30
Pharmacy Practice
Review Calculations
1. The recommended dose of ampicillin for a child is 150 mg/kg/day in divided doses every 6 hours. It is prepared so that the concentration is 125mg/5ml. How many mls should a 57 Lb child receive per dose?
2. A prescription calls for 1/3 pound of a cream. How many grams will you dispense?
3. Hydrocortisone 1% gel comes in a 1 1/2 ounce tube. How many milligrams are in this product?
4. You fill a prescription for 8 ounces of Tylenol with codeine elixir from the new pint bottle on the shelf. How many milliliters are left in the stock bottle?
5. Digoxin for injection comes in a concentration of 0.5mg/2ml. Express this in mcg/ml.
6. The dose of tobramycin for a specific patient is 2.5mg/kg. Tobramycin for injection comes in a concentration of 40mg/ml. How many milliliters of tobramycin should be used for a dose for this 215 Lb patient?
7. How many 85 mg tablets can be produced from 1.25 kg of drug?
8. How many teaspoonsful of a cough syrup can be obtained from a 10 ounce bottle?
9. Azithromycin suspension comes in a concentration of 200 mg/5 ml . If a child is to take 250 mg daily for 5 days, how many mls should be dispensed?
10. How many grams of a drug should be dissolved in 100 ml of water to make a 15% (w/w) solution?
11. If 25 grams of sodium chloride are dissolved in 350 ml of water, what is the percentage strength (w/w) of the solution?
12. One lb of a fungicidal ointment contains 9.08 g of undecylenic acid. Calculate the percentage (w/w) of undecylenic acid in the ointment.
13. The intravenous dose of mannitol is 1.5 g per kg of body weight, administered as a 15% (w/v) solution. How many milliliters of the solution should be administered to a 175 lb patient?
14. Methotrexate sodium injection contains 25 mg methotrexate sodium per milliliter. Express the percent concentration of methotrexate in the injection.
15. If 425 g of sucrose are dissolved in enough water to make 500 ml, what is the percentage strength (w/v) of the solution?
16. How many milliliters of a 0.9% (w/v) sodium chloride solution can be made from 1 lb of sodium chloride?
17. For children under 12 years old, acetaminophen (Tylenol) should be dosed at 10mg/kg/dose. How many mg of acetaminophen should a 6 year old, 57 lb child receive per dose?
18. For the following prescription, calculate how many days the dispensed amount will last.
Carafate suspension (500mg/tsp)
Disp. 1 pint
Sig: 1 gm qid, ac & hs
19. The recommended dose of gentamicin for a specific patient is 2 mg/kg/dose. The patient weighs 153 lb, and the gentamicin vials contain 40 mg/ml of drug. How many mls should the patient receive per dose?
20. From the following formula, calculate the quantities required to make 180mL of benzyl benzoate lotion.
Benzyl Benzoate 250 mL
Triethanolamine 5 mL
Oleic Acid 20 mL
Purified water, qs ad 1000 mL
21. From the following formula, calculate the number of grams of each ingredient required to make 1 lb of the ointment.
Salicylic Acid 0.5 part
Precipitated Sulfur 4.5 parts
Hydrophilic ointment 35 parts
22. From the following formula, calculate the number of grams of each ingredient required to make 454 g of the ointment.
Salicylic Acid 0.5 part
Precipitated Sulfur 4.5 parts
Hydrophilic Ointment 35.0 parts
23. What is the percent (w/v) of a 1:10,000 epinephrine solution?
24. You are given 40 ml of a 0.5% (w/v) morphine solution and asked to dilute it with water to make a 1:1000 solution. How many milliliters of water do you need to add to prepare the 1:1000 dilution?
25. You need to prepare 100 mls of hydromorphone IV that is to contain 1 mg hydromorphone per ml. How many milliliters of hydromorphone 4 mg/ml and how many milliliters of diluent should you use?
26. A solution contains 10 mg% of K+ ions. Express this concentration in terms of milliequivalents per liter.
27. The normal magnesium (Mg++) level in blood plasma is 2.5 mEq/L. Express this concentration in terms of milligrams percent.
28. A person is to receive 2 mEq sodium chloride per kilogram of body weight. If the person weighs 132 lb, how many milliliters of an 0.9% sterile solution of sodium chloride should be administered?
29. What is the osmolarity of a solution containing 5% dextrose and 0.45% sodium chloride? (mw of dextrose = 180, mw of NaCl = 58)
Conversions you should know by now:
2.2 lb/kg 5ml/tsp 15 ml/TBSP
30 ml/fl. oz 28-30 gm/oz (wt) 454 gm/lb
60-65 mg/gr 3785 ml/gal 473-480ml/pint