Retatrutide vs Teriparatide
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Retatrutide
Retatrutide (LY3437943) is a first-in-class triple agonist peptide targeting GIP, GLP-1, and glucagon receptors simultaneously. Developed by Eli Lilly, it is currently in Phase 3 clinical trials and has demonstrated the highest weight loss of any obesity medication to date — up to 28.7% body weight reduction at 48 weeks. The triple-receptor mechanism represents the next evolution beyond dual agonists like tirzepatide.
Full details →Teriparatide
Teriparatide (Forteo) is recombinant human parathyroid hormone (1-34), FDA-approved for osteoporosis treatment. It's unique among osteoporosis drugs in that it stimulates new bone formation.
Full details →Side-by-Side Comparison
| Aspect | Retatrutide | Teriparatide |
|---|---|---|
| Mechanism | Retatrutide is a synthetic peptide that activates three incretin/metabolic hormone receptors: (1) GLP-1 receptor — appetite suppression, insulin secretion, delayed gastric emptying, (2) GIP receptor — enhanced insulin sensitivity, improved fat metabolism, (3) Glucagon receptor — increased energy expenditure, hepatic fat mobilization, thermogenesis. The glucagon receptor component is the key differentiator, adding an energy-expenditure mechanism absent from GLP-1 and dual GIP/GLP-1 agonists. The molecule uses a C20 fatty diacid for albumin binding, enabling once-weekly dosing. | Intermittent PTH exposure paradoxically stimulates osteoblasts more than osteoclasts, resulting in net bone formation. Continuous exposure would cause bone loss, but pulsatile dosing builds bone. |
| Typical Dosage | Phase 2 trial doses: 0.5 mg, 4 mg, 8 mg, and 12 mg weekly. The 12 mg dose produced maximum weight loss (28.7%). Phase 3 trials are evaluating doses up to 12 mg. Dose escalation schedule similar to other GLP-1s (start low, increase every 4 weeks). Final approved dosing not yet established — Phase 3 trials ongoing. | 20mcg subcutaneously once daily. Maximum treatment duration of 2 years due to theoretical osteosarcoma risk from rat studies. |
| Administration | Subcutaneous injection, once weekly. Phase 3 trials use pre-filled single-dose pens. Not yet commercially available — estimated FDA approval ~2027-2028. | Subcutaneous injection in thigh or abdomen once daily. Delivered via multi-dose pen. Should sit or lie down after injection due to orthostatic hypotension risk. |
| Side Effects | Phase 2 data: nausea (up to 25%), diarrhea (up to 22%), vomiting (up to 15%), constipation, decreased appetite. GI side effects were dose-dependent and generally mild-to-moderate. Lower rates of nausea compared to semaglutide, potentially due to GIP component. Increased heart rate observed at higher doses. | Orthostatic hypotension, leg cramps, nausea, dizziness, headache, and injection site reactions. Transient hypercalcemia possible. |
| Best For |
Key Differences
Unique to Retatrutide:
Unique to Teriparatide:
Detailed Analysis
Commonalities
Retatrutide and Teriparatide are used for different purposes and have limited overlap in their applications.
Which Should You Choose?
Choose Retatrutide for Fat Loss. Choose Teriparatide for Recovery & Healing.
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