A nurse is preparing to administer phenytoin 75 mg PO.

A nurse is preparing to administer phenytoin 75 mg PO. Available is phenytoin suspension 25 mg/5 mL. How many mL should the nurse administer? (Round the answer to the nearest whole number.

Use a leading zero if it applies.

Do not use a trailing zero.

The Correct Answer and Explanation is:

To determine how many milliliters (mL) of phenytoin suspension the nurse should administer, follow these steps:

1. Identify the required dosage and the concentration of the suspension:
   • Required dosage: 75 mg
   • Concentration of the phenytoin suspension: 25 mg/5 mL
2. Set up the proportion to find out how many mL of suspension are needed to get 75 mg of phenytoin.The concentration of the phenytoin suspension is 25 mg in 5 mL. To find the volume (V) needed for a 75 mg dose, set up the following proportion:25 mg5 mL=75 mgV mL\frac{25 \text{ mg}}{5 \text{ mL}} = \frac{75 \text{ mg}}{V \text{ mL}}5 mL25 mg​=V mL75 mg​
3. Solve for V:25 mg5 mL=75 mgV mL\frac{25 \text{ mg}}{5 \text{ mL}} = \frac{75 \text{ mg}}{V \text{ mL}}5 mL25 mg​=V mL75 mg​Cross-multiply to solve for V:25 mg×V mL=75 mg×5 mL25 \text{ mg} \times V \text{ mL} = 75 \text{ mg} \times 5 \text{ mL}25 mg×V mL=75 mg×5 mL 25V=37525V = 37525V=375 V=37525V = \frac{375}{25}V=25375​ V=15 mLV = 15 \text{ mL}V=15 mL
4. Round the answer to the nearest whole number:In this case, 15 mL is already a whole number, so no rounding is needed.

Explanation:

Phenytoin is provided in a suspension with a concentration of 25 mg per 5 mL. The desired dosage is 75 mg. To determine the volume required, you use a proportion based on the concentration of the suspension. By setting up a proportion where 25 mg is to 5 mL as 75 mg is to V mL, and solving for V, you determine that 15 mL of the suspension is needed to deliver 75 mg of phenytoin.

This calculation ensures accurate medication administration, which is crucial for effective patient care and avoiding medication errors. The step-by-step approach to setting up and solving the proportion helps in understanding and performing accurate dosage calculations in clinical settings.