Tesamorelin: Reference Overview and Reconstitution Notes

Tesamorelin is a man-made copy of a natural signaling molecule that tells the body to release growth hormone. It belongs to a group called growth-hormone secretagogues (compounds that prompt the body to produce more of its own growth hormone). It has been studied for its effects on body fat and metabolism, and it has one FDA-approved use.

What it is

Tesamorelin is a synthetic (man-made) version of a natural human protein called growth-hormone-releasing factor (GRF, also called growth-hormone-releasing hormone or GHRH). Think of GHRH as a chemical messenger that signals a small gland at the base of the brain, called the pituitary gland, to release growth hormone.

Tesamorelin is built from the same 44 amino acids (the building blocks of all proteins) as that natural messenger. A small chemical group called a hexenoyl group is attached to one end of the chain. This addition helps protect the molecule from enzymes (proteins that break other molecules apart). That protection makes Tesamorelin more resistant to breakdown than the natural version, placing it in the growth-hormone secretagogue family of peptides (short protein chains).

Key point: Tesamorelin works like the body's own signaling molecule. It prompts the pituitary gland to release growth hormone in natural bursts, which then acts to reduce deep belly fat.

Research context and categorization

Researchers group Tesamorelin with growth-hormone secretagogues. These are compounds that encourage the body to make its own growth hormone, rather than adding growth hormone from an outside source. It is also studied in the area of metabolic and visceral-fat (deep belly fat) research.

It is described as acting on special cells in the pituitary gland called somatotrope cells. Those cells respond by releasing growth hormone in natural pulses, short bursts much like a sprinkler that turns on and off in cycles. That released growth hormone then works through a chain of signals that also involves a molecule called IGF-1 (insulin-like growth factor 1, a protein that carries growth hormone's messages to tissues).

In its one FDA-cleared use, Tesamorelin is applied to reduce extra visceral (deep abdominal) fat, the fat that sits around internal organs deep in the belly, in people with HIV-associated lipodystrophy (an abnormal change in body fat caused by HIV or its treatments).

Beyond that approved use, researchers have looked at Tesamorelin in connection with liver fat and a liver condition called non-alcoholic fatty liver disease (NAFLD/MASLD). Some studies have also explored possible effects on memory and thinking in older adults. These are investigational (still being studied) areas. The effects in these areas have not been confirmed or approved.

Status

• Regulatory status: FDA-approved for one specific use: reducing excess belly fat in people with HIV-associated lipodystrophy (sold under the Egrifta family of brand names). Any use outside that specific purpose is considered investigational.
• Sport status: Prohibited under the WADA Prohibited List (the global anti-doping rules for sport). It falls under the S2 category (Peptide Hormones, Growth Factors, Related Substances and Mimetics), in the growth-hormone-releasing factors subclass. It is banned at all times, both during and outside of competition.

Reconstitution notes (general)

Tesamorelin ships as a lyophilized (freeze-dried) powder. Freeze-drying removes water from the compound to make it more stable during storage. Before lab use, it is mixed with bacteriostatic water (sterile water with a small preservative added to slow bacterial growth).

The working concentration is simple to figure out. Divide the milligrams in the vial by the milliliters of bacteriostatic water added. For example, 5 mg mixed with 2.5 mL gives 2 mg/mL. To check your own numbers, see the calculator at peptide calculator.

Dilution and handling notes (compound-specific)

Common Dilution Ratios

Most reported preparations land around 2 mg/mL. Common vial sizes in reference material are 2 mg, 5 mg, and 10 mg. The amount of water used is mainly a choice about what concentration the researcher wants to work with, not a hard limit based on how much will dissolve. Mixing on the more dilute side (adding more water) is often preferred because the compound dissolves cleanly and draws into a syringe accurately.

Some example numbers from that reference range:

• A 2 mg vial with 1 mL gives about 2 mg/mL.
• A 5 mg vial with roughly 2.5 mL gives about 2 mg/mL.
• A 10 mg vial with 3 mL gives about 3.33 mg/mL.

Reconstitution Technique

Tesamorelin generally dissolves easily. Once fully mixed, it should look like a clear, colorless liquid with no visible particles or cloudiness. This usually takes a couple of minutes.

Tesamorelin is described as a fragile peptide, a delicate protein chain that can be damaged by rough handling. The key is to be gentle:

• Add the bacteriostatic water slowly by running it down the inside wall of the vial. Do not aim the stream directly at the powder.
• Swirl gently and let the powder dissolve on its own.
• Do not shake the vial hard. Vigorous shaking can cause foaming and is thought to put stress on the peptide chain.

If the solution stays cloudy, shows particles, or does not clear up, treat it as unusable. This is a reconstituted freeze-dried powder, not an oral tablet, a small-molecule liquid, or a pre-mixed solution.

Handling and storage

To keep the compound stable, follow these handling and storage steps:

• Keep the reconstituted solution refrigerated at 2 to 8 C and out of direct light.
• Wipe the vial stopper with an alcohol swab before drawing from the vial.
• Write the mix date on the vial label so you can track how long it has been open.
• When mixed with bacteriostatic water and kept refrigerated, a common working window is about four weeks. Some references suggest shorter use windows, or freezing small portions (called aliquots) for longer storage.
• Throw away any vial that turns cloudy or discolored, or that shows floating particles.

Related reading

• Tirzepatide
• EPO
• Gonadorelin
• How Reconstitution Works
• How Long Does a Reconstituted Vial Last?

Tools and supplies

• peptide calculator
• Bacteriostatic Water 30 ml
• Gansulin Metal Reusable Pen
• 3 ml Glass Cartridges (10-pack)
• Complete Starter Kit

Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.

Frequently asked questions

What makes Tesamorelin different from natural GHRH?

Tesamorelin shares GHRH's 44-amino-acid sequence but adds a hexenoyl group at one terminus, increasing resistance to enzymatic degradation and improving stability compared with the unmodified natural peptide.

What is Tesamorelin's FDA approval and WADA classification?

It has one FDA approval: reducing excess visceral fat in HIV-associated lipodystrophy (brand: Egrifta). WADA lists it as prohibited at all times under S2, growth-hormone-releasing factors subclass.

Why is Tesamorelin shipped as lyophilized powder?

Freeze-drying removes water to maximize shelf stability and minimize degradation during storage and transit. The powder is reconstituted with bacteriostatic water immediately before laboratory use.

What the research community gets wrong about Tesamorelin

• It is not growth hormone in a vial. Tesamorelin is a growth-hormone-releasing factor analog. In a study system it acts as a signaling molecule, not as a stock of growth hormone itself. A vial labeled Tesamorelin and a vial of recombinant growth hormone are two different reference materials and should not be logged or handled as if they were the same thing.
• It is not the same molecule as plain GHRH (1-44). Tesamorelin carries an added trans-3-hexenoyl group at one end of the chain. That change makes it more resistant to enzyme breakdown, so reference data for native GHRH does not automatically transfer to it. Treat them as separate entries in your notes.
• The FDA product handling is not the same as general reference-range handling. The approved Egrifta label reconstitutes with sterile water for injection, rolls the vial gently for about 30 seconds, and uses the solution right away rather than storing it. Many reference ratios written for the research setting assume bacteriostatic water and a multi-week refrigerated window. These are different procedures, so do not cite one as proof of the other.
• Cloudiness after mixing is not always leftover powder. This is described as a fragile peptide. Hard shaking and foaming create an air and liquid interface that can stress the chain and cause haze even after the solid has gone into solution. If a gently swirled vial clears and a shaken one does not, the handling, not the amount of water, is the likely difference.
• More water does not mean a weaker or lower-quality prep. The milligrams per milliliter is a concentration choice, not a limit on how much will dissolve. Adding more bacteriostatic water simply gives a more dilute solution that can be easier to draw accurately. It does not change the total amount of compound in the vial.

From our bench: If you reconstitute a Tesamorelin vial, tell us what you actually saw. How long did the powder take to go fully clear after you added bacteriostatic water and swirled gently, and did a slower stream down the vial wall cut down on foaming compared with a faster add? Note the vial size and the volume of water you used so the observation is repeatable, and please share only what you measured, with no numbers filled in for you.

Sources

1. Bacteriostatic Water for Injection, USP , FDA/DailyMed label (0.9% benzyl alcohol)
2. Duerkop et al., Biotechnol J 2018 , Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation
3. Sigma-Aldrich (Merck) , Handling and Storage Guidelines for Peptides and Proteins
4. PubChem: Tesamorelin (CID 16137828), compound record and molecular formula
5. Falutz J, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med, 2007 (PMID 18057338)
6. FDA/DailyMed: EGRIFTA SV (tesamorelin) label, indication and reconstitution