DOSAGE CALCULATIONS MADE
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Difficulty: Easy
The healthcare provider orders cefazolin 500 mg IV every 8
hours. The pharmacy supplies a vial of cefazolin powder labeled
1 gram. The package insert states to reconstitute with 2.5 mL of
sterile water to yield a concentration of 330 mg/mL. How many
mL will the nurse administer?
A. 1.5 mL
B. 1.8 mL
C. 0.7 mL
D. 0.5 mL
Correct Answer: A. 1.5 mL
Rationale:
Step 1: Identify the desired dose and the available
concentration.
Step 2: Set up dimensional analysis to cancel units.
mL to administer=500 mg1×1 mL330 mg=500330=1.515 mLmL t
o administer=1500mg×330mg1mL=330500=1.515mL
Step 3: Round to the nearest tenth as appropriate for a 3 mL
syringe, resulting in 1.5 mL.
Medication Safety Note: Always verify the concentration on the
,vial. Note that "1 gram" is a dose, but the concentration after
reconstitution is in milligrams.
Question 2
Difficulty: Easy
A patient is prescribed 0.4 mg of digoxin orally. The medication
is available as an oral solution containing 0.05 mg/mL. How
many mL will the nurse administer?
A. 0.2 mL
B. 2 mL
C. 8 mL
D. 4 mL
Correct Answer: C. 8 mL
Rationale:
Step 1: Identify the dose ordered (0.4 mg) and the available
concentration (0.05 mg/mL).
Step 2: Set up the dimensional analysis equation.
mL to administer=0.4 mg1×1 mL0.05 mg=0.40.05=8 mLmL to ad
minister=10.4mg×0.05mg1mL=0.050.4=8mL
Step 3: The unit of mg cancels out, leaving mL. The answer is 8
mL.
Medication Safety Note: Digoxin has a narrow therapeutic
, range. Always double-check the dose and use a calibrated oral
syringe for precise measurement.
Question 3
Difficulty: Easy
The prescriber orders metoprolol 25 mg PO daily. The pharmacy
dispenses metoprolol 50 mg tablets. How many tablets will the
nurse administer?
A. 0.25 tablets
B. 2 tablets
C. 0.5 tablets
D. 1 tablet
Correct Answer: C. 0.5 tablets
Rationale:
Step 1: Identify the desired dose (25 mg) and the available dose
(50 mg).
Step 2: Set up dimensional analysis.
Tablets to administer=25 mg1×1 tablet50 mg=2550=0.5 tabletsT
ablets to administer=125mg×50mg1tablet=5025=0.5tablets
Step 3: The answer is half a tablet.
Medication Safety Note: A 25 mg dose of metoprolol is a
common starting dose. Ensure you are administering 0.5 of a 50
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Difficulty: Easy
The healthcare provider orders cefazolin 500 mg IV every 8
hours. The pharmacy supplies a vial of cefazolin powder labeled
1 gram. The package insert states to reconstitute with 2.5 mL of
sterile water to yield a concentration of 330 mg/mL. How many
mL will the nurse administer?
A. 1.5 mL
B. 1.8 mL
C. 0.7 mL
D. 0.5 mL
Correct Answer: A. 1.5 mL
Rationale:
Step 1: Identify the desired dose and the available
concentration.
Step 2: Set up dimensional analysis to cancel units.
mL to administer=500 mg1×1 mL330 mg=500330=1.515 mLmL t
o administer=1500mg×330mg1mL=330500=1.515mL
Step 3: Round to the nearest tenth as appropriate for a 3 mL
syringe, resulting in 1.5 mL.
Medication Safety Note: Always verify the concentration on the
,vial. Note that "1 gram" is a dose, but the concentration after
reconstitution is in milligrams.
Question 2
Difficulty: Easy
A patient is prescribed 0.4 mg of digoxin orally. The medication
is available as an oral solution containing 0.05 mg/mL. How
many mL will the nurse administer?
A. 0.2 mL
B. 2 mL
C. 8 mL
D. 4 mL
Correct Answer: C. 8 mL
Rationale:
Step 1: Identify the dose ordered (0.4 mg) and the available
concentration (0.05 mg/mL).
Step 2: Set up the dimensional analysis equation.
mL to administer=0.4 mg1×1 mL0.05 mg=0.40.05=8 mLmL to ad
minister=10.4mg×0.05mg1mL=0.050.4=8mL
Step 3: The unit of mg cancels out, leaving mL. The answer is 8
mL.
Medication Safety Note: Digoxin has a narrow therapeutic
, range. Always double-check the dose and use a calibrated oral
syringe for precise measurement.
Question 3
Difficulty: Easy
The prescriber orders metoprolol 25 mg PO daily. The pharmacy
dispenses metoprolol 50 mg tablets. How many tablets will the
nurse administer?
A. 0.25 tablets
B. 2 tablets
C. 0.5 tablets
D. 1 tablet
Correct Answer: C. 0.5 tablets
Rationale:
Step 1: Identify the desired dose (25 mg) and the available dose
(50 mg).
Step 2: Set up dimensional analysis.
Tablets to administer=25 mg1×1 tablet50 mg=2550=0.5 tabletsT
ablets to administer=125mg×50mg1tablet=5025=0.5tablets
Step 3: The answer is half a tablet.
Medication Safety Note: A 25 mg dose of metoprolol is a
common starting dose. Ensure you are administering 0.5 of a 50
