Additional Drug Dosage Problems

 

Taken from Practical Problems in Mathematics for Health Occupations, Louise Simmers, Delmar Publishers Inc., 1996; 213 – 214, 216 – 218, 220 – 223, 230-233. These problems are optional and are for you to practice drug calculations with. Do as many of these problems as needed to become comfortable with drug calculations.

 

ENGLISH – METRIC EQUIVALENTS

1 drop (gtt)            =       0.0667 milliliter (ml)

15 drops (gtt)        =       1.0 milliliter (ml)

1 teaspoon (tsp)    =       5.0 milliliters (ml)

3 teaspoons =       1 tablespoon (tbsp)         =       15.0 milliliters (ml)

1 ounce (oz)          =       30.0 milliliters (ml)

8 ounces      =       1 cup (cp)             =       240.0 milliliters (ml)

2 cups (cp)  =       1 pint (pt)              =       500.0 milliliters (ml)

2 pints (pt)   =       1 quart (qt)            =       1,000 milliliters (ml)

 

These equivalents are in addition to the ones given out in lab 1.Show all work on a separate piece of paper.

 

Example #1: A doctor orders 300 mg of Terramycin. Capsules contain 100 mg per capsule. How many capsules should the patient receive?

 

300 mg       X       1 capsule       =       3 capsules

                          100 mg

 

 

Example #2: A doctor orders streptomycin 500 mg IM. The dosage available for use contains 1 g per 2 ml. How many ml should be injected?

Hint:All units must be in the same unit of measurement.

Convert 1 g to mg.

1 g = 1,000 mg

 

2 ml       X            1 g           X       500 mg       = 1 ml

1 g                 1000 mg            dose

 

 

Example #3: A 66 pound (lb) child is to receive 25 mg/kg/day of Tetracycline tid (three times a day). Tetracycline is available in 100 mg and 250 mg capsules. How many capsules should the child be given per dose?

First convert the weight in pounds to kilograms.

66 lb       X       1 kg        =       30 kg

                      2.2 lb

 

Second calculate the number of mg the child needs to get the total dose for the day.

30 kg       X       25 mg       =     750 mg

                      1 kg                       day

 

Third calculate the mg needed per dose. In this case the child will receive 3 doses per day.

750 mg       X      1 day         = 250 mg/dose

   day              3 doses

 

Fourth calculate the number of capsules it’ll take.

250 mg       X       1 capsule       =       1 capsules

  dose                 250 mg               dose

 

You could also do this all in two lines:

66 lb    X    1 kg    X    25 mg    = 750 mg

                2.2 lb          1 kg                day

 

750 mg     X      1 day    X    1 capsule    =     1 capsule

   day           3 doses        250 mg            dose

 

 

Example #4: The doctor orders 1000 ml of 5% dextrose in water (D5W) to be infused in 8 hours. The drop factor of the infusion set is calibrated at 20 gtt/ml. What is the flow rate in drops per minute?

 

Flow Rate = Volume X Drop Factor X Time

(gtt/min)         (ml/hr)        (gtt/ml)     (1 hr/60 min)

 

Flow Rate = 1000 ml X 20 gtt X 1 hr  

    8 hr       1 ml      60 min

Flow Rate = 41.66 gtt, round this to 42 drops per minute

 

 

Example #5: Calculate the infusion time for an IV of 1000 ml of D5W infusing at 50 ml/hour.

Infusion Time = Total volume to infuse

      ml/hour being infused

 

Infusion Time = 1000 ml X 1 hr     = 20 hours

  50 ml

 

 

Easiest Problems

 

1.     A doctor orders 600 mg of potassium chloride (KCl). Tablets available contain 300 mg per tablet. How many tablets should be given?

 

2.     A doctor orders 500 mg of Amoxicillin. Capsules available contain 250 mg per capsule. How many capsules should be given?

 

3.     A doctor orders 250 mg of Sulfasalazine. Tablets available contain 500 mg per tablet. How many tablets should be given?

 

4.     A doctor orders 15 mg of Prednisolone. Tablets available contain 5 mg per tablet. How many tablets should be given?

 

5.     A doctor orders 50 mg of Vistaril̉ suspension. It is available in 25 mg per 5 ml. How many ml should be given?

 

6.     A doctor orders 50,000 units of Nilstat̉ suspension. It is available as 100,000 units in 2 ml. How many ml should be given?

 

7.     A doctor orders 10 mg of Nembutal̉ elixir. It is available as 20 mg in 5 ml. How many ml should be given?

 

8.     A doctor orders 0.125 mg of Digoxin. It is available in 0.25 mg tablets. How many tablets should be given?

 

9.     A doctor orders 1 g of Keflex̉. It is available in 250 mg capsules. How many capsules should be given?

 

10. A doctor orders 0.1 g of meprobamate. It is available in 200 mg tablets. How many tablets should be given?

 

11. A doctor orders 20 mg of Simethicone. It is available as 0.04 g per 0.6 ml. How many ml should be given?

 

12. A doctor orders 0.25 mg of Levsin̉ drops. It is available as 0.125 mg per ml. How many drops should be given?

 

13. A doctor orders 5 ml of Phenobarbital Elixir. It is available as 30 mg per 7.5 ml. How many mg does the patient receive?

 

Harder Problems

 

14. A doctor orders 75 mg of Demerol̉ IM (intramuscularly) q4h (every four hours) prn (whenever necessary) for pain. It is available as 50 mg per ml. How many ml should be injected with each shot?

 

15. A doctor orders Librium̉ 50 mg IM. It is available as 100 mg per 2 ml. How many ml should be injected?

 

16. A doctor orders 25 mg of Dilantin̉ IM. It is available as 50 mg per ml. How many ml should be injected.

 

17. A doctor orders 20 mEq (milliequivalents) of potassium chloride (KCl) IV (intravenously). It is available as 40 mEq per 20 ml. How many ml should be injected?

 

18. A doctor orders 1,000 mg of Amikin̉ IM. It is available as 500 mg per 2 ml. How many ml should be injected?

 

19. A doctor orders 250 mg of Pollycillin-N̉ IM. It is available in 1,000 mg per 5 ml. How many ml should be injected?

 

20. A doctor orders 100,000 units (U) of penicillin IM. It is available in 5,000,000 U per 25 ml. How many ml should be injected?

 

21. A doctor orders an injection of 45 µg of vitamin B12. It is available as 300 µg in 10 ml. How many ml should be injected?

 

22. A doctor orders 10 mg of Valium̉ IM. It is available as 5 mg per ml. How many ml should be injected?

 

23. A doctor orders 50,000 units (U) of Heparin IV. It is available as 40,000 U per 2 ml. How many ml should be injected?

 

24. A doctor orders 60 mg of Gentamicin Sulfate IM. It is available as 80 mg per 2 ml. How many ml should be injected?

 

25. A doctor orders 0.1 mg of Atropine IM. It is available as 0.4 mg per ml. How many ml should be injected?

 

26. A doctor orders 250 mg of Keflin̉ IM. It is available as 1 g per 10 ml. How many ml should be injected?

 

27. A patient is given 1.5 ml of Kefsol̉ IM. It is available as 1 g per 2 ml.

a.      How many grams of Kefsol̉ are injected?

b.     How many mg of Kefsol̉ are injected?

 

28. A patient is given 15 ml of Isuprel̉ in an IV drip. It is available as 1 mg in 5 ml. How many mg are injected?

 

29. A patient is given 2 ml of Dilaudid̉ IM. It is available as 50 mg per 5 ml. How many mg are injected?

 

Hardest Problems

 

30. The recommended dosage for Meperidine is 6 mg/kg/day for pain. A child weighing 88 pounds can receive the medication q4h (every 4 hours).

a.      How many mg can the child receive per day?

b.     How many mg can the child receive per dose? (Hint: Divide 24 hours by 4 hours to find the total number of doses per day.)

 

31. The recommended dose for Sulfasalazine is 30 mg/kg/day. A patient weighing 110 pounds is to take the medication tid (three times a day).

a.      How many mg can the patient receive per day?

b.     How many mg can the patient receive per dose? (Hint: Remember the medication is tid.)

 

32. A child weighing 44 pounds is to receive Cefadroxil q12 (every 12 hours). The recommended dose is 30 mg/kg/day.

a.      How many mg can the child receive per day?

b.     How many mg can the child receive per dose?

 

33. The recommended dose for Ancef̉ is 100 mg/kg/day. A patient weighing 124 pounds is to take the medication qid (four times a day).

a.      How many mg can the patient receive per day?

b.     How many mg can the patient receive per dose?

 

34. The recommended dose for Vancocin̉ is 40 mg/kg/day. A patient weighing 246 pounds is to take the medication q6h (every 6 hours).

a.      How many mg can the patient receive per day?

b.     How many mg can the patient receive per dose?

 

35. The recommended dose for Rondomycin̉ is 10 mg/kg/day. A patient weighing 132 pounds is to take the medication qid (four times a day). Rondomycin® is available in 150 mg capsules.

a.      How many mg can the patient receive per dose?

b.     How many capsules can the patient receive per dose?

 

36. The recommended dose for Ampicillin̉ is 50 mg/kg/day. A child weighing 66 pounds is to take the medication q8h (every 8 hours). Ampicillin® is available as 250 mg per 5 ml.

a.      How many mg can the child receive per dose?

b.     How many ml should the child receive per dose?

 

37. The recommended dose for Kanamycin is 15 mg/kg/day for an IM injection. A patient weighing 220 pounds is to receive an IM injection q12h (every 12 hours). Kanamycin for injection contains 500 mg per 2 ml.

a.      How many mg can the patient receive per injection?

b.     How many ml can the patient receive per injection?

 

38. The recommended dose for Gentrisin̉ is 150 mg/kg/day. An infant weighing 22 pounds is to take the medication q4h (every four hours). Gentrisin® is available as 0.5 grams per 5 ml.

a.      How many mg does the infant receive per dose?

b.     How many ml does the infant receive per dose?

 

39. The recommended dose for Chloromycetin̉ is 50 mg/kg/day. A patient weighing 176 pounds is to take the medication q6h. Chloromycetin® is available as 0.25 g capsules.

a.      How many mg can the patient receive per dose?

b.     How many capsules can the patient receive per dose?

 

40. The recommended dose for Ancobon̉ is 50 - 150 mg/kg/day. A patient weighing 162 pounds is to take the medication q6h. Ancobon® is available in 250 mg capsules.

a.      What is the range in mg the patient can  receive per dose?

b.     What is the range in number of capsules the patient can receive per dose?

 

41. The recommended dose for Aminophylline is 12 mg/kg/day divided into 4 equal doses. A child weighing 41 pounds is to take the medication qid (four times a day). Aminophylline is available in 100 mg tablets.

a.      How many mg can the child receive per dose?

b.     How many tablets can the child receive per dose?

 

42. The recommended dose for Mintezol̉ suspension is 0.01 g/kg/day. A child weighing 39 pounds is to take the medication tid (three times a day) after meals (pc). Mintezol® is available as 500 mg per 5 ml.

a.      How many mg can the child receive per dose?

b.     How many ml can the child receive per dose?

 

43. The recommended dose for Streptomycin is 8 - 20 mg/pound/day. A patient weighing 94 pounds is to receive 2 ml injected every 6 hours. Streptomycin is available as 1 g per 5 ml and comes in a 5 ml multiple dose vial..

a.      Is the injection ordered within the recommended dosage?

b.     How many mg will the patient receive per day?

 

44. The recommended dose for Theophylline is 5 -6 mg/pound/day. A patient weighing 156 pounds is to take the medication bid (twice a day). Theophylline is available as 200 mg tablets. How many tablets should the patient take?

 

45. The recommended dose for Midazolam is 0.07 – 0.08 mg/kg IM one hour before surgery. It is available as 5 mg per ml and must be given in exact dosage. How many ml should be injected into a 182 pound patient? Round off to the nearest one-tenth of a ml.

 

Infusion Problems

 

46. A doctor orders an IV of D5W to run at 100 ml per hour. The drop factor of the infusion set is 10 gtt/ml. What is the flow rate?

 

47. An IV of Ringer’s Lactate Solution (LRS) is to run at 50 ml per hour. The drop factor of the infusion set is 15 gtt/ml. What is the flow rate?

 

48. An antibiotic is mixed as 50 ml of IV solution. It is to infuse in 1 hour. The drop factor of the infusion set is 60 gtt/ml. What is the flow rate?

 

49. Calculate the flow rate for an IV of 500 ml of Normal Saline (NS) to be infused in 8 hours. The drop factor of the infusion set is 20 gtt/ml.

 

50. What is the flow rate for an IV of 1000 ml of 0.45% NS to infuse in a 24 hour period. The drop factor of the infusion set is 10 gtt/ml.

 

51. A doctor orders 2000 ml of LRS to infuse in a 24 hour period. The drop factor of the infusion set is 20 gtt/ml. What is the flow rate?

 

52. An IV of 500 ml of Dextrose in Normal Saline (D/NS) should be infused in 4 hours. The drop factor of the infusion set is 15 gtt/ml. What is the flow rate?

 

53. A doctor orders 2 pints of blood be infused in 10 hours. The drop factor of the infusion set is 10 gtt/ml. What is the flow rate? (Hint: One pint = 500 ml.)

 

54. An antibiotic IV solution contains 20 ml of solution to be infused in 15 minutes. The drop factor of the infusion set is 60 gtt/ml. What is the flow rate? (Hint: Fifteen minutes equals ¼ hour.)

 

55. An IV containing Heparin in 500 ml of NS is to infuse at 30 ml per hour. What is the infusion time?

 

56. An IV containing Xylocaine in 1000 ml of 5% Dextrose in Water is to infuse at 20 ml per hour. What is the infusion time?

 

57. An IV containing Heparin in 250 ml of NS is infusing at 40 drops per minute. The drop factor of the infusion set is 60 gtt/ml. What is the infusion time?

 

58. Tetracycline is prepared in 50 ml of an IV solution. It is infusing at 30 drops per minute. The drop factor of the infusion set is 20 gtt/ml. What is the infusion time?

 

59. A doctor orders 1 pint of blood followed by 500 ml NS. It is infusing at 60 drops per minute. The drop factor of the infusion set is 15 gtt/ml. What is the infusion time for both solutions?

 

60. The doctor orders one pint of blood to infuse in 2 hours. This is to be followed by 1000 ml of NS to infuse at 30 drops per minute. The drop factor of the infusion set is 15 gtt/ml.

a.      What is the flow rate for the blood?

b.     What is the total infusion time for the two IV solutions?

 

61. A doctor orders 40 ml of an IV solution containing Ampicillin to run in 30 minutes. This is to be followed by 500 ml of NS to infuse at 50 drops per minute. The drop factor of the infusion set is 20 gtt/ml.

a.      What is the flow rate for the Ampicillin solution?

b.     What is the total infusion time for the two IV solutions?