Retatrutide

Retatrutide (LY3437943) is a novel triple hormone receptor agonist targeting GLP-1, GIP, and glucagon receptors. Pivotal Phase III TRIUMPH-1 trial (May 2026) delivered 28.3% weight loss (70.3 lbs) at 80 weeks on 12mg, with a 104-week extension cohort reaching 30.3% (85.0 lbs). ADA 2026 data showed 60.6% AHI reduction in sleep apnea and 46% normoglycemia in TRANSCEND-T2D-1. Eli Lilly confirmed Q4 2026 NDA submission on the Q1 2026 earnings call; FDA approval realistically late 2027.

• Superior Weight Reduction
• Sustained Weight Management
• Triple Mechanism Obesity Treatment

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

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

Peak plasma concentration: 1 day. Elimination half-life: 6 days. Largely cleared by: ~30 days.

Research protocols from published literature — not dosing recommendations.

• Tirzepatide — Avoid Combination: Do not combine with other dual/triple agonists - risk of severe hypoglycemia, excessive gastrointestinal effects, and unpredictable hormone interactions
• Cagrilintide — Use Caution: Both cause significant GI effects (gastroparesis, nausea). Retatrutide (triple agonist) and Cagrilintide (amylin agonist) have different mechanisms but compounded GI side effects create substantial risk. Not recommended without specialist supervision.
• Semaglutide — Avoid Combination: Both act on the GLP-1 receptor. Combining them stacks effects on the same receptor pathway, increasing risk of severe nausea, gastroparesis, and hypoglycemia. No published safety data exists for this combination at any dose. If using both under clinical supervision, dose reductions and close monitoring are required.
• Insulin — Monitor Combination: May significantly reduce insulin requirements due to improved glucose control - monitor blood glucose closely and adjust insulin doses accordingly
• Metformin — Compatible: Safe combination tested in clinical trials with no significant interactions. Both work through different mechanisms to improve glucose control and weight management
• SGLT2 Inhibitors — Compatible: Clinical trials included participants on SGLT2 inhibitors with no safety concerns. Complementary mechanisms for glucose control
• Oral Contraceptives — Requires Timing: Space oral contraceptives by 1 hour before retatrutide injection due to delayed gastric emptying effects
• Warfarin — Monitor Combination: Weight loss may affect warfarin requirements - monitor INR more frequently and adjust anticoagulation as needed
• BPC-157 — Compatible: Safe combination - different therapeutic targets. BPC-157 promotes tissue repair via growth factors while Retatrutide targets metabolic hormone receptors. BPC-157 may provide GI protective benefits during Retatrutide use.
• NAD+ — Compatible: Safe combination - different cellular systems. Retatrutide targets hormone receptors (GLP-1/GIP/glucagon) while NAD+ supports cellular energy and DNA repair. NAD+ may support metabolic adaptation during weight loss.

Supplies:

• Sterile bacteriostatic water for injection
• Lyophilized Retatrutide vial
• Insulin syringes (0.3-1mL capacity)
• Alcohol swabs for sterilization
• Sharps disposal container

1. 1Remove Retatrutide vial from refrigeration and allow to reach room temperature (15-20 minutes)
2. 2Clean vial top with alcohol swab and allow to air dry completely
3. 3Add calculated amount of bacteriostatic water slowly down the side of the vial to minimize foaming
4. 4Gently swirl the vial in circular motions - DO NOT shake vigorously as this may damage the peptide structure
5. 5Allow to fully dissolve (may take 2-3 minutes) - solution should be clear and colorless
6. 6Store reconstituted solution in refrigerator (2-8°C) and use within 28 days
7. 7Draw calculated dose using insulin syringe, inject subcutaneously into abdomen, thigh, or upper arm
8. 8Rotate injection sites weekly to prevent lipodystrophy and maintain absorption consistency

Week 1-2: Initial appetite suppression and mild GI 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.

Most common side effects are gastrointestinal (nausea 43%, diarrhea 33% at 12mg) - typically mild to moderate and dose-dependent. Dysesthesia (abnormal touch sensations) confirmed across two Phase III trials: TRIUMPH-1 (May 2026) reported 5.1% / 12.3% / 12.5% at 4/9/12mg vs. 0.9% placebo, lower than the 8.8-20.9% range first seen in TRIUMPH-4. Signal is reproducible across studies, suggesting a class-level effect requiring labeling attention.. Conservative start at 0.5mg weekly minimizes GI side effects (13% vs 73-94% at higher doses) - escalate gradually every 4 weeks. Phase III discontinuation rates due to adverse events: TRIUMPH-1 at 4.1% / 6.9% / 11.3% (4/9/12mg) vs. 4.9% placebo; TRIUMPH-4 ran higher (12-18%) likely reflecting the older osteoarthritis population. 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.

Most common side effects are gastrointestinal (nausea 43%, diarrhea 33% at 12mg) - typically mild to moderate and dose-dependent. Dysesthesia (abnormal touch sensations) confirmed across two Phase III trials: TRIUMPH-1 (May 2026) reported 5.1% / 12.3% / 12.5% at 4/9/12mg vs. 0.9% placebo, lower than the 8.8-20.9% range first seen in TRIUMPH-4. Signal is reproducible across studies, suggesting a class-level effect requiring labeling attention.. Conservative start at 0.5mg weekly minimizes GI side effects (13% vs 73-94% at higher doses) - escalate gradually every 4 weeks. Phase III discontinuation rates due to adverse events: TRIUMPH-1 at 4.1% / 6.9% / 11.3% (4/9/12mg) vs. 4.9% placebo; TRIUMPH-4 ran higher (12-18%) likely reflecting the older osteoarthritis population. 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.

Retatrutide should be stored at Lyophilized powder at room temperature; reconstituted solution refrigerated.