Tesamorelin & Ipamorelin

The tesamorelin ipamorelin blend, often shortened to Tesa/Ipa, is a two-component research material supplied in a single lyophilized vial: 8MG tesamorelin and 2MG ipamorelin. The components act on growth hormone release through different receptors. Tesamorelin is a stabilized analog of growth hormone-releasing hormone (GHRH); ipamorelin is a synthetic pentapeptide secretagogue acting at the receptor whose natural ligand is ghrelin.

Each has its own literature, from cell culture to clinical trials, but no published study has tested the two together. This guide summarizes each component with its study model and sets out what is and is not known about the pairing.

By mass the vial is 80% tesamorelin, but at those molecular weights 8MG of tesamorelin is about 1.6 micromoles and 2MG of ipamorelin about 2.8 micromoles, so ipamorelin is the larger component by moles. Salt form and measured content shift these figures.

Tesamorelin

Tesamorelin keeps the full human GHRH(1-44) amide sequence and adds a trans-3-hexenoyl group to the N-terminal tyrosine. In non-clinical studies that change made it resistant to dipeptidyl aminopeptidase-IV and slowed its breakdown in rat, dog and human plasma, and repeated daily administration raised growth hormone and IGF-1 in pigs, rats and dogs (Ferdinandi et al., 2007). In 13 healthy men studied over two weeks it increased mean overnight growth hormone, pulse area and basal secretion and raised IGF-1, while insulin-stimulated glucose uptake did not change significantly (Stanley et al., 2011).

In a randomized, placebo-controlled trial in 412 adults with HIV and excess abdominal fat, visceral fat measured by CT fell 15.2% over 26 weeks against a 5.0% rise with placebo (Falutz et al., 2007). Models: plasma in vitro, pigs, rats, dogs, healthy men and a randomized trial. The tesamorelin research guide covers the rest of its literature.

Ipamorelin

Ipamorelin, Aib-His-D-2-Nal-D-Phe-Lys-NH2, was described in 1998 as the first selective growth hormone secretagogue. It released growth hormone from primary rat pituitary cells with potency similar to GHRP-6, acted through a GHRP-like receptor rather than the GHRH receptor, and in conscious swine did not raise ACTH or cortisol above the levels seen with GHRH, while GHRP-6 and GHRP-2 did (Raun et al., 1998). The endogenous ligand of that receptor was identified the next year as ghrelin (Kojima et al., 1999).

In healthy male volunteers, ipamorelin showed kinetics proportional to the amount given, a terminal half-life of about two hours and a single episode of growth hormone release peaking near 40 minutes (Gobburu et al., 1999). A phase 2 placebo-controlled trial in 114 adults after bowel resection found it well tolerated but not significantly different from placebo on its key efficacy endpoint (Beck et al., 2014). Models: rat pituitary cells, rats, swine, healthy volunteers and a phase 2 trial. The ipamorelin research guide has the full picture.

Why the two classes are paired

The case for pairing a GHRH analog with a secretagogue comes from older studies that used neither of these compounds. In rat primary pituitary cell culture, the hexapeptide GHRP-6 and growth hormone-releasing factor at maximal concentrations had a synergistic effect on growth hormone release; GHRP-6 did not raise intracellular cyclic AMP while the releasing factor raised it about three fold, and the authors concluded that the two act through different receptors (Cheng et al., 1989).

In 18 healthy men, submaximal amounts of the same hexapeptide given with GHRH(1-44) released growth hormone synergistically (Bowers et al., 1990). Models: rat cell culture and healthy men. Whether tesamorelin and ipamorelin interact the same way has not been tested.

No published study has tested tesamorelin and ipamorelin together, in any model. A PubMed search in October 2026 returned only review articles that discuss both compounds among other peptides, none reporting combined data (for example Mayfield et al., 2026). There are no data on how the two behave together in solution, on the stability of the mixed material, or on any combined effect, and their reported half-lives come from different species and settings. Studies using this material should handle it as a defined mixture and include controls for each component.