## INTRODUCTION

1. Interpret the following codes taken from prescriptions:

1. Propranolol HCl 10 mg po tid ac & hs

2. 1 tsp q6h × 10 days

3. Flurazepam 30 mg at hs prn sleep

4. Caps i tid pc

2. Solution:

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

2. Take 1 teaspoonful (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.

3. 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:

4. Norgestrel and ethinyl estradiol tablets are available containing 0.25 mg of norgestrel and 75 μg of ethinyl estradiol. If a manufacturer wants to make 15,000 tablets, how many grams of each ingredient would be needed?

Solution:

5. A prescription balance has a sensitivity requirement of 6 mg. Explain how you would weigh 20 mg of acetaminophen with an error not more 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.

6. 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:

7. An injection contains 60 μg 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:

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

Solution:

9. A vial contains 10 g of a powdered drug for reconstitution prior to use in an IV infusion. The label states that when 18.5 mL of diluent is added, the concentration of the resulting solution is 500 mg/mL. A medication order calls for a drug concentration of 300 mg/mL. How many milliliters of diluent should be added to the vial?

Solution:

10. How many grams of a 4% w/w hydrocortisone ointment must be mixed with a 0.5% w/w hydrocortisone ointment to achieve 30 g of an ointment with 2.5% strength?

Solution:

11. A pharmacist added 6 g of salicylic acid to 30 g of an ointment containing 4% salicylic acid, what would be the final concentration of the resulting mixture?

Solution:

12. If 500 mL of a 35% w/v solution is diluted to 1.75 L, what would be the resulting percentage strength?

Solution:

13. The phenytoin loading dose in children is 20 mg/kg infused at a rate of 0.5 mg/kg/min. Over how many minutes should the dose be administered to a 50-lb child?

Solution:

14. The following formula is for 60 sertraline hydrochloride capsules. Calculate the ...

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