CHEM120

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

Medication Calculation Examination Study Guide

• Sample: Dr. B. orders a liter of D5W to run this 8-hour shift. The drop factor is 15. What

is the drip rate per minute? Solution: 1 liter = 1000 cc of solution, next convert 8 hours to minutes (8 X 60 minutes) = 480 minutes 1000 cc x 15 gtts ÷ 480 minutes = 31.25 or 31 gtts/min Answer: 31 gtts/min

• Your patient weighs 200 lb and the order is to infuse 250 mg dobutamine in 500 ml NS at 10 mcg/kg/min. How many milligrams of dobutamine will infuse per hour?

200÷2.2= 90.90kg: 60 minutes = 1 hour: 10 mcg x 90.90kg x 60 min=5454.54 mcg/hour ÷ 1000 = 54.54mg/hr or 54.5mg/hr

Answer:_____54.5mg/hr_____

The “7 Rights” of Medication Administration

Right Patient Right Drug Right Dose Right Route Right Time Right Documentation Right to Refuse

Conversion Table

• 1 kilogram (kg) = 1000 grams (g) • 1 gram (g) = 1000 milligrams (mg)

– Convert Grams to Milligrams by Multiplying grams by 1,000 – Convert Milligrams to grams by dividing milligrams by 1,000

• 1 milligram (mg) = 1000 micrograms (mcg) • Grains (gr.) 15 = 1 Gram (g) or 1000 milligrams (mg)

– To convert g. to gr multiply by 15 – To convert gr to g divide by 15.

• 1 Grain (gr.) = 60 Milligrams (mg) – To convert gr. to mg multiply gr. by 60 – To convert mg to gr. divide mg. by 60

• 1ml = 1 cc • 1 ounce = 30 ml • 1 tablespoon (T or tbsp) = 15 ml • 1 teaspoon (t or tsp) = 5 ml • 2.2 lb = 1 kg • To convert pounds to kg divide pounds by 2.2 • To convert kg to pounds multiply by 2.2

Medication Calculation Examination Study Guide (Revised 06/10) Page 2 of 2