A provider prescribes cefazolin 300\text{ mg} deep intramuscularly for a client treating a… — NCLEX-PN

A provider prescribes cefazolin $300\text{ mg}$ deep intramuscularly for a client treating a cellulitis infection. The supply on hand is a $500\text{ mg}$ vial of powdered cefazolin. The label instructions read: 'Reconstitute by adding $2.0\text{ mL}$ of sterile water for injection. The resulting reconstituted solution contains $225\text{ mg/mL}$ of cefazolin.' Determine the volume in milliliters required for a single dose. (Record answer to the nearest tenth. Do not include units in answer.)

Answer: 1.3 mL

Answer

1.3

The correct volume is determined by using the final reconstituted concentration of

225\text{ mg/mL}

. By applying the formula (Desired Dose / Available Concentration) × Volume, the calculation is

(300\text{ mg} / 225\text{ mg}) \times 1\text{ mL} = 1.333...\text{ mL}

. Rounding to the nearest tenth yields

1.3\text{ mL}

. The values

500\text{ mg}

and

2.0\text{ mL}

are distractors.

Step-by-Step Solution

Identify the desired dose and the available medication concentration from the problem statement.

Desired dose =

300\text{ mg}

; Available concentration =

225\text{ mg/mL}

Correctly isolating the final yield concentration is critical, as the diluent volume (

2.0\text{ mL}

) and total powder mass (

500\text{ mg}

) are extraneous information meant to test the nurse's ability to extract relevant clinical data.

Apply standard dosage calculation principles to determine the volume.

\frac{300\text{ mg}}{225\text{ mg}} \times 1\text{ mL} = 1.333...\text{ mL}

Dividing the prescribed dose by the concentration on hand provides the exact volume of liquid needed to deliver the correct mass of the drug.

Round the calculated volume to the nearest tenth.

1.3

Rounding rules for standard medication administration dictate that volumes greater than

1\text{ mL}

should be rounded to the nearest tenth to ensure accurate measurement in a standard syringe.

Key Concept

Reconstituted Medication Dosage Calculation

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