A pharmacy technician receives a prescription for a 10 mL vial of insulin that contains 100 units/mL with instructions for the patient to take 20 units in the morning and 20 in the evening. What is the days' supply for this prescription?

To determine the days' supply for the prescription, it is essential to calculate the total number of units required by the patient each day and then relate that to the total amount of insulin provided in the vial.

The prescription indicates that the insulin vial contains 100 units/mL, and since the vial has a total volume of 10 mL, the total number of units of insulin in the vial can be calculated as follows:

Total Units = Concentration (units/mL) × Volume (mL) = 100 units/mL × 10 mL = 1000 units.

Next, the instructions specify that the patient is to take 20 units in the morning and 20 units in the evening. This results in a total daily requirement of:

Daily Requirement = Morning Dose + Evening Dose = 20 units + 20 units = 40 units.

To find the number of days the prescription will last, we divide the total units in the vial by the daily requirement:

Days' Supply = Total Units / Daily Requirement = 1000 units / 40 units/day = 25 days.

Thus, the days' supply for this prescription is 25 days.