## CALCULATIONS REVIEW PROBLEMS

1. Interpret the following codes taken from prescriptions:

a. Propranolol HCl 10 mg po tid ac & hs

b. 1 tsp q6h x 10d

c. Flurazepam 30 mg at HS prn sleep

d. Caps i tid pc

Solution:

1. 10 mg of propranolol HCl by mouth three times a day before meals and at bedtime

2. Take 1 teaspoon (5 mL) every 6 hours for 10 days

3. 30 mg of flurazepam at bedtime as needed for sleep

4. 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.

Solution:

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?

Solution:

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%.

Solution:

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.

Solution:

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.

Solution:

7. What is the volume, in milliliters, of 3 lb of mineral oil with a specific gravity of 0.85?

Solution:

8. A vial contains 10 g of a powdered drug for reconstitution prior to use in ...

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