#HAPTER 14 s Medications and 1

Calculations
Pileo, Cheska M. Section 14A—Systems of Measurement with Conversion

Metric and Household Systems

Match the term in Column I with the appropriate abbreviation in Column II.

Column I Column II
B 1. Gram a. T
b. g
F 2. Milligram
c. mL
G 3. Liter d. gr
e. fl oz
C 4. Milliliter
f. mg
K 5. Kilogram g. L or l
h. fl dr
L 6. Microgram
i. minim
M 7. Nanogram j. gtt
k. kg
R 8. Meter
l. mcg
D 9. Grain m. ng
n. t
E 10. Fluid ounce
o. c
H 11. Fluid dram p. pt
q. qt
Q 12. Quart
r. m
P 13. Pint
I 14. Minim
C 15. Cup
A 16. Tablespoon
N 17. Teaspoon
J 18. Drops

Complete the following. Complete the unit equivalent for the following
measurements.
19. The most frequently used conversions within the
metric system are: 20. 3 grams =3000 milligrams
A. 1 g = 1000 mg 21. 1.5 liters =1500 milliliters
B. 1 L =1000 mL 22. 0.1 gram =100 milligrams
C. 1 mg = 1000 mcg 23. 2500 milliliters = 2.5 liters
24. 250 milliliters = .25 liter
25. 500 milligrams =5 gram
26. 2 quarts = 4 pints
27. 2 pints = 32 fluid ounces
28. 1½ quarts = 48 fluid ounces
29. 32 fluid ounces = 2 pints
30. 2 fluid ounces = 16 fluid drams

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4O #HAPTER 14 s Medications and Calculations

Metric, Apothecary, and Household Systems

31. When converting a unit of measurement from one system to another, convert to the unit on the drug container.
Example:
Order: V-Cillin K 0.5 g, PO,
q8h. Available:

Convert gram to milligram (unit of measurement to unit of measurement)

Convert the following units of measurement to metric, apothecary, and household equivalents. Refer to
Table 14A-3 in the textbook as needed.

32. 1 g = 1000 mg, or 15.43 gr

33. 0.5 g = 500 mg, or 7.72 gr

34. 0.1 g = 100 mg, or 1.54 gr

35. 1 gr = 64.8 mg

36. 0.4 mg = 0.0062 gr

37. 1 L = 1000 mL, or 1.06 qt

38. 240 mL = 8.12 fl oz, or 1 glass

39. 30 mL = 1.02 fl oz, or 2 T, or 6 t

40. 5 mL = 1 t

41. 3 T = 1.5 fl oz, or 9 t

42. 5 fl oz =147.87 mL, or 10 T

 #HAPTER 14 s Medications and 41
Calculations

Section 14B—Methods for Calculation

Select the best response.

1. Before calculating drug dosages, all units of measurement must be converted to one system. Which system should
the nurse use?
a. Any one he or she prefers.
b. One that fits with how he or she will administer the drug.
c. One that is easy to convert to.
d. The one on the drug label.

Interpretation of Drug Label

Give information concerning the following drug label.

2. What is the brand name of this drug?

a. Ampicillin
b. Principen

3. What is the generic name of this drug?

a. Ampicillin
b. Principen

4. What is the dosage of this drug? 250 mg/5 mL

5. What is the form of this drug?

a. Tablet
b. Liquid
c. Capsule
d. Suspension

Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
Methods for Drug Calculation

Use the basic formula, ratio and proportion, or dimensional analysis methods to calculate the following drug
problems.

6. Order: ritonavir (Norvir) 0.2 g, PO, b.i.d.

Available:

A. Is conversion needed to give this medication?

a. No; it may be administered in grams.
b. No; the pill may be broken if needed.
c. Yes; it should be converted to grains.
d. Yes; it should be converted to milligrams.

B. How much of this medication should the nurse administer? Solution: 200 mg/100 mg x 1 capsule = 2 capsules
a. 1 capsule
b. 2 capsules
c. 3 capsules
d. 4 capsules

7. Order: Benadryl (diphenhydramine) 25 mg, PO, q6h, PRN.

Available: Benadryl 12.5 mg/5 mL

A. Is conversion needed to give this drug?

a. No; it can be administered in milligrams as ordered.
b. No; you cannot mix mg and mL.
c. Yes; it should be converted to grains.
d. Yes; it should be converted to grams.

12.5 25 mg
B. How many mL should the nurse give? Calculate the drug problem using the method selected. x = 10 mL
5 mL x mL
a. 5 mL
b. 10 mL
c. 15 mL
d. 20 mL
8. Order: clarithromycin (Biaxin) 0.25 g, PO, b.i.d.
Available:

A. Is conversion needed to give this medication?

a. No; it may be administered in grams.
b. No; you cannot mix mg and mL.
c. Yes; it should be converted to grains.
d. Yes; it should be converted to milligrams.

250 mg 125 m g
B. How many mL should be administered? Solution: x = 10 mL
x mL 5 mL
a. 5 mL
b. 10 mL
c. 15 mL
d. 20 mL

9. Order: hydroxyzine (Vistaril) 100 mg, IM,

q6h. Available:

50 mg 100 mg
How many mL should be administered? x = 2 mL
1 mL x mL
a. ½ mL
b. 1 mL
c. 1½ mL
d. 2 mL

10. Order: cefazolin (Kefzol) 500 mg, IM, q8h.

Available: (NOTE: Redi-vial container has diluent in a separate compartment of the vial. Push plug to release
dilu- ent for reconstitution.)

1000 mg 50 0 mg
How many mL should be administered? Solution: x = 1.5 mL
3 mL x mL
a. 1 mL
b. 1.5 mL
c. 2 mL
d. 2.5 mL
Additional Dimensional Analysis

11. Order: acarbose (Precose) 50 mg, PO, t.i.d.

Available:

A. How many tablets should be administered? Sol: 50 mg / 25 mg x 1 tablet = 2 tabs

a. 1 tablet
b. 2 tablets
c. 3 tablets
d. 4 tablets

B. Which drug label(s) should be selected?

a. 25 mg per tablet
b. 100 mg per tablet

12. Order: losartan potassium (Cozaar) 0.1 g,

daily. Available:

How many tablets should the patient receive per day? Sol. 100 mg/ 50 mg x 1 tablet = 2 tabs
a. 1 tablet
b. 2 tablets
c. 3 tablets
d. 4 tablets
 Section 14C—Calculations of Oral Dosages
Drug calculation problems include oral dosages for adults.

1. Order: benztropine (Cogentin) 1 mg, PO,

daily. Available:

How many tablets should be administered? Solution: 1 mg / 0.5 mg x 1 tablet = 2 tabs

a. 1 tablet
b. 1½ tablets
c. 2 tablets
d. 2½ tablets

2. Order: codeine sulfate 60 mg, PO, q6h, PRN.

Available: Tablets are available in two forms (see drug labels).

Which form should be used? Why?

a. 15-mg tablets; the patient will take more pills.
b. 30-mg tablets; the patient will take fewer pills.
c. 15-mg tablets; the patient will take fewer pills.
d. 30-mg tablets; the patient will take more pills.

3. Order: propranolol (Inderal) 15 mg, PO, q6h.

Available: propranolol 10-mg and 20-mg
tablets.

A. Which tablet strength should be administered?

a. 10-mg tablets
b. 20-mg tablets

B. How many tablets should be administered?

a. 1 tablet
b. 1½ tablets
c. 2 tablets
d. 2½ tablets
4 #HAPTER 14 s Medications and Calculations

4. Order: penicillin V potassium 250 mg, PO, q6h.

Available: (NOTE: The generic name of the drug may be given instead of the brand name. Check the label for
both names.)

How many tablets should be administered? Sol: 250 mg / 500 mg x 1 tablet = 0.5 tablet
a. ½ tablet
b. 1 tablet
c. 1½ tablets
d. 2 tablets

5. Order: cimetidine (Tagamet) 600 mg, PO, hour of

sleep. Available:

How many tablets should be administered? Sol: 600 mg / 200 mg x 1 tablet = 3 tablets
a. 1 tablet
b. 2 tablets
c. 3 tablets
d. 4 tablets

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 #HAPTER 14 s Medications and 47
Calculations

6. Order: verapamil 60 mg, PO, q.i.d.

Available:

A. Which strength of verapamil should be selected?

a. 120-mg tablet
b. 80-mg tablet

B. Tablets are scored. How many tablets should be administered?

a. ½ tablet
b. 1 tablet
c. 1½ tablets
d. 2 tablets

7. Order: Artane SR 10 mg, PO,

daily. Available:

A. Which container of Artane 5 mg should be selected?

a. 5-mg sustained-release tablets
b. 5-mg tablets

B. How many tablet(s)/sequel(s) should be administered? Sol: 10 mg / 5 mg x 1 tab = 2 tablets

a. ½ tablet
b. 1 tablet
c. 1½ tablets
d. 2 tablets
48 #HAPTER 14 s Medications and Calculations

8. Order: trazodone (Desyrel) 150 mg, PO, daily.

Available: Desyrel in 50-mg tablets and 100-mg
tablets.

A. How many tablets should be administered if the 50-mg tablet is used?

a. 1 tablet
b. 2 tablets
c. 3 tablets
d. 4 tablets

B. How many tablets should be administered if the 100-mg tablet is used?

a. ½ tablet
b. 1 tablet
c. 1½ tablets
d. 2 tablets

9. Order: Coumadin (warfarin) 7.5 mg, PO,

daily. Available: (NOTE: Tablet is scored.)

A. Which container of Coumadin should be selected?

a. Coumadin 2 mg
b. Coumadin 4 mg
c. Coumadin 5 mg

B. How many tablets should be administered?

a. ½ tablet
b. 1 tablet
c. 1½ tablets
d. 2 tablets

10. Order: lithium carbonate, 300 mg, PO, t.i.d.

Available: lithium carbonate in 150- and 300-mg capsules, and 300-mg tablets. The patient’s lithium level is
1.8 mEq/L (normal value is 0.5-1.5 mEq/L).

What is the best action by the nurse?

a. Give 150 mg (half the dose).
b. Give 300-mg tablet and not the capsule.
c. Advise the patient not to take the dose for a week.
d. Withhold the drug and contact the health care provider.
 11. Order: carvedilol (Coreg) 25 mg, PO, b.i.d.
Available:

A. How many tablets should be administered per dose? Sol. 25 mg / 6.25 mg x 1 tab = 4 tablets
e. 3 tablets
f. 4 tablets
g. 5 tablets
h. 6 tablets

B. How many tablets should the patient receive in 24 hours?

i. 4 tablets
ii. 6 tablets
iii. 8 tablets
iv. 10 tablets

12. Order: azithromycin (Zithromax) 400 mg, daily first day, then 200 mg, daily next 4 days. Available:

i. How many mL should be administered the first day?

j. 10 mL/day
k. 15 mL/day
l. 20 mL/day
m. 25 mL/day

b. How many mL should be administered per day for the next 4 days?
i. 5 mL/day
ii. 8 mL/day
iii. 10 mL/day
iv. 15 mL/day
5O #HAPTER 14 s Medications and
Calculations

13. Order: trihexyphenidyl (Artane) Elixir 1

mg, PO, b.i.d. Available: Artane 2 mg/5
mL.

2 mg 1 mg
What amount should be administered? Sol: x = 2.5 mL
5 mL x mL
a. 1/2 teaspoon
b. 2 teaspoons
c. 3 teaspoons
d. 4 teaspoons

14. Order: doxycycline (Vibra-Tabs), 0.2 g, PO first day, then 0.1 g, PO daily
for 6 days. Available:

How many tablets should the patient receive the first day, then how many tablets per day for 6 days?
a. 2 for the first day and then 2 tablets for each of the following days
b. 2 for the first day and then 1 tablet for each of the following days
c. 3 for the first day and then 2 tablets for each of the following days
d. 3 for the first day and then 1 tablet for each of the following days

15. Order: digoxin 0.25 mg, PO, daily.

Available: digoxin (Lanoxin) 0.125-mg tablets. The drug comes in 0.25-mg tablets, but that strength of tablet is
not available.

How many tablets should be administered? 0.25 mg / 0.125 mg x 1 Tab = 2 Tablets

a. 1 tablet
b. 1½ tablets
c. 2 tablets

Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
 #HAPTER 14 s Medications and 51
d. 2½ tablets Calculations

Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
16. A patient is scheduled to take Lanoxin 0.25 mg. The hospital is currently out of stock of Lanoxin 0.25 and only
has 0.125-mg doses on hand. The patient is concerned as she receives the pills because they are a different color
and a different amount from what she takes daily. When the patient questions the tablets, what is the nurse’s
best response?
a. “Please don’t worry; it is because we use generic drugs.”
b. “Please don’t worry; I calculated this carefully and it is your regular dose.”
c. “We don’t have the 0.25-mg tablets available, so you must take two pills of a different strength.”
d. “You are right, this is the wrong dosage. I will be right back with the correct one.”

17. Order: Augmentin, 400 mg, PO,

q6h. Available:

250 mg 400 mg
How many mL should be administered? Sol: x = 8 mL
5 mL x mL
a. 4 mL
b. 8 mL
c. 12 mL
d. 16 mL

18. Order: cefadroxil (Duricef) 1 g, PO,

daily. Available:

500 mg 1000 m g
How many mL should be administered? Sol: x = 10 mL
5 mL x mL
a. 5 mL
b. 10 mL
c. 15 mL
d. 20 mL
 19. Order: prazosin (Minipress) 10 mg, PO,
daily. Available: prazosin 1-mg, 2-mg,
and 5-mg tablets.

Which tablet should be selected, and how many should be administered?

a. The 1-mg tablet; 5 pills should be given.
b. The 5-mg tablets; 2 pills should be given.
c. The 5-mg tablets; 5 pills should be given.
d. The 2-mg tablets; 3 pills should be given.

20. Order: carbidopa-levodopa (Sinemet), 12.5-125 mg, PO,

b.i.d. Available: Sinemet 25-100–mg, 25-250–mg, and 10-
100–mg tablets.

Which tablet should be selected, and how many should be administered?

a. The 25-100–mg tablet; ½ tablet should be given.
b. The 25-100–mg tablet; 1 tablet should be given.
c. The 10-100–mg tablet; 2 tablets should be given.
d. The 10-100–mg tablet; 1 tablet should be given.
e. The 25-250–mg tablet; ½ tablet should be given.
f. The 25-250–mg tablet; 1 tablet should be given.

21. Order: Ceclor 150

mg, PO, q8h.
Available:

125 mg 15 0 mg
How many mL should the patient receive per dose? x = 6 mL
5 mL x mL
a. 4 mL
b. 6 mL
c. 8 mL
d. 10 mL
22. Order: ampicillin (Principen) 0.5
g, PO, q6h. Available:

250 mg 5 00 mg
How many mL should the patient receive per dose? x = 10 mL
5 mL x mL
a. 10 mL
b. 15 mL
c. 20 mL
d. 25 mL