October 10, 2026 · 2 min read

Tesamorelin: a growth hormone-releasing factor analogue and visceral fat research

What tesamorelin is, how it acts on the growth hormone axis, and what the published HIV lipodystrophy trials report about visceral adipose tissue.

Tesamorelin is a synthetic analogue of growth hormone-releasing hormone (GHRH), also called growth hormone-releasing factor. Some countries have approved it for one specific condition, excess abdominal fat in HIV patients with lipodystrophy, and researchers have looked at it in other settings too. Here is what the published literature says.

The tesamorelin sequence

Polar
Hydrophobic
Negatively charged
Positively charged
Glycine or proline

Length: 44 amino acids
Average mass: 5,136 Da
Formula: C221H366N72O67S

Human GHRH residues 1 to 44 (UniProt P01286, positions 31 to 74), with a trans-3-hexenoyl group on the N-terminal tyrosine and a C-terminal amide. The mass calculated for the modified chain matches PubChem (CID 16137828).

Mechanism

The hypothalamus makes GHRH, which tells the pituitary to release growth hormone (GH) in pulses. Natural GHRH is broken down within minutes. Tesamorelin binds the same receptor but is modified to resist that breakdown. Because it works upstream of the pituitary, the GH that gets released is still subject to the body's own feedback controls. That is the main difference from giving GH directly.

The growth hormone axis

1
Hypothalamus
Makes GHRH, which is cleared within minutes.
2
Pituitary
Releases growth hormone in pulses when GHRH binds.
3
Tesamorelin
A GHRH analogue modified to resist breakdown, acting at the same receptor.
4
Feedback
Because it acts upstream, GH release still follows the body's own controls.

Simplified from the descriptions in the cited papers. Illustrative only.

The HIV lipodystrophy trials

Antiretroviral therapy for HIV can come with a buildup of visceral adipose tissue (VAT), the fat around the internal organs. In the 26-week phase 3 trials, daily subcutaneous tesamorelin reduced VAT and improved lipids. A 26-week extension then followed 410 patients who had been randomized to 2 mg of tesamorelin or placebo.

In the extension, the VAT reduction held at -18% over 52 weeks and triglycerides stayed down by 51 mg/dl. The authors report that treatment was generally well tolerated and glucose parameters changed in ways that were not clinically significant. VAT came back after tesamorelin was stopped, so the benefit lasted only as long as treatment did.

How the trial and extension ran

1
Weeks 0 to 26
273 patients on tesamorelin, 137 on placebo.
2
Week 26
Re-randomized: 154 stayed on tesamorelin, 50 switched to placebo, 111 placebo patients switched to tesamorelin.
3
Week 52
Visceral fat down 18% and triglycerides down 51 mg/dl versus baseline.
4
After stopping
Visceral fat reaccumulated.

From Falutz et al., AIDS 2008: 2 mg tesamorelin daily versus placebo, with a 26-week extension. T-T, T-P and P-T are the extension groups.

Reviews

Two 2011 drug reviews, in Drugs and BioDrugs, cover the whole clinical program: VAT results, lipid effects and adverse events. They are the quickest way to get the regulatory-style overview.

Reading these results

The findings apply to people with HIV and excess abdominal fat on antiretroviral therapy. They don't show the same effect in other groups. They also illustrate something common in endocrine research: a reduction measured on treatment is not a lasting change.

Check the primary outcome. Visceral fat on a CT scan is not the same as body weight.
Look at the control arm and at what happened after treatment ended.
Long-term safety data are thinner than for older drugs.

Tesamorelin is 44 amino acids long, which makes batch-level identity and purity testing especially worth checking on a certificate of analysis.