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Days Supply Formula:
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Days supply calculation is a fundamental pharmacy practice that determines how long a medication will last based on the total quantity dispensed and the prescribed daily dosage. This helps ensure patients have adequate medication until their next refill or appointment.
The calculator uses the simple formula:
Where:
Explanation: This calculation divides the total quantity of medication by the daily dosage to determine how many days the supply will last.
Details: Accurate days supply calculation is essential for medication adherence, insurance billing, refill management, and preventing medication shortages. It helps pharmacists ensure patients have continuous access to their medications.
Tips: Enter the total quantity of medication in units and the prescribed daily dosage in units per day. Both values must be positive numbers.
Q1: What if the medication is taken multiple times per day?
A: The daily dose should be the total units taken per day. For example, if a patient takes 2 tablets twice daily, the daily dose would be 4 tablets.
Q2: How do I calculate for PRN (as needed) medications?
A: For PRN medications, use the maximum allowed daily dose or the average expected daily usage based on the prescription instructions.
Q3: What about medications with variable dosing?
A: For titratable medications, use the expected average daily dose or calculate based on the prescribed dosing schedule.
Q4: How should combination medications be handled?
A: For fixed-dose combination products, calculate based on the number of units (tablets, capsules, etc.) rather than individual active ingredients.
Q5: Are there special considerations for insulin?
A: Insulin days supply is typically calculated based on total units and the patient's average daily insulin requirement, considering both basal and bolus doses.