TEST BANK BASED ON:
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
1.
Chapter Reference: Chapter 1 — Section 1.1: Units & Basic
Conversions (Safety)
Stem: A provider writes an order for 0.5 mg of naloxone. You
must document the dose in micrograms (mcg). What is the
correct equivalent?
A. 50 mcg
B. 500 mcg
C. 5,000 mcg
D. 50,000 mcg
Correct Answer: B
Rationales:
, • Correct (B): 0.5 mg → convert mg to mcg: 1 mg = 1000
mcg. Calculation: 0.5 mg × 1000 mcg/mg = 500 mcg.
• A (50 mcg): This reflects moving the decimal left one place
(0.5 → 0.05) before conversion: incorrect decimal
placement.
• C (5,000 mcg): This would be 5 mg, not 0.5 mg — an extra
factor of 10 error.
• D (50,000 mcg): This equals 50 mg — two orders of
magnitude too large.
Teaching Point: Always convert units stepwise: mg → mcg
multiply by 1,000.
2.
Chapter Reference: Chapter 1 — Section 1.1: Tablet Fractioning
& Safe Dosing
Stem: An order reads: digoxin 0.125 mg PO daily. The available
tablet is 0.25 mg. How many tablets should you give?
A. 0.25 tablet
B. 0.5 tablet
C. 1 tablet
D. 2 tablets
Correct Answer: B
Rationales:
, • Correct (B): Required dose 0.125 mg. Available = 0.25
mg/tablet. Calculation: 0.125 mg ÷ 0.25 mg/tablet = 0.5
tablet.
• A (0.25 tablet): This would provide 0.0625 mg (0.25 × 0.25
mg); decimal error halving incorrectly.
• C (1 tablet): Would give 0.25 mg — double the ordered
dose.
• D (2 tablets): Would give 0.5 mg — four times the ordered
dose.
Teaching Point: When tablet strengths differ, use D/H × Q to
calculate fractional tablets.
3.
Chapter Reference: Chapter 1 — Section 1.2: IV Infusion
Volume & Time Calculations
Stem: Cefazolin 1 g is ordered IV to infuse in 30 minutes.
Pharmacy supplies cefazolin reconstituted in 250 mL. What
infusion rate (mL/hr) should you program?
A. 250 mL/hr
B. 500 mL/hr
C. 750 mL/hr
D. 1000 mL/hr
Correct Answer: B
Rationales:
, • Correct (B): Total volume 250 mL over 30 minutes (0.5
hour). Calculation: 250 mL ÷ 0.5 hr = 500 mL/hr.
• A (250 mL/hr): Would infuse over 1 hour; too slow (half
the ordered rate).
• C (750 mL/hr): Wrong division—appears to add 50% extra
flow.
• D (1000 mL/hr): Would infuse over 15 minutes — four
times too fast.
Teaching Point: Convert minutes to hours before calculating
mL/hr (minutes ÷ 60 = hours).
4.
Chapter Reference: Chapter 1 — Section 1.3: Drip Rate
Calculations (gtt/min)
Stem: You must infuse 500 mL of D5W over 4 hours using a
microdrip set (60 gtt/mL). What is the correct flow in
drops/min?
A. 83 gtt/min
B. 100 gtt/min
C. 125 gtt/min
D. 150 gtt/min
Correct Answer: C
Rationales:
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
1.
Chapter Reference: Chapter 1 — Section 1.1: Units & Basic
Conversions (Safety)
Stem: A provider writes an order for 0.5 mg of naloxone. You
must document the dose in micrograms (mcg). What is the
correct equivalent?
A. 50 mcg
B. 500 mcg
C. 5,000 mcg
D. 50,000 mcg
Correct Answer: B
Rationales:
, • Correct (B): 0.5 mg → convert mg to mcg: 1 mg = 1000
mcg. Calculation: 0.5 mg × 1000 mcg/mg = 500 mcg.
• A (50 mcg): This reflects moving the decimal left one place
(0.5 → 0.05) before conversion: incorrect decimal
placement.
• C (5,000 mcg): This would be 5 mg, not 0.5 mg — an extra
factor of 10 error.
• D (50,000 mcg): This equals 50 mg — two orders of
magnitude too large.
Teaching Point: Always convert units stepwise: mg → mcg
multiply by 1,000.
2.
Chapter Reference: Chapter 1 — Section 1.1: Tablet Fractioning
& Safe Dosing
Stem: An order reads: digoxin 0.125 mg PO daily. The available
tablet is 0.25 mg. How many tablets should you give?
A. 0.25 tablet
B. 0.5 tablet
C. 1 tablet
D. 2 tablets
Correct Answer: B
Rationales:
, • Correct (B): Required dose 0.125 mg. Available = 0.25
mg/tablet. Calculation: 0.125 mg ÷ 0.25 mg/tablet = 0.5
tablet.
• A (0.25 tablet): This would provide 0.0625 mg (0.25 × 0.25
mg); decimal error halving incorrectly.
• C (1 tablet): Would give 0.25 mg — double the ordered
dose.
• D (2 tablets): Would give 0.5 mg — four times the ordered
dose.
Teaching Point: When tablet strengths differ, use D/H × Q to
calculate fractional tablets.
3.
Chapter Reference: Chapter 1 — Section 1.2: IV Infusion
Volume & Time Calculations
Stem: Cefazolin 1 g is ordered IV to infuse in 30 minutes.
Pharmacy supplies cefazolin reconstituted in 250 mL. What
infusion rate (mL/hr) should you program?
A. 250 mL/hr
B. 500 mL/hr
C. 750 mL/hr
D. 1000 mL/hr
Correct Answer: B
Rationales:
, • Correct (B): Total volume 250 mL over 30 minutes (0.5
hour). Calculation: 250 mL ÷ 0.5 hr = 500 mL/hr.
• A (250 mL/hr): Would infuse over 1 hour; too slow (half
the ordered rate).
• C (750 mL/hr): Wrong division—appears to add 50% extra
flow.
• D (1000 mL/hr): Would infuse over 15 minutes — four
times too fast.
Teaching Point: Convert minutes to hours before calculating
mL/hr (minutes ÷ 60 = hours).
4.
Chapter Reference: Chapter 1 — Section 1.3: Drip Rate
Calculations (gtt/min)
Stem: You must infuse 500 mL of D5W over 4 hours using a
microdrip set (60 gtt/mL). What is the correct flow in
drops/min?
A. 83 gtt/min
B. 100 gtt/min
C. 125 gtt/min
D. 150 gtt/min
Correct Answer: C
Rationales:
