NCLEX-RNPharmacological and Parenteral TherapiesMedium
A client is prescribed phenobarbital 60 mg PO TID for seizure control. The pharmacy dispenses phenobarbital oral solution labeled 20 mg/5 mL. How many milliliters should the nurse administer per dose?
- A20 mL
- B15 mL
- C5 mL
- D10 mL
Show answer & explanationAnswer & explanation
Correct answer: B. 15 mL
To calculate the volume to administer, use the formula: (Desired Dose / Available Dose) x Volume. (60 mg / 20 mg) x 5 mL = 3 x 5 mL = 15 mL. The nurse should administer 15 mL per dose.
Why the other options are wrong
- A. This would be the dose for 80 mg, not 60 mg.
- C. This would be the dose for 20 mg, not 60 mg.
- D. This would be the dose for 40 mg, not 60 mg.
Dosage Calculation (Oral Liquid)
Accurate dosage calculation for oral liquid medications is crucial for client safety. The formula (Desired Dose / Available Dose) x Volume allows nurses to determine the correct volume to administer based on the prescribed dose and the medication's concentration.
- Desired dose is the prescribed amount.
- Available dose is the concentration on the label.
- Volume is the amount of liquid containing the available dose.
- Formula: (Desired/Available) x Volume.
Memory trick: Desired on top, available on bottom, multiply by volume to get the right amount!