Executive Summary
The landscape of metabolic therapeutics is shifting from single-hormone receptor agonism to multi-receptor synergy. While Semaglutide established the paradigm of potent GLP-1 efficacy, Tirzepatide demonstrated the superiority of dual GIP/GLP-1 agonism. The investigational triple agonist Retatrutide (GLP-1/GIP/Glucagon) represents the next frontier, potentially offering bariatric-surgery-mimicking weight loss, though safety signals regarding heart rate and glucagon-mediated effects remain under scrutiny in Phase 3 trials.
Semaglutide
Ozempic, Wegovy
Tirzepatide
Mounjaro, Zepbound
Retatrutide
LY3437943
Quick Comparison Matrix
| Feature | Semaglutide | Tirzepatide | Retatrutide |
|---|---|---|---|
| Route & Freq | Subcutaneous, Weekly | Subcutaneous, Weekly | Subcutaneous, Weekly |
| Target Receptors | GLP-1 | GLP-1, GIP | GLP-1, GIP, Glucagon |
| HbA1c Reduction | ~1.8 - 2.0% | ~2.0 - 2.3% | ~2.0 - 2.2% (Ph2) |
| Liver Fat Reduction | Moderate | High | Very High (>80% mean red.) |
Mechanism & Physiology
Understanding the "synergy" of multi-receptor agonism. Click a drug below to visualize its receptor profile and predicted physiological effects.
Physiological Impact
Select a drug to see its mechanism.
Incretin
- Increases insulin secretion (glucose-dependent)
- Slows gastric emptying
- Promotes satiety (CNS)
Incretin
- Increases insulin secretion
- Improves lipid buffering
- Potentiates GLP-1 efficacy (Synergy)
Glucagon
- Increases Energy Expenditure
- Mobilizes liver fat
- Historically linked to hyperglycemia (but balanced by GLP-1/GIP)
Clinical Efficacy Data
Head-to-head cross-trial comparison of weight loss and metabolic parameters. Note: Direct head-to-head trials between Retatrutide and Tirzepatide are not yet completed.
Mean Body Weight Reduction (%)
Note on Comparisons: Data sourced from separate pivotal trials (STEP 1, SURMOUNT-1, Retatrutide Phase 2). Populations may differ slightly in baseline BMI and demographics. Retatrutide data is from Phase 2 (48 weeks), others from Phase 3 (68-72 weeks).
Semaglutide has proven CV benefit (SELECT). Tirzepatide & Retatrutide outcome trials are ongoing.
All improve lipids. Retatrutide may have distinct effects on LDL/Triglycerides via glucagon.
Safety & Tolerability Profile
While GI side effects are common across the class, Retatrutide introduces new safety signals related to its glucagon activity that require monitoring.
Common GI Adverse Events (Nausea/Vomiting)
Percentage of participants reporting events during escalation. Most events are mild-to-moderate and transient.
Retatrutide Specific Signals
- ♥ Heart Rate: Dose-dependent increase in heart rate (peak +5-10 bpm) observed in Phase 2. Mechanisms likely linked to glucagon receptor chronotropy. Requires long-term CV safety data.
- ⚡ Cutaneous Hyperesthesia: Increased skin sensitivity (tenderness, burning sensation) reported by ~7% of patients at higher doses. Generally mild, but unique to this agent among incretins.
Class Warnings (All Agents)
Regulatory Status & Timeline
Current approval status and projected milestones. Dates for Retatrutide are estimates based on standard clinical trial timelines.