Tesamorelin (Egrifta®) is a stabilised synthetic analogue of GHRH(1-44) with a trans-3-hexenoic acid modification at the N-terminus that increases plasma stability and receptor affinity compared to native GHRH. It is the only GHRH analogue with full FDA approval — granted in 2010 for reduction of excess visceral abdominal fat in HIV-infected adults with antiretroviral therapy-associated lipodystrophy.
Unlike sermorelin (GHRH 1-29) or the modified CJC-1295 analogues, tesamorelin retains the full-length 44 amino acid sequence of GHRH. The trans-3-hexenoic acid modification at the N-terminal tyrosine residue provides resistance to DPP-IV cleavage — the primary plasma peptidase responsible for native GHRH degradation. This extends half-life to approximately 26-38 minutes versus 10-20 minutes for unmodified sermorelin, improving pharmacokinetics while maintaining physiological GH pulse characteristics.
Two pivotal Phase III randomised controlled trials formed the basis for FDA approval:
These trials established tesamorelin as the gold-standard reference for GH-axis-mediated visceral fat reduction in human research.
Visceral adipose tissue (VAT) is metabolically distinct from subcutaneous fat: it is more insulin-resistant, more pro-inflammatory (higher IL-6, TNF-α secretion), and more strongly associated with cardiovascular and metabolic disease risk. GH axis activity suppresses VAT accumulation through direct lipolytic effects (hormone-sensitive lipase activation) and anti-adipogenic effects on visceral preadipocytes. HIV-associated lipodystrophy features GH deficiency with elevated visceral fat — a model that clarified the GH/VAT relationship.
Tesamorelin reduces VAT by restoring GH pulse amplitude and IGF-1 to physiological levels, stimulating lipolysis in visceral adipocytes. Subcutaneous fat is largely spared because GH receptors in subcutaneous depots show different sensitivity profiles.
The VAT-reducing mechanism has driven interest in tesamorelin beyond HIV lipodystrophy. Research in general visceral obesity, metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD/NASH) has been published. Falutz et al. (2014) and subsequent investigators demonstrated benefits in liver fat reduction in HIV-associated metabolic dysfunction. Dhindsa et al. and others explored tesamorelin in age-related GH decline and central adiposity.
A Phase III trial in non-HIV adults with abdominal obesity is ongoing, examining tesamorelin as a metabolic intervention in the broader population — extending its research relevance beyond the original indication.
Emerging research has examined tesamorelin's effects on cognitive function in HIV-infected individuals and older adults. Improvements in verbal memory and executive function have been reported in small trials, potentially related to IGF-1's neuroprotective and synaptic plasticity-promoting effects in the hippocampus. This represents an active research frontier for GHRH analogues.
