Prescription Interpretation: 14 vs 28 Capsules
A prescription for "one capsule by mouth two times a day for 14 administrations" means a total quantity of 14 capsules, not 28.
Understanding the Terminology
The key term here is "administrations" (or "doses"), which refers to the number of times the medication is given, not the number of individual capsules:
- 14 administrations = 14 separate dosing events
- Twice daily dosing = 2 administrations per day
- Duration: 14 administrations ÷ 2 administrations per day = 7 days of therapy
- Total capsules needed: 1 capsule × 14 administrations = 14 capsules
The Correct Calculation
If the prescription were intended to provide 14 days of twice-daily therapy, it would need to specify:
- "One capsule by mouth twice daily for 14 days" = 28 capsules total
- OR "One capsule by mouth twice daily for 28 administrations" = 28 capsules total
Clinical Context from Guidelines
The tuberculosis treatment guidelines 1 illustrate this principle clearly in their dosing tables. For example, when they specify "twice weekly for 36 doses," they mean exactly 36 individual administrations over 18 weeks, not 72 doses. Similarly, "seven days per week for 56 doses" means 56 total administrations over 8 weeks.
Common Pitfall to Avoid
This is a frequent source of prescribing and dispensing errors. When "administrations" or "doses" is specified as the duration metric rather than "days," the total quantity equals the number of administrations stated, with each administration consisting of the prescribed number of capsules per dose.