Ordering a Three‑Month Supply of Mounjaro (Tirzepatide): Milliliter Calculation
To order a three‑month supply of Mounjaro, you need to calculate the total milliliters based on your prescribed weekly dose and the pen concentration. Each Mounjaro pen delivers a fixed dose per injection, and the total volume required depends on your maintenance dose (5 mg, 10 mg, or 15 mg weekly) over approximately 13 weeks.1
Understanding Mounjaro Pen Packaging
- Mounjaro is supplied as pre‑filled single‑dose pens that deliver a specific milligram dose per injection, not in multi‑dose vials measured in milliliters.1
- Each pen contains a fixed volume of solution designed to deliver one weekly dose—you inject the entire pen contents subcutaneously once per week.1
- The pens are available in five dose strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg per pen.1
Calculating a Three‑Month Supply
Step 1: Determine Your Weekly Maintenance Dose
- Tirzepatide is titrated gradually starting at 2.5 mg weekly for the first 4 weeks (tolerability phase), then increased to 5 mg weekly as the initial maintenance dose.12
- After at least 4 weeks on 5 mg, the dose may be escalated to 10 mg weekly, and after another 4 weeks to the maximum approved dose of 15 mg weekly if additional glycemic control or weight loss is needed.12
Step 2: Calculate Total Pens for 13 Weeks
- For a patient on 5 mg weekly maintenance: 13 weeks × 1 pen per week = 13 pens of 5 mg.1
- For a patient on 10 mg weekly maintenance: 13 weeks × 1 pen per week = 13 pens of 10 mg.1
- For a patient on 15 mg weekly maintenance: 13 weeks × 1 pen per week = 13 pens of 15 mg.1
Step 3: Milliliter Equivalents (If Required by Pharmacy)
- Each Mounjaro pen contains 0.5 mL of solution regardless of the dose strength; the concentration varies to deliver the prescribed milligram dose in that fixed volume.1
- For a three‑month supply at any maintenance dose: 13 pens × 0.5 mL per pen = 6.5 mL total volume.1
Practical Ordering Instructions
- Specify the dose strength and number of pens when ordering: for example, "Mounjaro 10 mg subcutaneous injection, dispense 13 pens for a 90‑day supply."1
- Insurance authorization typically requires documentation of BMI ≥30 kg/m² (or ≥27 kg/m² with weight‑related comorbidities such as type 2 diabetes or hypertension) and confirmation that the patient has been on the current dose for at least 4 weeks.23
- The average wholesale price for a 30‑day supply (approximately 4 pens) is $1,272, so a three‑month supply costs roughly $3,816 without insurance coverage.1
Titration Considerations for New Patients
If the patient is still in the dose‑escalation phase, a three‑month supply will include multiple dose strengths:
Patients who miss two consecutive doses should resume at the same dose if previously tolerated; if three or more doses are missed, consider restarting the titration schedule from 2.5 mg.2
Key Contraindications and Safety Checks Before Ordering
- Absolute contraindication: personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 (MEN 2)—screen all patients before prescribing.12
- Relative cautions: history of pancreatitis (causality not definitively established but warrants vigilance), symptomatic gallbladder disease (tirzepatide increases cholelithiasis risk by approximately 38% versus placebo), and severe gastroparesis.23
- Concomitant medication adjustments: reduce basal insulin by 20% and sulfonylureas by 50% (or discontinue) when starting tirzepatide to prevent hypoglycemia.2
Common Pitfalls to Avoid
- Do not order based on "units" or milliliters alone—Mounjaro pens are dosed in milligrams, and each pen delivers a fixed dose regardless of volume.1
- Do not assume all pens contain the same concentration—the 5 mg, 10 mg, and 15 mg pens each hold 0.5 mL but differ in drug concentration to deliver the prescribed dose.1
- Do not delay dose escalation beyond 4 weeks on a given dose if the patient tolerates it well and requires additional glycemic control or weight loss—early titration to therapeutic doses improves outcomes.24
- Do not prescribe a three‑month supply of the starting 2.5 mg dose—this dose is for tolerability assessment only, not for sustained efficacy.12
Summary Algorithm for Ordering
- Confirm the patient's current maintenance dose (5 mg, 10 mg, or 15 mg weekly).1
- Calculate 13 pens for a 90‑day supply at that dose strength.1
- Document the total volume as 6.5 mL if the pharmacy requires milliliter notation (13 pens × 0.5 mL per pen).1
- Verify insurance coverage and obtain prior authorization if needed, citing BMI criteria and comorbidities.23
- Educate the patient on weekly injection technique, missed‑dose management, and warning signs of pancreatitis or gallbladder disease.2