Prescription Calculation for 90-Day Treatment
For a 90-day treatment requiring two tablets per month, prescribe 6 tablets total (2 tablets/month × 3 months = 6 tablets).
Calculation Breakdown
The arithmetic is straightforward:
- Monthly requirement: 2 tablets
- Treatment duration: 90 days = 3 months
- Total tablets needed: 2 × 3 = 6 tablets
Practical Prescribing Considerations
When writing this prescription:
- Dispense: 6 tablets
- Directions: Take 2 tablets once monthly (or specify the exact schedule if tablets are to be taken on specific days)
- Refills: None (if this is a one-time 90-day course)
Important Caveats
Verify the dosing schedule: The "2 tablets per month" instruction is unusual for most medications. Confirm whether this means:
- 2 tablets taken together once per month
- 1 tablet taken twice during the month
- Some other specific schedule
Account for potential interruptions: While the mathematical calculation yields 6 tablets for exactly 90 days, consider whether the patient might need a small buffer supply if doses could be missed or delayed. However, for controlled substances or medications with safety concerns, prescribe only the exact amount needed 1.
Document clearly: Specify on the prescription the exact dates or intervals when tablets should be taken to avoid patient confusion, as infrequent dosing schedules (monthly) are prone to medication errors 1.