Pharmacology Proctored ATI Practice Exam

How many mL of diphenhydramine elixir should be administered per dose if the prescription is 25 mg every 4 hours as needed, with an available concentration of 12.5 mg/5 mL?

1. 5 mL

2. 10 mL

3. 2.5 mL

4. 20 mL

The correct answer is: 10 mL

To calculate how many mL of diphenhydramine elixir should be administered per dose, you first need to determine how many mL contain 25 mg of diphenhydramine. Given that the concentration of diphenhydramine elixir is 12.5 mg per 5 mL, you can calculate the amount of diphenhydramine in 1 mL by dividing 12.5 mg by 5, which equals 2.5 mg per 1 mL. Since the prescription calls for 25 mg per dose, you would need to administer 25 mg ÷ 2.5 mg/mL = 10 mL per dose. Therefore, the correct answer is 10 mL. Option A (5 mL), option C (2.5 mL), and option D (20 mL) are incorrect based on the calculation provided.