How to Reconstitute Tesamorelin: Complete Step-by-Step Laboratory Guide Tesamorelin (MW 5135.9 g/mol, CAS 218949-48-9) is a stabilised synthetic GHRH analogue incorporating a trans-3-hexenoic acid modification at the N-terminus that confers enhanced proteolytic stability while preserving full GHRH-R binding capacity. It is supplied as a lyophilised white powder in a 10mL sterile glass vial containing 5mg of peptide. As a full GHRH-R agonist with improved stability relative to native GHRH, tesamorelin is used in pituitary somatotroph cell model research and hepatocyte GH axis signalling studies. Materials Required Tesamorelin 5mg lyophilised vial Bacteriostatic water (BAC water) — 10mL vial 1mL sterile syringe with needle Alcohol swabs (70% isopropyl) Nitrile gloves Permanent marker for labelling Refrigerator at 2–8°C for storage Pre-Reconstitution Preparation Inspect the tesamorelin vial to confirm the lyophilised powder appears white to off-white and intact with a secure seal. Remove from cold storage and allow to equilibrate to room temperature for 15 minutes. Tesamorelin's relatively large molecular weight (5135.9 g/mol) and N-terminal modification make the room temperature equilibration step beneficial for ensuring complete, even dissolution during the reconstitution procedure. Step-by-Step Reconstitution Protocol Step 1 — Prepare workspace. Wipe the work surface with 70% isopropyl alcohol and allow to dry completely. Wear nitrile gloves throughout. Step 2 — Swab both stoppers. Clean rubber stoppers on both vials with separate fresh alcohol swabs. Air dry 10–15 seconds each. Step 3 — Draw 2mL of BAC water. Draw 2mL of bacteriostatic water into a sterile syringe. Step 4 — Inject slowly along the vial wall. Insert the needle into the tesamorelin vial and direct the BAC water slowly down the inner glass wall over 15–20 seconds. Tesamorelin's N-terminal trans-3-hexenoic acid modification introduces a degree of hydrophobicity — directing the solvent along the wall rather than onto the powder reduces surface tension effects during dissolution. Step 5 — Dissolve by gentle rolling and swirling. Gently roll the vial between palms and swirl slowly for 60–90 seconds. Tesamorelin dissolves well in aqueous media but may require slightly more time than smaller peptides due to its molecular weight. The final solution should be clear and colourless. Do not shake or vortex. Step 6 — Inspect for clarity. Confirm the solution is fully clear with no visible particles before use or storage. Step 7 — Label vial. Record reconstitution date, concentration, and initials. Note the 28-day expiry. Resulting Concentration Adding 2mL BAC water to a 5mg tesamorelin vial yields a stock concentration of 2.5mg/mL (2500mcg/mL). For GHRH-R binding assays and cAMP pathway studies in GH3 and pituitary cell model preparations, working concentrations of 0.1nM–100nM are prepared by serial dilution into assay buffer or serum-free media immediately before use. Concentration Reference Table BAC Water Volume AddedResulting Concentration 1mL5.0mg/mL (5000mcg/mL) 2mL2.5mg/mL (2500mcg/mL) 5mL1.0mg/mL (1000mcg/mL) Storage Conditions and Stability Store lyophilised tesamorelin at −20°C prior to reconstitution, protected from light and moisture. Once reconstituted, store at 2–8°C. Reconstituted tesamorelin in BAC water is stable for up to 28 days under refrigeration. Do not freeze reconstituted solution. The N-terminal trans-3-hexenoic acid modification significantly extends tesamorelin's proteolytic stability relative to native GHRH and sermorelin in serum-containing conditions — this stability advantage simplifies cell model assay design by reducing the need for DPP-IV inhibitor supplementation in standard serum-containing media protocols. Research Application Notes Tesamorelin's enhanced proteolytic stability makes it particularly suitable for cell model assays requiring prolonged GHRH-R stimulation in serum-containing media, where native GHRH analogues would require DPP-IV inhibitor co-treatment to maintain compound integrity. In comparative GHRH-R pharmacology studies alongside sermorelin and CJC-1295 variants, tesamorelin provides a pharmacokinetically distinct reference point — full agonist activity with extended half-life but without the albumin-binding depot mechanism of CJC-1295 DAC. For hepatocyte GH axis research in HepG2 or primary human hepatocyte cell models, ensure working dilutions are prepared in serum-free HBSS or defined media immediately before assay to avoid compound sequestration by albumin. Tesamorelin 5mg vials are available from Pinnacle Peptides, verified at ≥99% purity by HPLC and mass spectrometry. All content is intended for in vitro laboratory research purposes only. Not for human or animal consumption. Not intended to diagnose, treat, cure, or prevent any condition.