Tesamorelin: the GHRH analogue that actually got a licence

Tesamorelin is a growth-hormone-releasing hormone. Native GHRH is a 44-residue peptide the hypothalamus drips onto the pituitary, and the pituitary answers with a pulse of growth hormone. DPP-IV, a boring protease in the blood, cuts native GHRH within a few minutes, which is why the natural signal is a spike and a silence. Tesamorelin is that same 44-residue chain with a trans-3-hexenoyl group hung on the first tyrosine. The tag makes the protease's job harder. The pulse lasts longer than a native drip and nothing like the multi-day smear you get when a maleimide glues a shorter GHRH analogue to albumin. That glue is CJC-1295 with DAC. Tesamorelin is the other idea: keep the pulse, just stop the enzyme eating it before the somatotroph has heard it.

In short. Tesamorelin is the body's own growth-hormone signal, slightly armoured so an enzyme doesn't destroy it in minutes. It still pulses. It does not sit on you for days.

The receptor is the GHRH receptor, a class-B G protein-coupled receptor on the somatotroph. It works through Gs and cyclic AMP, which is a different lock from the ghrelin receptor that ipamorelin uses. Same cell, two doors, and Bowers showed years ago that opening both at once releases more growth hormone than either door alone. Tesamorelin only has a key to the GHRH door. It does not bind the androgen receptor, it does not aromatise, and it is not a steroid, whatever a forum category has done with the word peptide. Growth hormone then reaches the liver, JAK2 and STAT5 write IGF-1, and IGF-1 is the number a blood test actually moves over weeks. A single growth-hormone spike is a few minutes. The IGF-1 is the integral.

In short. It presses the GHRH receptor, not the ghrelin receptor and not the androgen receptor. Growth hormone is the immediate reply. IGF-1 from the liver is what you measure later.

The licence is narrow and the trial is not a gym study. Falutz and colleagues, New England Journal of Medicine, 2007: people with HIV-associated lipodystrophy, excess visceral fat, a daily subcutaneous injection, six months. Visceral fat fell by about fifteen percent against a placebo group that did not shrink. Subcutaneous fat barely moved. That split is the interesting part. Visceral adipose tissue is the depot wrapped around the organs, the one that tracks insulin resistance and liver fat. Tesamorelin reduced that depot while IGF-1 rose. Triglycerides tended to improve. Fasting glucose and insulin did not get a free pass, and in some people glucose tolerance nudged the wrong way, because growth hormone is a hormone that raises blood sugar even while it is burning fat. The FDA approval, under the name Egrifta, is for that HIV indication. It is not a general fat-loss licence, and it is not a hypertrophy licence. The trial tells you the receptor works in humans and that the fat it moves is the visceral kind.

In short. In a proper trial, in people with HIV and a lot of organ fat, daily tesamorelin shrank that fat by about fifteen percent in six months. It also raised IGF-1, and it can nudge blood sugar the wrong way.

A later extension asked what happens when you stop. The visceral fat came back. That is the most useful sentence in the follow-up. The drug was holding a distribution, not rewriting the adipocyte into a new kind of cell. Take the GHRH signal away and the depot refills, because the rest of the life — energy, insulin, the virus, the other drugs — was still there. People read a fifteen percent number and file tesamorelin under permanent recomposition. The stop data says the number was an occupancy of a receptor. The catalogue on this site does not stock tesamorelin. The GHRH analogue it does stock is modified GRF(1–29) without DAC, which is the same receptor and a shorter chain, built to be gone in tens of minutes on purpose.

In short. Stop the drug and the organ fat tends to return. It was holding a signal, not curing the depot. This site stocks the short GHRH analogue, CJC without DAC, not tesamorelin.

Four names get mashed into one syringe in people's heads. Tesamorelin is a 44-residue GHRH with a fatty tag, licensed, pulsatile, GHRH receptor only. CJC-1295 without DAC is modified GRF(1–29), also a GHRH-receptor agonist, also short, the one on this shelf. CJC-1295 with DAC adds a drug-affinity complex that binds albumin and stretches the half-life into days, which flattens the pulse into something closer to a continuous drip. The pituitary prefers pulses. A continuous growth-hormone signal is how you walk toward the pattern of acromegaly, high IGF-1 with no night and no trough. Ipamorelin is not in this family at all. It is five residues aimed at the ghrelin receptor, GHS-R1a, and it amplifies the pulse only if the GHRH side is also speaking. Somatropin is the 191-residue hormone itself. No pituitary required. That is a different risk, a different glucose bill, and a different conversation from a releasing hormone.

In short. Tesamorelin and CJC without DAC both pulse the GHRH receptor. CJC with DAC smears that pulse over days. Ipamorelin is the other receptor. Somatropin skips the pituitary and is the hormone.

The bill, when this axis is pushed, is not a mystery. IGF-1 goes up. Water follows growth hormone, at the kidney and in the tissues, so a scale can move before a tape measure of muscle does. Fasting glucose can rise. A person with diabetes was never the trial population you want to improvise on. Active cancer is the other place a rising IGF-1 signal is the wrong experiment, which is why the licensed label says so. None of that makes the molecule a steroid, and none of it makes a short GHRH analogue a substitute for food and a barbell. The fibre still needs tension and amino acids. Growth hormone mostly frees fatty acids and asks the liver for IGF-1. Myosin is a slower, pickier customer.

In short. Expect higher IGF-1, some water, and a possible rise in fasting glucose. It is not a steroid, and it does not lay down myosin by itself.