Tesamorelin common uses, half-life, side effects and more

Tesamorelin is a synthetic copy of the hormone the brain uses to tell the pituitary to release growth hormone, with a chemical cap that stops it being broken down. It has been an approved prescription drug in the United States since 2010. It is not on the market in Europe or Canada. The approval covers one narrow use. That use is reducing excess belly fat in adults with HIV who have lipodystrophy. It is the only approved drug of its kind still sold. Almost everyone taking it outside that indication is doing so off label for body composition. It is also sold through unregulated research-chemical channels.

• Reducing excess belly fat in HIV lipodystrophy (the approved use)
• Body composition and visceral fat in people without HIV
• Raising growth hormone without injecting growth hormone itself
• Liver fat in fatty liver disease
• Stacking with a ghrelin receptor agonist

Once daily

The approved dose is 1.28 mg under the skin once a day for Egrifta WR. The older product it is replacing is Egrifta SV and its dose is 1.4 mg. Both sit below the 2 mg used in the trials. The newer formulation delivers more drug per milligram. Community practice has not caught up and almost everyone still injects 2 mg. That is 43 to 56 percent above either label. Reported community amounts run from 250 mcg to 2.5 mg. The two are not interchangeable and the label states that directly.

• Mix Egrifta WR once and use it for seven daily injections while Egrifta SV is mixed fresh every day
• Inject into the abdomen at least two inches from the navel and rotate sites

The half-life is 8 to 11 minutes depending on the formulation. Both figures come from single doses under the skin in healthy volunteers. A longer figure of 26 to 38 minutes circulates widely and traces to an unpublished company document rather than to any label. Less than 4 percent of a skin injection reaches the blood. The short half-life does not conflict with once-daily dosing. The growth hormone and IGF-1 it triggers outlast the peptide by hours.

Egrifta SV must be injected immediately after mixing and the rest thrown away. Egrifta WR is mixed once and kept at room temperature for seven days. Its label says specifically not to refrigerate or freeze it after mixing.

• Injection site reactions in 17 percent against 6 percent on placebo
• Joint pain in 13 percent against 11 percent on placebo
• Muscle aches and swelling in the hands and feet, each about three times the placebo rate
• Pins and needles or numbness in about one person in twenty
• Antibodies to the peptide in half of patients without affecting how well it worked

Tesamorelin is the full 44 amino acid growth hormone releasing hormone with a fatty acid chain added to one end. That chain blocks the enzyme that would otherwise clip the natural hormone apart within minutes. It activates the same pituitary receptor with similar strength. The pituitary then releases your own growth hormone. That raises IGF-1 from the liver. Growth hormone release stays pulsatile and the pulses get bigger rather than more frequent. Only the fat deep in the abdomen responds. Fat under the skin did not change in the approval trials or in the trial in people without HIV. The effect does not outlast the treatment and visceral fat returns within weeks of stopping.

Two randomized trials of 816 people supported the US approval and both hit their target. Visceral fat fell 15.2 percent in one against a 5.0 percent gain on placebo. It fell 10.9 percent in the other against 0.6 percent. About a third of treated patients did not respond and that group gained visceral fat rather than merely failing to lose it. The European Medicines Agency reviewed the same evidence and reached the opposite conclusion. It judged the benefit did not outweigh the risk, called the visceral fat measure clinically unvalidated, and flagged the IGF-1 rise as a major concern. The company withdrew the application rather than take a formal refusal. Everyone in those trials had HIV. Four later trials have studied people without HIV and not one of them measured muscle, strength, or performance.

• It raises the odds of crossing into diabetes more than threefold and 5 percent of treated patients did so within six months against 1 percent on placebo
• Nobody has ever tested it for muscle, strength, or performance in healthy adults
• It is banned in sport at all times and the World Anti-Doping Agency names it directly
• Active cancer rules it out and no lifetime cancer study has ever been run in animals
• Avoid it in pregnancy since it caused fluid on the brain in rat offspring at about twice the human exposure
• Egrifta SV and Egrifta WR are not interchangeable and each carries its own dose and mixing instructions