An adult client is prescribed cefazolin 0.75\text{ g} intramuscularly for surgical prophyl… — NCLEX-PN

An adult client is prescribed cefazolin $0.75\text{ g}$ intramuscularly for surgical prophylaxis. The medication is supplied as a $1\text{ g}$ vial of dry powder. The manufacturer's instructions state to reconstitute the powder by adding $2.0\text{ mL}$ of sterile water for injection, yielding a total volume of $2.5\text{ mL}$ with a final concentration of $400\text{ mg/mL}$ . How many $\text{mL}$ should be administered to the client? (Record the answer to the nearest tenth. Do not include units in your answer.)

Answer: 1.9 mL

Answer

1.9

To determine the correct volume, the prescribed dose must first be converted to match the available unit:

0.75\text{ g} = 750\text{ mg}

. When a final concentration is provided (

400\text{ mg/mL}

), the diluent amount and total volume become extraneous information. Using the standard formula, divide the desired dose (

750\text{ mg}

) by the available concentration (

400\text{ mg}

) and multiply by the base volume (

1\text{ mL}

), which equals

1.875\text{ mL}

. Rounding to the nearest tenth yields

1.9\text{ mL}

Step-by-Step Solution

Convert the prescribed dose from grams to milligrams.

0.75\text{ g} \times 1000\text{ mg/g} = 750\text{ mg}

The available concentration is provided in milligrams, so the prescribed dose must be in the same unit of measurement.

Identify the final medication concentration from the provided instructions.

The final concentration is

400\text{ mg/mL}

Extraneous information such as the diluent volume (

2.0\text{ mL}

) and total reconstituted volume (

2.5\text{ mL}

) should be ignored when the final concentration is explicitly provided.

Calculate the volume to administer.

\frac{750\text{ mg}}{400\text{ mg}} \times 1\text{ mL} = 1.875\text{ mL}

This formula determines the exact liquid volume containing the required dose.

Round the final answer to the nearest tenth.

1.875\text{ mL}

rounds to

1.9\text{ mL}

Standard rounding rules state that if the hundredths digit is 5 or greater, the tenths digit is rounded up.

Key Concept

Medication Reconstitution and Dosage Calculation

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