What is the equivalent dose of Saxenda (liraglutide) when switching from Zepbound (tirzepatide) 15 mg Subcutaneously (SC) every week?

Dose Equivalent When Switching from Zepbound 15 mg SC Weekly to Saxenda

When switching from Zepbound (tirzepatide) 15 mg SC weekly to Saxenda (liraglutide), patients should be initiated on Saxenda at 0.6 mg daily with weekly dose escalation to the maximum dose of 3.0 mg daily to maintain weight loss efficacy.

Understanding the Medications

Tirzepatide (Zepbound)

• Dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist
• Weekly subcutaneous injection
• Maximum dose of 15 mg provides approximately 14.7% total body weight loss 1
• Longer half-life (5 days) 1

Liraglutide (Saxenda)

• GLP-1 receptor agonist only (not dual agonist)
• Daily subcutaneous injection
• Maximum dose of 3.0 mg provides approximately 6.0% total body weight loss 1
• Shorter half-life (13 hours) 1

Dosing Protocol for Transition

1. Initial Dose: Start with Saxenda 0.6 mg SC daily
2. Titration Schedule: Increase by 0.6 mg weekly as tolerated
   • Week 1: 0.6 mg daily
   • Week 2: 1.2 mg daily
   • Week 3: 1.8 mg daily
   • Week 4: 2.4 mg daily
   • Week 5: 3.0 mg daily (maintenance dose)

Important Clinical Considerations

Efficacy Differences

• Patients should be informed that tirzepatide 15 mg produces significantly greater weight loss than liraglutide 3.0 mg (14.7% vs 6.0%) 1
• Recent comparative studies show tirzepatide is superior to other GLP-1 receptor agonists for weight loss 2, 3
• Expect reduced efficacy when switching from tirzepatide to liraglutide

Timing of Transition

• Consider initiating Saxenda on the day the next Zepbound dose would be due
• Due to tirzepatide's long half-life (5 days), there will be overlapping effects during transition 1

Side Effect Management

• Both medications have similar side effect profiles, primarily gastrointestinal
• Common side effects include nausea, vomiting, diarrhea, and constipation 1
• Slower dose titration may help manage GI side effects 1
• Monitor for potential psychiatric adverse events (rare but reported with both medications) 4

Monitoring Recommendations

• Evaluate efficacy at 16 weeks after reaching the 3.0 mg dose
• According to guidelines, Saxenda should be discontinued if 4% weight loss is not achieved at 16 weeks 1
• Monitor for gallbladder-related disorders and pancreatitis with both medications 1

Common Pitfalls to Avoid

1. Skipping titration: Do not start directly at 3.0 mg of Saxenda, as this will likely cause severe gastrointestinal side effects
2. Unrealistic expectations: Inform patients that weight regain is possible when switching from tirzepatide to liraglutide due to differences in potency
3. Inadequate monitoring: Failure to assess efficacy at 16 weeks may result in unnecessary continuation of an ineffective medication
4. Medication interactions: Be aware of potential delayed absorption of oral medications with narrow therapeutic indices like warfarin 1

The transition from Zepbound to Saxenda requires careful dose titration and management of patient expectations regarding differences in weight loss efficacy between these medications.