NCLEX: Drug Dosage Calculation Exam 1

1. A patient is receiving 160 mg of methylprednisolone IM every 12 hours. You have on hand two vials that each contains 125 mg/2 mL. How much will you draw into a syringe?
2. You have available lorazepam (Ativan) 0.5 mg tablets, and you need to administer 1 mg PO. How many tablets will you administer?
3. A patient is instructed to take acetaminophen (Tylenol) liquid (elixir) 650 mg qid. The elixir is 160 mg/5 mL. How many milliliter per dose should the patient take?
4. The physician writes a “now” order for codeine 45 mg IM for a patient with a vertebral compression fracture. You have on hand codeine 60 mg/2 mL. How many milliliters should you give?
5. A patient with heart failure has a daily order for digoxin 0.25 mg PO. Digoxin 0.125 mg tablets are available. How many tablets should you give?
6. A patient on hemodialysis must maintain careful intake and output. For breakfast he had 1 measured cup of coffee and 3 oz of milk on his cereal. For lunch he drank 6 oz of lemonade and ate 1 cup of soup. For supper he drank 1 measured cup of coffee. He took his morning and evening pills with 4 oz of water each time. Has he stayed within his 1000 mL fluid restriction?
7. You have on hand hydromorphone (Dilaudid) 4 mg/mL. You need to administer 0.015 mg/kg to a patient who weighs 150 pounds. How many milliliters should you administer?
8. You have an order to administer 40 mg of methadone SC for opioid detoxification. You have on hand 30 mg/mL. How much should you draw into the syringe?
9. A patient is placed on methadone maintenance therapy of 15 mg/day PO. It is supplied as 10 mg in 5 mL oral solution. How many milliliters should you instruct the patient to take?
10. A homebound patient must take 400,000 units of nystatin PO every 4 hours, to swish in the mouth and then swallow. It is available as 100,000 units/5 mL. The patient has only household measuring spoons. How should the patient be instructed to take the dose?

Answers

1. (160 mg x 2 mL) / 125 mg = 2.6 mL
2. (1 mg x 1 tablet) / 0.5 mg = 2 tablets
3. (650 mg x 5 mL) / 160 mg = 20 mL
4. (45 mg x 2 mL) /  60 mg=  1.5 mL
5. (0.25 mg x 1 tablet) / 0.125 mg= 2 tablets
6. Convert first to mL :
   • (1 cup x 240 mL) / 1 cup = 240 mL ,
   • (3 oz x 30 mL) / 1 oz = 90 mL,
   • (6 oz x 30 mL)/ 1 oz = 180 mL,
   • (4 oz x 30 mL)/  1 oz = 120 mL
   • 240 + 90 + 180 + 240 + 240 + 120 + 120 = 1230 mL
     No, he has exceeded his fluid restriction limit by 230 mL.
7. (0.015 mg x 1 kg x 150 pounds x 1 mL) / ( 1 kg x 2.2 pounds x 4 mg) = 0.26 mL
8. (40 mg x 1 mL) / 30 mL =1.3 mL
9. (15 mg x 5 mL) / 10 mg = 7.5 mL
10. (400,000 units x 5 mL x 1 teaspoon) / (100,000 units x 5 mL)= 4 teaspoons