Retatrutide
Complete Research Guide
Open each section for the available evidence. Gaps are stated rather than inferred.
Overview
Retatrutide is listed as metabolic / triple agonist (glp-1 + gip + glucagon).
- •Obesity
- •Type 2 Diabetes (investigational)
Regulatory status: Investigational (Eli Lilly, Phase 3 TRIUMPH program).
Structure & Properties
Compound: Retatrutide; also known as LY3437943.
Pharmacologic class: Metabolic / Triple Agonist (GLP-1 + GIP + Glucagon).
Known delivery routes: Subcutaneous.
Sequence, molecular weight, salt form, and excipient details are formulation-specific and are not listed unless verified by a manufacturer or laboratory COA.
How It Works
Triple agonist of GLP-1, GIP and glucagon receptors — combines appetite suppression and insulin sensitization with glucagon-driven energy expenditure.
- •Largest weight loss seen in GLP-1-class trials
- •Improved glycemic and lipid profile
- •Reduced hepatic steatosis
Human Research
Evidence grade: Clinical RCT (Limited)
Clinical RCT (Limited). Phase 3 ongoing; Phase 2 showed up to ~24% weight loss at 48 wk.
Laboratory Research
Phase 3 ongoing; Phase 2 showed up to ~24% weight loss at 48 wk
Preclinical findings describe biological plausibility, not proven benefit in people. Animal and laboratory doses do not translate directly to human use.
Processing & Interactions
Timing and exposure
Once weekly, any time of day, with or without food.
Potential interactions and combinations to avoid
- •All other GLP-1 / GIP / glucagon agonists
- •MTC/MEN2 history
Absorption, half-life, metabolism, and clearance can vary by formulation and route. Use prescribing information when an approved product exists.
Safety & Precautions
Known or reported risks
- •GI side effects (nausea, vomiting)
- •Heart rate increase
- •Unknown long-term safety
Contraindications
- •MTC / MEN-2 (class)
- •Pregnancy
- •Severe gastroparesis
- •Personal or family history of medullary thyroid carcinoma or MEN-2 syndrome
- •History of pancreatitis or unexplained elevated lipase/amylase
- •Gastroparesis, severe GERD, or chronic gastrointestinal motility disorder
- •History of symptomatic gallstones or biliary disease
- •Active eating disorder, malnutrition, or BMI already in the underweight range
- •Type 1 diabetes as monotherapy for glycemic control
- •Planned surgery/anesthesia without pre-procedure fasting adjustment (aspiration risk)
- •Proliferative diabetic retinopathy with rapid glycemic lowering
- •Severe renal impairment with ongoing dehydration or vomiting
- •Bleeding disorders or anticoagulant therapy without physician guidance (injection-site haematoma)
- •Active skin infection, cellulitis, or lipohypertrophy at intended injection sites
- •Inability to maintain sterile technique or safe sharps disposal
- •Not FDA-approved for human therapeutic use — no verified purity, sterility, or potency standards
- •Immunocompromised or transplant patients (unverified sterility and immunogenicity risk)
- •Concurrent participation in drug-tested sport (WADA prohibited or non-cleared substance)
- •Known hypersensitivity or prior reaction to this compound or any excipient/diluent
- •Pregnancy, attempting conception, or breastfeeding unless prescribed and monitored by a physician
- •Children and adolescents with open growth plates (unless under specialist endocrine care)
- •Active or recently treated malignancy without oncology clearance
- •Use without a confirmed diagnosis, baseline labs, and licensed clinical supervision
Unknown long-term toxicity should be assumed where controlled human data are limited. Seek urgent care for a severe or unexpected reaction.
Administration & Studied Formulations
Reference range: 1–12 mg/week (trial doses)
Frequency: Weekly
Cycling: Continuous with monthly titration in trials.
Subcutaneous (SubQ)
Default route for most research and therapeutic peptides — best absorption for reconstituted powder.
31G × 5/16" insulin syringe (U-100). 100 units = 1 mL. Pinch skin at abdomen (2" from navel), outer thigh, or love handle. Insert at 45–90°. Rotate sites daily to prevent lipohypertrophy. Alcohol-swab site, air-dry, inject slow, hold 5 sec.
Dosing information is educational context, not a personal recommendation. Approved products must follow their label and prescriber instructions.
Applications & Related Therapies
Potentially complementary measures
- •Structured nutrition and resistance training to preserve lean mass
Clinical use should account for diagnosis, approved alternatives, nutrition, activity, sleep, rehabilitation, current medicines, and appropriate monitoring.
Cases, Considerations & Ethics
Decision framework: establish the clinical goal, confirm evidence quality and legal status, screen contraindications and interactions, compare approved alternatives, define monitoring and stopping criteria, and use shared decision-making with a licensed clinician.
Case evidence: individual reports cannot establish safety or effectiveness and should not outweigh controlled trials.
Ethics: informed consent should distinguish established care from experimental use, disclose uncertainty and cost, avoid overstated claims, and never substitute research products for medically necessary care.
Function
Dosing
Recommended Time of Day
Same day each week, any time of day.
See “Timing & Interactions” below for full fasted/fed circumstances, what to avoid combining, and what pairs well.
Administration & Technique
Injection & Application Sites
- Abdomen — 2 in (5 cm) away from the navel, either side. Fastest, most consistent SubQ absorption.
- Flank / love handle — Lateral fat pad above the hip. Good rotation site when the abdomen is tender.
- Outer thigh — Upper outer quadrant, a hand-width below the hip. SubQ pinch at 45°.
Diagram is a general illustration, not a medical instruction. Rotate sites every injection, keep 1 in (2.5 cm) between recent sites, and avoid scars, moles, bruises and the navel area.
Cycling
Continuous with monthly titration in trials.
Timing & Interactions
- ·All other GLP-1 / GIP / glucagon agonists
- ·MTC/MEN2 history
- ·Structured nutrition and resistance training to preserve lean mass
Storage & Reconstitution
Reconstitution Calculator
1 mL = 100 units on a standard U-100 insulin syringe. Draw to the nearest 0.5 unit and confirm dosing with a clinician before injection.
Your Notes
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Benefits
- ·Largest weight loss seen in GLP-1-class trials
- ·Improved glycemic and lipid profile
- ·Reduced hepatic steatosis
Risks
- ·GI side effects (nausea, vomiting)
- ·Heart rate increase
- ·Unknown long-term safety
Contraindications
- ·MTC / MEN-2 (class)
- ·Pregnancy
- ·Severe gastroparesis
- ·Personal or family history of medullary thyroid carcinoma or MEN-2 syndrome
- ·History of pancreatitis or unexplained elevated lipase/amylase
- ·Gastroparesis, severe GERD, or chronic gastrointestinal motility disorder
- ·History of symptomatic gallstones or biliary disease
- ·Active eating disorder, malnutrition, or BMI already in the underweight range
- ·Type 1 diabetes as monotherapy for glycemic control
- ·Planned surgery/anesthesia without pre-procedure fasting adjustment (aspiration risk)
- ·Proliferative diabetic retinopathy with rapid glycemic lowering
- ·Severe renal impairment with ongoing dehydration or vomiting
- ·Bleeding disorders or anticoagulant therapy without physician guidance (injection-site haematoma)
- ·Active skin infection, cellulitis, or lipohypertrophy at intended injection sites
- ·Inability to maintain sterile technique or safe sharps disposal
- ·Not FDA-approved for human therapeutic use — no verified purity, sterility, or potency standards
- ·Immunocompromised or transplant patients (unverified sterility and immunogenicity risk)
- ·Concurrent participation in drug-tested sport (WADA prohibited or non-cleared substance)
- ·Known hypersensitivity or prior reaction to this compound or any excipient/diluent
- ·Pregnancy, attempting conception, or breastfeeding unless prescribed and monitored by a physician
- ·Children and adolescents with open growth plates (unless under specialist endocrine care)
- ·Active or recently treated malignancy without oncology clearance
- ·Use without a confirmed diagnosis, baseline labs, and licensed clinical supervision
Regulatory
Investigational (Eli Lilly, Phase 3 TRIUMPH program)
Veterinary Use (Pets)
No established veterinary protocol for Retatrutide. Consult a licensed veterinarian before considering off-label use in any species.
Full veterinary reference →Functional Groups
Cited Works
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