G3 - Research Grade 20mg

Retatrutide

• What is Retatrutide?

  Retatrutide (LY3437943) is a novel triple hormone receptor agonist targeting GLP-1, GIP, and glucagon receptors. Phase III TRIUMPH-4 trial (Dec
  2025) achieved 28.7% weight loss (71.2 Ibs) at 68 weeks with 12mg dose - the highest recorded for any obesity medication. Currently in late-stage Phase III development by Eli Lilly with FDA approval expected 2026-2027.

• Key Benefits

  Triple hormone receptor activation provides superior weight loss (24.2%), improved glycemic control, and enhanced cardiovascular benefits compared to single or dual agonists
  

• Mechanism of Action

  Activates GLP-1 for appetite suppression, GIP for insulin sensitivity, and glucagon for increased energy expenditure and hepatic fat oxidation

• Typical Dose

  Start 0.5mg weekly (clinical practice) or 1mg weekly (trial protocol), escalate every 4 weeks to target 8-12mg

• Frequency

  Once weekly

• Injection Sites

  Abdomen, thigh, upper arm - rotate weekly to prevent lipodystrophy

• Best Timing

  Any time of day, maintain same day each week for consistency

• Effects Timeline

  24-48 hours: appetite suppression; 4-8 weeks: significant weight loss; 24+ weeks:
  maximum benefits

• Storage

  Lyophilized powder at room temperature; reconstituted solution refrigerated

• Cycle Length

  Continuous therapy

• Molecular Information

  Molecular Weight
  4,731.33 Da
  Chain Length
  39 amino acids
  Amino Acid Sequence
  His-Aib-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-
  Ile-Ala-Trp-Leu-Val-Arg-Gly-Arg-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser

• Timing

  Administer on the same day each week for consistent hormone regulation. Can be taken with or without food due to subcutaneous administration.
  

• Research Protocols

  Research starts very low and increases gradually over time. It begins with a conservative starting dose of 0.5 mg weekly for weeks 1 to 4, then rises to 1 mg weekly for weeks 4 to 8, 2 mg weekly for weeks 8 to 12, 4 mg weekly for weeks 12 to 16, and 8 mg weekly for weeks 16 to 20. 12 mg weekly from week 20 onward as the maximum-efficacy dose. For type 2 diabetes, it suggests a more cautious approach, starting at 0.5 to 1 mg weekly.

• Research Indications

  Weight Loss - Most Effective

  
  Superior Weight Reduction
  Clinical trials demonstrate 17.5% at 24 weeks and 24.2% at 48 weeks - highest recorded for any obesity medication in development
  Sustained Weight Management
  Continuous weight loss throughout trials with no plateau reached at 48 weeks, suggesting greater long-term potential than current therapies
  Triple Mechanism Obesity Treatment
  Addresses obesity through appetite suppression, increased energy expenditure, and improved metabolic efficiency via three hormone pathways
  
  Diabetes - Effective
  Superior Glycemic Control
  HbA1c reductions up to 2.16% with 82% of participants achieving target levels below 6.5% - exceeding dual agonist performance
  Glucose-Dependent Regulation
  Glucose-dependent insulin secretion and glucagon suppression provide balanced glycemic control with minimal hypoglycemia risk

  
  Insulin Sensitivity Enhancement
  Marked improvements in insulin sensitivity with potential for significant reduction in exogenous insulin requirements
  

• What to Expect

  * Week 1-2: Initial appetite suppression and mild Gl effects as body adapts to triple hormone activation
  * Week 2-4: Noticeable reduction in food cravings and portion sizes, early weight loss (2-5%)
  * Week 4-8: Significant appetite control and steady weight loss (5-10%), improved glucose control if diabetic
  * Week 8-16: Substantial weight reduction (10-18%) with enhanced energy expenditure and metabolic improvements
  * Week 16-24: Major weight loss milestone (15-22%) with cardiovascular benefits and liver fat reduction
  * Week 24-48: Maximum clinical efficacy (20-24.2%) with comprehensive metabolic improvements and sustained benefits
  

• Side Effects & Safety

  - Most common side effects are gastrointestinal (nausea 43%, diarrhea 33% at 12mg) - typically mild to moderate and dose-dependent
  - NEW SIGNAL (Dec 2025): Dysesthesia (abnormal touch sensations) reported in 8.8-20.9% of participants at 9-12mg doses in TRIUMPH-4 trial
  - Conservative start at 0.5mg weekly minimizes Gl side effects (13% vs 73-94% at higher doses) - escalate gradually every 4 weeks
  - Phase III discontinuation rates: 12.2% (9mg) and 18.2% (12mg) due to adverse events - correlated with baseline BMI
  - Monitor for signs of pancreatitis (severe abdominal pain radiating to back) - discontinue immediately if suspected
Heart rate increases are common, especially in first 24 weeks - monitor cardiovascular status regularly
Contraindicated in patients with personal/family history of medullary thyroid carcinoma or MEN2
syndrome
May cause rapid weight loss - some discontinuations due to perceived excessive weight loss