NCLEX: Drug Dosage Calculation Exam 6

1. Your order reads ceftizoxime 1 g IV piggyback (IVPB) every 8 hours. The pharmacy supplies it in 100 mL D5W. You need to infuse it over 30 minutes. Using gravity drip tubing with a drop factor of 10, how fast will you run the piggyback?

1. 23 gtts/min
2. 33 gtts/min
3. 38 gtts/min
4. 42 gtts/min

2. You need to infuse 1000 mL of normal saline IV over 6 hours. How many milliliters per hour do you set on the IV infusion controller?

1. 100 mL/hour
2. 167 mL/hour
3. 150 mL/hour
4. 3 mL/hour

3. You have an order for fosphenytoin (Cerebyx) 100 phenytoin equivalents (PE) IVPB qid. It arrives in 50 mL of normal saline, with a note on the piggyback bag not to infuse faster than 150 PE/minute. How many milliliters per hour should you set on the controller?

1. 4,500 mL/hour maximum rate
2. 4,800 mL/hour maximum rate
3. 5,000 mL/hour maximum rate
4. 5,250 mL/hour maximum rate

4. You have 500 mL of lipids on a second IV infusion controller to piggyback into a primary hyperalimentation line. You want to run the infusion over 24 hours. At what rate should you run the lipids?

1. 35 mL/hour
2. 33 mL/hour
3. 24 mL/hour
4. 21 mL/hour

5. You have an order for 500 mg vancomycin IVPB every 6 hours for a patient who weighs 120 lbs. You know that you can safely administer up to 40 mg/kg/day. Is the order safe?

1. patient is receiving 36.7 mg/kg/day
2. patient is receiving 9.2 mg/kg/day
3. patient is receiving 40.0 mg/kg/day
4. patient is receiving 18.4 mg/kg/day

6. You have 350 mL packed red blood cells that you want to infuse IV over 2 hours. There is no controller available. Your blood tubing delivers 10 gtts/mL. How many drops per minute should you set?

1. 3 gtts/minute
2. 18 gtts/minute
3. 29 gtts/minute
4. 33 gtts/minute

7. You need to infuse corticotropin (Acthar) 25 U in 500 mL D5W IV over 8 hours. How many milliliters per hour do you infuse on a controller?

1. 25 mL/hour
2. 38 mL/hour
3. 55 mL/hour
4. 63 mL/hour

8. A patient is taking acetaminophen (Tylenol) 325 mg, 2 tablets PO every 6 hours. How many grams is the patient receiving in 24 hours?

1. 2.6 g
2. 2 g
3. 1.6 g
4. 1 g

9. You have an order for diphenhydramine hydrochloride (Benadryl) 40 mg IM now. You have on hand Benadryl 25 mg/mL. How many milliliters do you prepare?

1. 2.5 mL
2. 2 mL
3. 1 mL
4. 1.6 mL

10. You have digoxin (Lanoxin) 0.25 mg tablets, and you need to administer 0.375 mg PO. How many tablets should you administer?

1. 0.7 tablet
2. 1 tablet
3. 1.5 tablets
4. 2 tablets

Answers and Rationales

1. Answer: B. (100mL/30 mins) x (10 gtts/mL)= 33 gtts/min
2. Answer: B. (1000 mL/6 hrs)= 167 mL/hour
3. Answer: A. (150 PE/minute) x (50 mL/100 PE) x (60 minutes/1 hr)= 4,500 mL/hour maximum rate *Although 4500 mL/hour is the maximum rate, there is no reason to run it that fast; doing so could damage the vein. Most piggybacks are infused over 20 to 30 minutes, or according to hospital policy. 50 mL infused over 30 minutes would be set at 100 mL/hour, which is well under the maximum rate.
4. Answer: D. 21 mL/hour. (500 mL/ 24 hrs)= 21 mL/hour
5. Answer: A. (500 mg/120 lbs) x (4 doses/ day) x (2.2 lbs/1 kg)= patient is receiving 36.7 mg/kg/day *36.7 mg/kg is less than the safe dose of 40 mg/kg, so it is safe.
6. Answer: C. (350 mL/ 2 hrs) x (1 hr/60 mins) x (10 gtts/1 mL)= 29 gtts/minute
7. Answer: D. (500 mL/8 hrs)= 63 mL/hour
8. Answer: A. (325 mg/tablet) x (2 tablets/dose) x (4 doses/day) x (1g /1,000 mg)= 2.6 g
9. Answer: D. 40 mg x (1 mL/25 mg)= 1.6 mL
10. Answer: C. 0.375 mg x (1 tablet/0.25 mg)= 1.5 tablets