Retatrutide

Retatrutide (LY3437943) is an investigational once-weekly triple agonist of the GLP-1, GIP and glucagon receptors, evaluated in Phase II trials for obesity and type 2 diabetes. It is not an approved drug in any jurisdiction.

GLP-1 receptor agonism slows gastric emptying and enhances glucose-dependent insulin secretion; GIP receptor agonism contributes additional insulinotropic and adipose tissue effects; glucagon receptor agonism increases energy expenditure and hepatic lipid oxidation. The combination produced the largest weight reductions reported for an incretin agent in Phase II.

Store the sealed lyophilized vial at 2-8 °C, protected from light; brief exposure to room temperature during shipping is generally tolerated. Refrigerate after reconstitution at 2-8 °C and use within the period supported by stability data for the substance (typically 2-4 weeks). Avoid repeated freeze-thaw cycles: each cycle increases the risk of aggregation and hydrolysis of the peptide bond. Do not shake the vial; swirl gently and direct the liquid stream against the glass wall rather than at the powder cake.

• Sealed lyophilized vial, stored as supplied
• Bacteriostatic water (0.9% benzyl alcohol) for reconstitution
• Insulin syringes (29-31G, 0.5 mL / 100 units)
• Reconstitution syringe (1-3 mL, 21-23G needle)
• 70% isopropyl alcohol swabs
• Sharps container for used needles
• Labels and a logbook for batch, date and volume

In a 48-week Phase II obesity trial, mean weight reduction reached approximately 24% at the highest dose. Adverse effects were predominantly gastrointestinal (nausea, vomiting, diarrhea, constipation) and dose-dependent, with dose escalation used to limit them. Increases in heart rate were observed. Long-term safety remains under investigation.

Wash your hands, then disinfect the vial septum and the injection site with 70% isopropyl alcohol and allow both to air dry. Draw up the intended volume, remove air bubbles and pinch a subcutaneous skin fold. Insert at a 45-90° angle depending on fat thickness, aspiration is not required for subcutaneous administration, and inject slowly. Withdraw the needle, apply light pressure and discard the needle in a sharps container. Rotate injection sites systematically (abdominal quadrants, flanks, thighs) to prevent lipohypertrophy and local irritation.

Peptide research protocols are studied against a background of adequate protein intake (approximately 1.6-2.2 g/kg/day in the training literature), consistent sleep of 7-9 hours, and controlled training load. Sleep deprivation and chronic psychological stress both dampen growth hormone pulsatility and disrupt tissue remodeling, complicating the interpretation of any observed effect. Alcohol, smoking and large caloric deficits are likewise documented modifiers of recovery outcomes.

1. Jastreboff A.M. et al. Triple-hormone-receptor agonist retatrutide for obesity: a Phase 2 trial. N Engl J Med, 2023.
2. Rosenstock J. et al. Retatrutide in type 2 diabetes: a Phase 2 trial. Lancet, 2023.
3. Coskun T. et al. LY3437943, a novel triple GIP/GLP-1/glucagon receptor agonist. Cell Metab, 2022.