Overview
This lecture explains how to calculate the quantity of medication a pharmacist should dispense, based on dose, frequency, and duration of a prescription.
Quantity to Dispense: Formula and Steps
- To calculate quantity to dispense: use the formula Dose x Frequency x Duration.
- Required information: amount per dose, number of doses per day (frequency), and total number of treatment days (duration).
Example 1: Simple Calculation
- Prescription: 1 tablet twice daily for 10 days.
- Tablets per day = 2 doses/day x 1 tablet/dose = 2 tablets/day.
- Total tablets = 2 tablets/day x 10 days = 20 tablets to dispense.
Example 2: Dose Conversion
- Prescription: 500 mg per dose, 3 times daily for 14 days, 250 mg tablets available.
- Tablets per dose = 500 mg / 250 mg per tablet = 2 tablets/dose.
- Tablets per day = 3 doses/day x 2 tablets/dose = 6 tablets/day.
- Total tablets = 6 tablets/day x 14 days = 84 tablets to dispense.
Practice Problem & Solution
- Prescription: 250 mg per dose, twice daily for 7 days, 125 mg tablets.
- Tablets per dose = 250 mg / 125 mg = 2 tablets/dose.
- Tablets per day = 2 doses/day x 2 tablets/dose = 4 tablets/day.
- Total tablets = 4 tablets/day x 7 days = 28 tablets to dispense.
Key Terms & Definitions
- Dose — The amount of medication taken at one time.
- Frequency — How many times per day the medication is taken.
- Duration — The total number of days the medication is to be taken.
- Quantity to dispense — The total number of tablets or units the pharmacist provides for the full course.
Action Items / Next Steps
- Practice with additional problems using the quantity to dispense formula.
- Watch the next video on calculating the quantity of an ingredient.