QAI.0b013e3181cbdaffPMID: 20101189
- Adrian et al., J Frailty Aging 2019DOI: 10.14283/jfa.2018.45PMID: 31237318
- Drugs@FDA: Egrifta (Tesamorelin), BLA 022505