Chapter 9. General dosage calculations (1 of 32) Sample Questions
1. A physician wants to switch a terminally-ill patient from slow-release Morphine sulphate tablets, 15 mg twice daily, to a liquid Morphine sulfate dosage form because the patient has difficulty in swallowing tablets. If a morphine sulfate solution containing 5 mg per mL is prescribed q4h, what volume should be dispensed for a 20-day supply to provide the same pain relief as the tablet regimen?
- A. 20 mL
- B. 60 mL
- C. 80 mL
- D. 100 mL
- E. 120 mL
Ans:
E
Working:
(5 mg)/(1 mL) x 6 times daily = 6 mL
6 mL x 20 days = 120 mL
Or
i.15 mg BID = 30 mg daily
ii.For 20 days: 30 mg x 20 = 600 mg are dispensed
Solution contains 5 mg/mL. 600 mg are contained in 600/5 = 120 mL
(5 mg)/(1 mL) x 6 times daily = 6 mL
6 mL x 20 days = 120 mL
Or
i.15 mg BID = 30 mg daily
ii.For 20 days: 30 mg x 20 = 600 mg are dispensed
Solution contains 5 mg/mL. 600 mg are contained in 600/5 = 120 mL