Can a patient take half of a dose of Mounjaro (tirzepatide) using the applicator?

Mounjaro Pen Cannot Be Used to Administer Partial Doses

No, a patient cannot take half of a dose of Mounjaro using the applicator—the pen is a single-dose, pre-filled device that delivers a fixed dose and does not have adjustable clicks or mechanisms to administer partial doses. 1, 2

Device Design and Administration

• Mounjaro comes as single-dose prefilled pens that are designed to deliver the complete prescribed dose in one injection 3
• The pen is a fixed-dose delivery system without adjustable dosing mechanisms or "clicks" that would allow for partial dose administration 1
• Each pen contains a specific dose (2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, or 15 mg) and must be used as a complete unit 1

Why Dose Splitting Is Not Appropriate

• The FDA-approved titration schedule requires starting at 2.5 mg weekly for the first 4 weeks specifically to minimize gastrointestinal side effects, then escalating by 2.5 mg every 4 weeks 1
• This gradual titration is essential to minimize gastrointestinal adverse effects, which are common with GLP-1 receptor agonists and dual GIP/GLP-1 receptor agonists 2
• Attempting to split doses would bypass the carefully designed titration protocol that balances efficacy with tolerability 1

Correct Dosing Approach

• If a patient experiences intolerable side effects at a given dose, the appropriate response is to remain at the current dose for an additional 4 weeks before attempting to escalate, rather than attempting to split doses 1
• If gastrointestinal side effects are severe, counsel patients to eat smaller portions during the titration phase and reassure them that nausea is typically self-limited 2
• If treatment must be suspended and restarted, begin again at 2.5 mg with gradual up-titration to avoid recurrent symptoms 2

Common Pitfall to Avoid

• Do not attempt to extract partial doses from the pen using syringes or other methods—this would be off-label use, potentially unsafe, and would compromise the sterility and accuracy of dosing 1
• The initial 2.5 mg dose is not a "half dose" but rather the FDA-approved starting dose designed for treatment initiation 1