About

This guide supports the use of the Norditropin® dose calculator, a tool designed for healthcare professionals to accurately convert a prescribed dose of somatropin into the corresponding number of clicks for the Norditropin FlexPro® pen. Accurate dose conversion is critical for ensuring patient adherence and achieving therapeutic goals in growth hormone therapy.

Outputs

The calculator provides three primary outputs after inputs are entered:

• Clicks per Day: The number of clicks to set the FlexPro® pen to for each daily administration. This value is rounded to the nearest whole click.
• Actual Administered Dose: The precise dose in milligrams (mg) the patient will receive based on the rounded number of clicks. This may differ slightly from the mathematically calculated target dose.
• Pen Duration: An estimate of how many days one pen will last based on the actual administered dose, helping with supply management and prescription planning.

How to use

To use the calculator effectively, follow these steps:

1. Select Patient Indication: Choose the appropriate FDA-approved indication from the dropdown menu (e.g., Pediatric GHD, Turner Syndrome).
2. Enter Patient Weight: Input the patient's current weight and select the unit (kg or lbs).
3. Choose Dose Regimen: Select either a weight-based dose (mg/kg/day or mg/kg/week) or a fixed dose (mg/day).
4. Input Prescribed Dose: Enter the numerical value of the prescribed dose corresponding to the selected regimen.
5. Select Norditropin® Pen: Choose the correct pen strength (5, 10, 15, or 30 mg) that has been prescribed for the patient.

Dosing overview

Norditropin® dosing is individualized based on the indication. The following are typical weight-based dosing ranges as per the prescribing information:

• Pediatric Growth Hormone Deficiency (GHD): 0.024 to 0.034 mg/kg/day
• Turner Syndrome: Up to 0.067 mg/kg/day
• Noonan Syndrome: Up to 0.066 mg/kg/day
• Small for Gestational Age (SGA): Up to 0.067 mg/kg/day
• SHOX Deficiency: 0.045 to 0.050 mg/kg/day
• Idiopathic Short Stature (ISS): Up to 0.067 mg/kg/day
• Adult GHD: Dosing for both adult-onset and childhood-onset GHD is highly individualized. It typically starts with a low dose (e.g., 0.15-0.3 mg/day) and is titrated based on clinical response and serum IGF-1 concentrations.

The calculator will issue a clinical note if a weight-based dose falls outside these common ranges, prompting verification.

Switching

Switching a patient from another somatropin product to Norditropin®, or vice versa, should be done under the supervision of an experienced physician. While the active ingredient is the same, differences in formulation or delivery devices may warrant a period of clinical monitoring. Do not use this calculator for other brands of growth hormone, as pen mechanics and concentrations differ.

Missed dose

If a dose of Norditropin® is missed, it should be administered as soon as it is remembered. However, if it is almost time for the next dose, the missed dose should be skipped. Patients should be instructed not to administer a double dose to make up for a missed one and to resume their regular once-daily administration schedule.

Safety alerts

FAQ

Why is the "Actual Administered Dose" different from the target dose?

The FlexPro® pen delivers medication in discrete increments (clicks). The calculator rounds the required dose to the nearest whole click, which can result in a final administered dose that is slightly higher or lower than the ideal mathematical target.

What do the different pen colors signify?

The colors correspond to different strengths and concentrations of Norditropin®: Orange (5 mg/1.5 mL), Blue (10 mg/1.5 mL), Green (15 mg/1.5 mL), and Purple (30 mg/3.0 mL).

Can I use this calculator for other growth hormone pens?

No. This tool is specifically calibrated for the concentrations and click volumes of the Norditropin FlexPro® pens. Using it for other products like Genotropin, Humatrope, or Saizen will result in incorrect dosing.

Why does the 30 mg (Purple) pen have a different click volume?

The 30 mg pen has a total volume of 3.0 mL and is designed to deliver larger doses more efficiently. Each click from the 30 mg pen delivers 0.0250 mL, whereas the 5, 10, and 15 mg pens deliver 0.0125 mL per click.

The calculator showed a "Clinical Note" warning. What should I do?

This note appears when the entered weight-based dose is outside the typical range for the selected indication. You should verify the prescribed dose against the patient's records and official clinical guidelines.

How do I enter a weekly dose?

For weight-based dosing, you can either select the mg/kg/week unit directly in the calculator or manually divide the total weekly dose by 7 to get the daily dose before entering it.

What is the proper storage for Norditropin® pens?

Norditropin® pens should be refrigerated at 2°C to 8°C (36°F to 46°F) before first use. After the first injection, the pen can be stored for up to 21 or 28 days depending on the pen strength, either at room temperature (below 25°C/77°F) or in the refrigerator. Do not freeze and protect from light.

Is there a maximum dose the pen can deliver at one time?

Yes. The 5, 10, and 15 mg pens can deliver a maximum single dose of 4.0 mg. The 30 mg pen can deliver a maximum single dose of 8.0 mg. Doses larger than this must be split into multiple injections.

References

• 1. U.S. Food & Drug Administration. Drugs@FDA: Norditropin (somatropin) injection. View prescribing information.
• 2. Novo Nordisk. Norditropin® HCP Official Website. Visit site.
• 3. European Medicines Agency. Norditropin NordiFlex: Summary of Product Characteristics. View summary.
• 4. DailyMed - U.S. National Library of Medicine. NORDITROPIN FLEXPRO (somatropin) injection, solution. View drug label information.