A practical nurse is caring for a pediatric client who weighs 60\text{ lb } 8\text{ oz}. T… — NCLEX-PN

A practical nurse is caring for a pediatric client who weighs $60\text{ lb } 8\text{ oz}$ . The health care provider originally prescribed valproic acid $18\text{ mg/kg/day}$ PO divided into equal doses administered every 8 hours. Due to a recent subtherapeutic serum trough level, the provider wrote a new prescription to increase the client's total daily dose by $25\%$ . The pharmacy dispenses valproic acid oral syrup at a concentration of $250\text{ mg}/5\text{ mL}$ .

How many mL should the practical nurse administer for ONE dose? (Record answer to the nearest tenth. Do not include units in answer.)

Answer: 4.1 mL

Answer

4.1

The correct calculation requires converting the client's weight from pounds and ounces to kilograms, determining the base daily dose, applying a 25% increase, dividing that amount by 3 to account for the every 8-hour schedule, and finally using the pharmacy's supplied concentration to find the liquid volume per dose.

Step-by-Step Solution

Convert the client's weight from pounds and ounces to kilograms.

27.5\text{ kg}

Since 16 ounces equal 1 pound, 8 ounces is 0.5 pounds, making the total weight 60.5 pounds. Dividing by 2.2 lb/kg yields the weight in kilograms (

60.5 \div 2.2 = 27.5

Calculate the baseline total daily dose of valproic acid.

495\text{ mg/day}

Multiply the client's weight in kilograms by the prescribed base rate of

18\text{ mg/kg/day}

(

27.5 \times 18 = 495

Calculate the newly prescribed increased total daily dose.

618.75\text{ mg/day}

The provider increased the dose by

25\%

. Multiply the baseline daily dose by 1.25 (or add

25\%

of 495) to find the new required daily amount (

495 \times 1.25 = 618.75

Determine the amount of medication required for a single dose.

206.25\text{ mg/dose}

The medication is scheduled to be administered every 8 hours, which equals 3 doses per 24-hour period (

24 \div 8 = 3

). Divide the new total daily dose by 3 (

618.75 \div 3 = 206.25

Calculate the volume of oral syrup to administer for one dose.

4.125\text{ mL}

Use the desired over have formula: (Desired / Have) * Volume. The desired dose is

206.25\text{ mg}

, and the supplied concentration is

250\text{ mg}

per

5\text{ mL}

(

(206.25 \div 250) \times 5 = 4.125

Round the final volume to the nearest tenth as instructed.

4.1\text{ mL}

The hundredths place is 2 (which is less than 5), so the tenths place remains unchanged.

Key Concept

Complex pediatric weight-based dosage calculation including percentage adjustments and fractionated daily dosing.

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