Supplying growth hormone versus prompting the pituitary to release its own. That difference is the entire argument: tesamorelin preserves pulsatile secretion and the feedback loop that exogenous hGH bypasses.
Side by side
| HGH (Somatropin) | Tesamorelin | |
|---|---|---|
| Class | Recombinant human growth hormone | GHRH analog |
| Status | FDA approved (somatropin brands); gray-market generics unapproved | FDA approved |
| Route | Subcutaneous injection | Subcutaneous injection |
| Typical vials | 10 IU, 12 IU, 24 IU, 36 IU | 5 mg, 10 mg |
| Dose range | 1 IU to 4 IU | 1 mg to 2 mg |
| Frequency | Once daily, often 5 to 7 days per week | Once daily |
| Half-life | ~3 hours | ~38 minutes |
| Dosing unit | IU | milligrams |
Pharmacokinetics
What the evidence supports
These grade how well each outcome has been studied in humans, never how well either compound works. A strong grade can sit on a negative result.
Both top out at the same tier of evidence: Human RCT. Where they differ is in which outcomes have been asked about, not in how well either has been studied overall.
HGH (Somatropin)
| Outcome | Evidence |
|---|---|
| Body composition in diagnosed GH deficiency | Human RCT |
| Growth in GH-deficient children | Human RCT |
| Body composition in healthy adults | Human, observational |
| Anti-aging outcomes in healthy adults | No data |
Tesamorelin
| Outcome | Evidence |
|---|---|
| Visceral fat reduction in HIV lipodystrophy | Human RCT |
| Cognitive function | Human, observational |
| Visceral fat reduction in other populations | Human, observational |
How to choose
hGH is replacement therapy and is dosed as such
Nearly all of its trial evidence comes from people with a measured deficiency, which is not the population usually interested in it.
Tesamorelin's evidence is specific and narrow
It is approved for HIV-associated lipodystrophy, and that is the population its visceral-fat data comes from.
Feedback intact is a mechanistic argument, not an outcome
Preserving pulsatility is biologically reasonable. No trial has shown it produces better outcomes than hGH in a shared indication.
Both are dosed in units that trip people up
hGH is dosed in IU at roughly 3 IU per mg. Tesamorelin is dosed in mg. The unit converter handles the conversion, and the IU factor does not transfer between compounds.
At the syringe
At the default setup on each compound's own page, a 10 IU vial in 2 mL puts 0.05 IU on every insulin unit, while a 5 mg vial in 2 mL puts 25 mcg on every unit. That is the number that decides whether a dose lands on a readable mark, and it is set by how much water goes in, not by the compound.