Medication Calculation Examination
Study Guide
D = Desired Dose
Q = Quantity of Solution
H = Strength on Hand
X = Unknown quantity of Drug
• Sample: Physician orders 500 mg of ibuprofen (desired Dose) for a patient and you have
250 mg (Quantity on Hand) tablets (Quantity of solution) on hand.
Solution: D ÷ H x Q = X 500mg ÷ 250 mg x 1 tablet = 2 tablets
Answer: 2 tablets.
• Sample: Physician orders 1500 mg of liquid ibuprofen for a patient. Quantity of
Ibuprofen is 500 mg in 1 cc, how much will you administer?
Solution: 1500 mg ÷ 500 mg x 1cc = 3 cc
Answer: 3 cc
Dosage and Conversions
Sample: MD orders 300 mg of Ibuprophen to be taken by a 6 kg infant every 4 hours. Label
shows 75 – 150 mg/kg per day. Is the physician’s order within normal range?
Solution: 6 x 75 = 450 mg (minimum dosage per day); 150 X6 = 900 (maximum dosage per
day)
24 ÷ 4 = 6 dosages : 300 x 6 = 1800
Answer: Dosage is not within range
IV Calculations
• [amount of fluid to be infused] x [drop factor] ÷ minutes to infuse = gtts/min
• Sample: Dr. A. orders your patient to receive 125 ml of D5W an hour for the next 8
hours. The nursing unit uses tubing with a drop factor of 10. What is the drip rate per
minute?
• Solution: Convert 1 hour to 60 minutes: 1250 x 10 gtts ÷ 60 minutes = 20.83 or 21
gtts/min
Answer: 21 gtts/min
Medication Calculation Examination Study Guide (Revised 06/10) Page 1 of 2
