An adult client receives a prescription for diphenhydramine 15 mL by mouth every 12 hours PRN for pruritus. The bottle is labeled, “diphenhydramine 12.5 mg/5 mL.” What is the total daily dose in mg that the client receives? (Enter numerical value only.)
The correct answer and Explanation is :
To determine the total daily dose of diphenhydramine the client receives, follow these steps:
- Calculate the Dose Per Administration:
- The prescription is for 15 mL of diphenhydramine every 12 hours.
- The concentration of diphenhydramine is 12.5 mg/5 mL.
- To find out how many milligrams are in 15 mL, use the proportion based on the concentration:
[
\text{Amount of diphenhydramine in 15 mL} = \left(\frac{12.5 \text{ mg}}{5 \text{ mL}}\right) \times 15 \text{ mL} = 37.5 \text{ mg}
] - Therefore, each dose of 15 mL contains 37.5 mg of diphenhydramine.
- Determine the Number of Doses Per Day:
- The client takes diphenhydramine every 12 hours, which means there are 2 doses in a 24-hour period.
- Calculate the Total Daily Dose:
- Multiply the amount per dose by the number of doses per day:
[
\text{Total daily dose} = 37.5 \text{ mg/dose} \times 2 \text{ doses/day} = 75 \text{ mg/day}
]
So, the total daily dose of diphenhydramine that the client receives is 75 mg.
Explanation:
The calculation is based on the provided concentration of diphenhydramine in the liquid form, and the frequency of administration. By knowing that the concentration is 12.5 mg per 5 mL, you can first determine how much of the medication is delivered in a 15 mL dose.
Next, considering that the medication is given every 12 hours, you calculate the total daily dose by multiplying the single dose amount by the number of doses in a day (2). This results in the total daily intake of 75 mg of diphenhydramine, ensuring the proper dosage is administered to manage pruritus effectively while adhering to the prescription guidelines.