CALCULATIONS REVIEW PROBLEMS
1. Interpret the following codes taken from prescriptions:
a. Propranolol HCl 10 mg po tid ac & hs
c. Flurazepam 30 mg at HS prn sleep
10 mg of propranolol HCl by mouth three times a day before meals and at bedtime
Take 1 teaspoon (5 mL) every 6 hours for 10 days
30 mg of flurazepam at bedtime as needed for sleep
Take 1 capsule three times a day after meals
2. An injection for dental anesthesia contains 4% (w/v) of prilocaine hydrochloride and 1:200,000 (w/v) of epinephrine. Express the concentration of prilocaine as a ratio strength and the concentration of epinephrine as a percentage.
3. Norgestrel and ethinyl estradiol tablets are available containing 0.25 mg of norgestrel and 75 mcg of ethinyl estradiol. If a manufacturer wants to make 15,000 tablets, how many grams of each ingredient would be needed?
4. A prescription balance has a sensitivity requirement of 6 mg. Explain how you would weigh 20 mg of acetaminophen with an error not greater than 5%.
Weigh 120 mg of acetaminophen, dilute with 600 mg diluent to make 720 mg of mixture, and take 120 mg of mixture to contain 20 mg of acetaminophen needed.
5. A pharmacy technician attempts to weigh 350 mg of morphine sulfate on a balance of unknown accuracy. When the pharmacist checked the weight on a highly accurate balance, the actual weight is discovered to be 375 mg. Calculate the percentage error of the inaccurate balance.
6. An injection contains 60 mcg of drug A, 0.05 mg of drug B, and 8.18 mg of drug C in each milliliter. Calculate the milligrams percent (w/v) of drug A and the percentage (w/v) of drug B in the injection.
7. What is the volume, in milliliters, of 3 lb of mineral oil with a specific gravity of 0.85?
8. A vial contains 10 g of a powdered drug for reconstitution prior to use ...