Question

a nurse is providing instruction to a client who has a new prescription for diphenhydramine 25 mg po every 6 hr. available is diphenhydramine syrup 12.5 mg/5 ml. how many tsp should the nurse instruct the client to take per dose? (round the answer to the nearest whole number. use a leading zero if it applies. do not use a trailing zero.)

Explanation:

Step1: Calculate mL per dose

We know the concentration is 12.5 mg/5 mL and the prescribed dose is 25 mg. Let $x$ be the volume in mL. Using proportion $\frac{12.5}{5}=\frac{25}{x}$. Cross - multiply: $12.5x = 25\times5$, so $x=\frac{25\times5}{12.5}=10$ mL.

Step2: Convert mL to tsp

Since 1 tsp = 5 mL, if the volume is $V = 10$ mL, then the number of tsp $n=\frac{V}{5}$. Substitute $V = 10$ mL into the formula, $n=\frac{10}{5}=2$.

Answer:

2