How Tesamorelin Works: Mechanism and Pharmacology
How Tesamorelin works: its target and mechanism as the sources state them, how long it acts, and what is still unknown.
- Class
- GHRH analog
- FDA status
- Approved (Egrifta)
- Routes studied
- subcutaneous; subcutaneous (once daily, per abstract); subcutaneous (per trials)
- Half-life
- 11 minutes
- subcutaneous (EGRIFTA WR 1.28 mg), in people · FDA label (Egrifta WR)
How long it acts
Half-life values from FDA labels and published studies, by route. Animal values are labelled and do not describe people.
| Route | Half-life | Measured in | Source |
|---|---|---|---|
| subcutaneous (EGRIFTA WR 1.28 mg) | 11 minutes | People | FDA label (Egrifta WR) |
| subcutaneous (EGRIFTA SV 1.4 mg) | 8 minutes | People | FDA label (Egrifta SV) |
| As labelled | 11 minutes (single 1.28 mg subcutaneous dose, healthy subjects) | People | FDA label (Egrifta WR) |
| As labelled | 8 minutes (single 1.4 mg subcutaneous dose, healthy subjects) | People | FDA label (Egrifta SV) |
Full detail, including drug-testing windows, is on the Tesamorelin half-life page.
Target and mechanism, from the label
In vitro, tesamorelin binds and stimulates human growth hormone-releasing factor receptors with similar potency to the natural hormone.[2]
The label explains that GHRH acts on pituitary somatotroph cells to stimulate the synthesis and pulsatile release of growth hormone, which is anabolic and lipolytic.[2]
Pharmacodynamics: tesamorelin stimulates GH secretion and then raises IGF-1 and IGFBP-3, without clinically significant changes in other pituitary hormones such as TSH, LH, ACTH and prolactin.[1]
Why it is given daily: half-life and design
The Egrifta SV label gives a mean elimination half-life of 8 minutes after a single subcutaneous 1.4 mg dose in healthy subjects.[2]
The Egrifta WR label gives a mean elimination half-life of 11 minutes after a single 1.28 mg dose in healthy subjects.[1]
Tesamorelin is a modified GRF peptide in which a trans-3-hexenoyl group on Tyr1 makes it resistant to dipeptidyl aminopeptidase-IV breakdown.[3]
The label states the absolute bioavailability of a 2 mg subcutaneous dose was less than 4% in healthy adults.[2]
A population pharmacokinetic model estimated clearance at 1,060 L/h and volume of distribution at 200 L.[4]
What it did in people
Daily 1 or 2 mg raised IGF-I in a dose-related way, by 48% and 65% versus placebo.[5]
In the pivotal trial, IGF-I rose 81.0% on tesamorelin and fell 5.0% on placebo, alongside the visceral fat reduction.[6]
In a controlled trial in older adults, tesamorelin raised IGF-1 by 117%, which remained within the physiological range.[7]
The same trial reported a favourable effect on cognition in both adults with mild cognitive impairment and healthy older adults.[7]
Related peptides
Common questions
How long does Tesamorelin act in the body?
The half-life values we found are 11 minutes (subcutaneous (EGRIFTA WR 1.28 mg)); 8 minutes (subcutaneous (EGRIFTA SV 1.4 mg)). A half-life is how long the amount in the body takes to fall by half; it is not the same as how long an effect lasts.
How does tesamorelin work?
It stimulates GRF receptors on the pituitary so the body releases more of its own growth hormone.[2]
How long for tesamorelin to work?
In the pivotal trial the visceral-fat change was measured as the percent change from baseline on CT scans.[6]
More on Tesamorelin
Sources
- 1EGRIFTA WR (TESAMORELIN) KIT [THERATECHNOLOGIES INC.]FDA label (Egrifta WR), DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
- 2EGRIFTA SV (TESAMORELIN) KIT [THERATECHNOLOGIES INC.]FDA label (Egrifta SV), DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
- 3Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue.Basic & clinical pharmacology & toxicology · 2007PMID 17214611Accessed 11 Oct 2026
- 4Population pharmacokinetic analysis of tesamorelin in HIV-infected patients and healthy subjects.Clinical pharmacokinetics · 2015PMID 25358450Accessed 2 Oct 2026
- 5A placebo-controlled, dose-ranging study of a growth hormone releasing factor in HIV-infected patients with abdominal fat accumulation.AIDS (London, England) · 2005PMID 16052083Accessed 2 Oct 2026
- 6Metabolic effects of a growth hormone-releasing factor in patients with HIV.The New England journal of medicine · 2007PMID 18057338Accessed 2 Oct 2026
- 7Effects of growth hormone–releasing hormone on cognitive function in adults with mild cognitive impairment and healthy older adults: results of a controlled trial.Archives of neurology · 2012PMID 22869065Accessed 2 Oct 2026
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