Tesamorelin + CJC-1295 (No DAC)

The shared receptor

Both components are agonists at the GHRH receptor, a class B G protein-coupled receptor expressed on pituitary somatotrophs. Receptor engagement couples through Gs to adenylyl cyclase, raising intracellular cAMP, activating protein kinase A and driving both the release of stored growth hormone and transcription of the GH gene. Because the two peptides converge on this one pathway, their effects in a preparation are not additive in the way a GHRH-plus-ghrelin-receptor combination would be — a point that matters when designing controls.

Tesamorelin: stabilising the full sequence

CJC-1295 no DAC: truncating and substituting

• Residues 1–29 retain essentially full GHRH-receptor activity, so the C-terminal region can be removed without losing potency
• D-Ala at position 2 blocks DPP-4 cleavage, the same liability tesamorelin addresses by acylation
• Gln8 removes an asparagine deamidation site; Ala15 and Leu27 address trypsin cleavage and methionine oxidation respectively
• Omitting the drug affinity complex means no covalent albumin binding, so circulating persistence is short compared with the DAC version

Why researchers combine them

A vial containing two agonists of one receptor is most useful as a comparative and formulation tool. Investigators have used such preparations to examine how differently stabilised analogues behave in the same solution — relative solubility, co-lyophilization behaviour, aggregation, and stability under identical storage conditions — and to model receptor occupancy when two ligands of different size and half-life compete for the same binding site. Any interpretation of pituitary output from a mixed preparation requires single-agent controls, since the shared pathway saturates.

Allow the vial to reach room temperature before breaking the seal, so condensation does not settle on the cake. Reconstitute with bacteriostatic or sterile water added slowly down the inner wall, then swirl gently until clear — never shake, as agitation shears peptide chains and foams the solution. Because the two components are co-lyophilized in a fixed 2:1 mass ratio, every withdrawn aliquot carries both peptides in that proportion; record the total peptide mass and the ratio when calculating working concentrations. Store the sealed powder at −20 °C and reconstituted solution at 2–8 °C, protected from light. Log lot number, reconstitution date, diluent and volume, and discard any solution that turns cloudy or shows particulates.