A nurse is preparing to administer phenytoin 200 mg PO to a client. Available is phenytoin oral suspension 125 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 the volume of phenytoin oral suspension needed to administer a dose of 200 mg, we need to use the concentration of the available suspension and perform a simple calculation. Here’s how to solve the problem:
1. Identify the concentration of the phenytoin oral suspension:
- The concentration is 125 mg/5 mL. This means that every 5 mL of the suspension contains 125 mg of phenytoin.
2. Set up a proportion to find the required volume (mL) to administer the desired dose (200 mg):
- We use the formula: Desired Dose (mg)×Volume Available (mL)Concentration (mg)\text{Desired Dose (mg)} \times \frac{\text{Volume Available (mL)}}{\text{Concentration (mg)}}Desired Dose (mg)×Concentration (mg)Volume Available (mL).
3. Substitute the values into the formula:
- Desired Dose = 200 mg
- Concentration = 125 mg in 5 mL
- We need to find the volume (mL) that will give us 200 mg.
The formula becomes:Volume to Administer=Desired Dose×Volume AvailableConcentration\text{Volume to Administer} = \frac{\text{Desired Dose} \times \text{Volume Available}}{\text{Concentration}}Volume to Administer=ConcentrationDesired Dose×Volume Available
Substituting the values:Volume to Administer=200 mg×5 mL125 mg\text{Volume to Administer} = \frac{200 \text{ mg} \times 5 \text{ mL}}{125 \text{ mg}}Volume to Administer=125 mg200 mg×5 mL Volume to Administer=1000 mL125\text{Volume to Administer} = \frac{1000 \text{ mL}}{125}Volume to Administer=1251000 mL Volume to Administer=8 mL\text{Volume to Administer} = 8 \text{ mL}Volume to Administer=8 mL
4. Round the answer to the nearest whole number:
- The calculation results in exactly 8 mL, so no rounding is needed.
Conclusion: The nurse should administer 8 mL of the phenytoin oral suspension to provide the 200 mg dose prescribed.
Explanation: The process involves using the given concentration to convert the desired dosage into the appropriate volume of medication. By setting up a proportion, we ensure that the amount of medication given corresponds accurately to the prescribed dose. This method is crucial in nursing practice to ensure that patients receive the correct amount of medication, which helps in maintaining therapeutic effectiveness and avoiding potential overdoses.