If a patient is prescribed Humulin N insulin 20 ml at a dose of 40 U daily, how many days will the supply last?

To determine how many days the supply of Humulin N insulin will last, we need to first understand the total amount of insulin in units that the patient has and how much they are using daily.

Humulin N expresses its concentration in units, where each milliliter (ml) of Humulin N typically contains 100 units of insulin. Therefore, if the patient has a total of 20 ml of Humulin N, we can calculate the total units of insulin:

Total units = 20 ml x 100 units/ml = 2000 units.

The patient is prescribed a daily dose of 40 units. To find out how many days the supply will last, we divide the total amount of insulin by the daily dose:

Days supply lasts = Total units / Daily dose = 2000 units / 40 units/day = 50 days.

This calculation confirms that the correct answer reflects the duration the insulin supply will last, which indeed is 50 days. Understanding how to convert milliliters of insulin into total units and calculating the length of supply based on the prescribed dosage is essential for pharmacy practice.