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Understanding the dosing process for GLP-1 medications can be confusing, especially when you’re trying to balance units, milligrams, and vial concentrations. Many users make dosing errors simply due to rushing or misinterpreting these measurements. This dosing guide breaks down each essential element of dosing—from understanding vial volumes and concentrations to safely converting doses into syringe units. With careful, step-by-step instructions, you can ensure your doses are accurate and safe, helping you avoid common pitfalls that new users often encounter.

1. Volume in a Vial (mL)

• This is the total liquid volume inside the vial, measured in milliliters (mL).
• For example, a vial might contain 1.5mL or 3mL of liquid, which includes both the drug and any stabilizing solutions.
• This volume does not directly indicate the amount of medication, as it needs to be combined with the concentration to understand how much drug is in the vial.

2. Concentration of a Vial (mg/mL)

• Concentration refers to how much drug (measured in milligrams, or mg) is present per milliliter (mL) of solution.
• For example, if the concentration is 10mg/mL, each mL of solution contains 10mg of the active drug.
  • NOTE: if the concentration is listed per half mL, you will want to convert the calculation to per mL. For example, if the concentration is listed as 10mg/0.5mL, multiply the concentration by 2 to get a concentration of 20mg/mL. You will use the concentration per mL in the calculation below.
• If your vial has an additive such as niacinamide, the concentration may be displayed like “TIRZEPATIDE/NIACINAMIDE 8/2 mg/mL”. This can be read as a Tirzepatide concentration of 8mg/mL and Niacinamide concentration of 2mg/mL. The concentration of the additive can be disregarded when making your dosage calculation as your dosage instructions are based on the GLP-1 Medication only.

3. Total Drug in Vial (mg)

• To find the total drug in the vial, multiply the concentration by the volume. For instance, if a 3mL vial has a concentration of 10mg/mL, it contains a total of 3×10=30mg of drug.

4. Dose (mg)

• The dose is the amount of active drug given to the patient, typically specified in milligrams (mg).
• Doses are usually started at lower amounts (e.g., 2.5mg) and increased over time (e.g., up to 15mg) based on therapeutic need and tolerance.
• The dose is drawn from the vial according to the prescribed mg, which corresponds to a specific volume based on the vial’s concentration, see Dosing Calculation.

5. Units on the Syringe

• A U-100 syringe is a syringe calibrated specifically for insulin but can be used for other drugs when the dosing requires precision. In a U-100 syringe, each “unit” represents 0.01 mL.
• Thus, 100 units = 1 mL, and you would use this conversion to measure the liquid from the vial accurately.

Putting It All Together for Dosing Calculation with Syringe Units

To prepare a dose, you’ll need to calculate the volume to inject based on the concentration of the drug. For instance, suppose you have a GLP-1 medication vial with:

• A volume of 3 mL
• A concentration of 10mg/mL

If your prescribed dose is 5mg, you’d calculate the volume to draw as follows:

• To find the volume to draw from the vial (in mL), you can use this formula:
  • Dose/Concentration=Volume (mL)
  • Using our example:
    • 5/10=0.5mL
    • In other words, since 10mg is in each mL, you would need 0.5mL to get a 5mg dose.
• Converting volume to units on a U-100 syringe. To convert mL to units, use the conversion:
  • Volume (mL)×100=Units
  • In our example:
    • 0.5mLx100=50 units
    • So, you would draw 50 units on a U-100 syringe to get a 5mg dose of the GLP-1 medication if the concentration is 10mg/mL.

Some Additional Tips:

• Slow down! A lot of new users make mistakes because they’re moving faster than their brain is processing. Take a beat between steps and make sure you’re about to do the next step correctly.
• When opening a new vial, confirm the concentration and dosage. Don’t assume it’s the same as your last vial!
• Follow your provider/pharmacy’s dosing instructions. This is not an as-needed drug, don’t take an extra dose when you feel hungry.
• While it is okay to dose lower than the dosing protocols, especially for those with lower tolerance to side effects, it is NOT recommended to go beyond/higher/faster than the recommended dosing.
• Don’t use the same syringe for 2 vials. If there isn’t enough in your vial for your dose, draw up the remainder in the vial and then use a second syringe to draw the remainder of your dose from the new vial. Make sure the combined volume is your correct dosage.
• Don’t inject yourself if you’re not sure! Reach out to your provider or pharmacy for questions.
• CompoundPal can help you check your dose but it’s helpful to understand the units before you use their calculator.

I hope this dosing guide will help you on your GLP-1 journey. By taking the time to understand the basics of dosing and safe handling, you set yourself up for a successful GLP-1 treatment experience. Accuracy matters with each dose, and even small steps—like confirming the concentration or taking a moment to double-check measurements—can make a big difference. Remember, if you’re ever unsure, don’t hesitate to reach out to your provider or pharmacy for support. With patience and attention to detail, you can safely manage your medication and enjoy the benefits of this important treatment.