Overview
In plain English
Tesamorelin is a stabilised analogue of growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. An N-terminal modification protects it from the enzyme that inactivates the native molecule within minutes.
It is studied in published research for GHRH receptor pharmacology and, in randomised controlled trials, for effects on visceral adipose tissue and hepatic fat measured by imaging — the most substantial trial literature of any GHRH analogue. Strictly for laboratory research use. Not for human or veterinary consumption.
- What it isA stabilised analogue of growth hormone-releasing hormone
- Mainly studied forGHRH receptor pharmacology, visceral adipose tissue and hepatic fat in imaging-based trials
- Supplied asLyophilised powder, 20mg vial, independently assayed
How it works
What it actually does
It acts on the pituitary GHRH receptor, prompting release of endogenous growth hormone — rather than supplying growth hormone directly.
That matters. Because the release remains the pituitary's own pulsatile system, the axis's natural feedback brakes stay in place instead of being overridden.
Growth hormone then raises lipolytic activity in adipose tissue. Visceral adipose tissue carries more growth hormone receptors than subcutaneous fat and is more lipolytically responsive, which is why the reported effects concentrate there.
The science in detail
Tesamorelin is a stabilised analogue of human growth hormone-releasing hormone. The native molecule, GHRH(1-44), is rapidly inactivated in circulation by dipeptidyl peptidase-4, which cleaves the N-terminal dipeptide and abolishes receptor activity. Tesamorelin carries a trans-3-hexenoyl group attached to the N-terminal tyrosine, which sterically obstructs that cleavage and materially extends the functional half-life while preserving affinity for the receptor.
The target is the GHRH receptor, a class B G-protein-coupled receptor expressed on pituitary somatotrophs. Agonism raises intracellular cAMP, activates protein kinase A, and increases both the synthesis and the pulsatile release of endogenous growth hormone. This is the mechanistically important distinction from exogenous recombinant growth hormone: tesamorelin amplifies the animal's own secretory pulses rather than imposing a continuous exogenous concentration, so the pituitary's negative feedback loops — somatostatin tone and IGF-1 feedback — remain intact and continue to constrain the response.
Downstream, elevated growth hormone acts on hepatic and peripheral GH receptors, raising IGF-1 and increasing hormone-sensitive lipase activity in adipose tissue. Visceral adipose tissue is comparatively rich in GH receptors and lipolytically responsive, which is the mechanistic basis for the tissue-selective findings reported in the clinical literature.
That literature is unusually solid for this compound class. Falutz et al. (New England Journal of Medicine, 2007) reported reductions in visceral adipose tissue in a randomised placebo-controlled trial, findings extended in a pooled analysis of two phase 3 trials. Stanley et al. (Lancet HIV, 2019) subsequently reported effects on hepatic fat fraction in a randomised, double-blind, multicentre trial.
Tesamorelin differs from growth hormone secretagogues such as ipamorelin, which act at the ghrelin receptor (GHS-R1a) rather than the GHRH receptor. The two pathways are distinct and, in research models, additive; CJC-1295 is the closer comparator, being a GHRH analogue of different design.
Evidence
What the research shows
Visceral adipose tissue is the reported target
Visceral fat is richer in growth hormone receptors and more lipolytically responsive, which is why trial findings concentrate there.
Acts through endogenous GH release
It amplifies the pituitary's natural pulses rather than replacing them with a flat exogenous concentration.
Randomised trial in NEJM
A reduction in visceral adipose tissue was reported in a New England Journal of Medicine randomised, placebo-controlled trial.
Hepatic fat also studied
A randomised trial published in Lancet HIV examined its effect on liver fat fraction.
Reconstitution & handling
Reconstitution and handling in the laboratory
These are general handling notes for the lyophilised peptide supplied by Purist Peptides. They describe the preparation of a stock solution for laboratory work. They are not a dosing protocol, and they describe no administration to a person or an animal.
A 3ml vial of bacteriostatic water is included free with every peptide vial you order, so the material can be reconstituted on arrival.
Tesamorelin 20mg — preparing a stock solution
Choice of diluent
Bacteriostatic water (water for injection with 0.9% benzyl alcohol) is the usual diluent where a stock will be drawn from repeatedly, because the preservative permits several septum entries across a working period. Sterile water for injection and sterile 0.9% sodium chloride are both used where a single-use preparation is wanted instead. The diluent volume sets the concentration of the stock, so record it.
Sterile technique
- Allow the sealed vial to reach room temperature before opening the carton — reconstituting a cold lyophilised cake slows dissolution
- Work in a clean area or a laminar flow cabinet, and wipe the rubber septum with 70% isopropyl alcohol, letting it dry fully
- Draw the chosen volume of diluent using a sterile single-use syringe and needle
- Angle the needle so the diluent runs down the inside wall of the vial — do not direct the stream onto the lyophilised cake
- Roll the vial gently between the palms until the cake has dissolved completely. Do not shake and do not vortex: peptides are surface-active, and agitation drives foaming and aggregation
- Let the vial stand for 5 to 10 minutes. A correctly reconstituted solution is clear and free of visible particles
Working out the concentration
Concentration follows from the mass in the vial and the volume of diluent added, nothing else. Adding 2ml of diluent to the 20mg vial gives a 10mg/ml stock; adding 4ml gives 5mg/ml. Label every reconstituted vial with its concentration and the date it was prepared.
Storage and stability
Before reconstitution
The lyophilised powder is the stable form. Sealed vials are best held at −20°C, protected from light and from moisture; the short periods at 2 to 6°C that occur in transit and on arrival are expected and are accounted for in the supply chain. Keep the vial in its carton — light and humid air are the two ordinary causes of loss on storage.
After reconstitution
Hold reconstituted solution at 2 to 6°C and protect it from light. Do not freeze a working stock: freeze-thaw cycling is the main avoidable cause of degradation and of visible precipitate. Where material must be held beyond a short working period, aliquot the stock into sterile low-binding tubes and freeze the aliquots once at −20°C or below, thawing each aliquot only once.
Checks before use
Inspect every vial against a light source. Discard any solution that is hazy, discoloured or contains particles, and any vial whose septum integrity is in doubt. The independent HPLC assay report for the batch supplied is available on request.
Strictly for laboratory research use. Not for human or veterinary consumption.
Questions
Frequently asked questions
How does tesamorelin differ from exogenous growth hormone?
Recombinant growth hormone supplies the hormone directly, overriding pituitary regulation. Tesamorelin acts one step upstream at the GHRH receptor, amplifying the pituitary's own pulsatile secretion. Somatostatin tone and IGF-1 negative feedback remain intact, so the physiological pattern of release is preserved in research models.
How does it differ from ipamorelin or CJC-1295?
Ipamorelin is a ghrelin receptor (GHS-R1a) agonist — a different receptor and a different pathway. CJC-1295 is the closer comparator, being a GHRH analogue, though of different structural design. Tesamorelin is the GHRH analogue with the most substantial randomised controlled trial literature behind it.
What has tesamorelin been studied for?
Its principal published trials examined visceral adipose tissue measured by CT (Falutz et al., NEJM, 2007, and a pooled phase 3 analysis) and hepatic fat fraction (Stanley et al., Lancet HIV, 2019). Purist supplies the compound for laboratory research only.
Why is visceral fat a distinct research target?
Visceral adipose tissue differs from subcutaneous fat in receptor density, lipolytic responsiveness and metabolic activity. It is comparatively rich in growth hormone receptors, which is the mechanistic basis for the tissue-selective effects reported in the tesamorelin trials.
How is purity verified?
Every batch is assayed by independent HPLC at Bioindustrial Services in Boksburg. We do not rely on the manufacturer's own certificate alone. The assay report for the batch you receive is available on request, and our full testing protocol is set out at Quality Standards.
How long does delivery take?
Orders are dispatched from South Africa, with timelines varying by region and courier. Current dispatch and transit windows are set out at Delivery Process.
Can I return an order?
Because these are laboratory compounds, returns are not accepted once an order has shipped. If your parcel arrives damaged, contact us within 48 hours with photographs of the packaging and product and we will arrange a replacement. The full terms are set out in our Refund Policy.
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