Post on 19-Jun-2015
Calculate with Confidence5th edition
Gray Morris
Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
Apothecary and Household Systems
Unit Two: Chapter 7
Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
3Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
Apothecary & Household: ObjectivesAfter reviewing this chapter, you should be able to:
1. State common apothecary equivalents2. State common household equivalents3. State specific apothecary system rules4. State specific household system rules5. Identify apothecary symbols &
measures6. Identify household symbols & measures
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Apothecary: BackgroundEnglish origin—considered to be oldestAlso called “Fraction System”Notations and Roman numerals are potentially
confusingNotations included in TJC “Do Not Use” list
TJC recommends they NOT be used in medication administration. Discouraged by ISMP.
Found on labels of older medicationsAlways convert to metric
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6Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
Apothecary: Particulars1. Abbreviation is written before unit of
measure (six grains = gr vi or gr 6)2. Roman and/or Arabic numbers are used3. Fractions indicate quantities less than 1
gr ¾
4. Fraction ½ is indicated as ss or ss—do not use
5. Can combine whole and fraction (gr 7½)
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Apothecary: Units of MeasureMinims and drams (Ʒ) no longer used – some
syringes or cups may still have markingsNurse needs to know
1 pint = 16 fluid ounces 1 quart = 32 fluid ounces = 2 pints
Weight Grain = gr Be careful not to confuse gr with g for gram Metric equivalents: gr 15 = 1 g and gr 1 = 60-65 mg
Most meds are based on the equivalent gr 1 = 60 mg
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9Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
Apothecary: Units of Measure
(cont’d)Volume
Ounce = oz Metric equivalent: 1 oz = 30 mLMedicine cups are 1 oz capacity
Although apothecary measures may still be on syringes and containers, they should always be converted to metric
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Household: BackgroundOld system and least accurateCapacities of glasses and utensils vary by
brand unless CALIBRATEDAdvise use of droppers and devices
provided with medications for accurate dosing
Memorize:1 teaspoon (t, tsp) = 5 mL1 tablespoon (T, tbs) = 15 mL1 measuring cup = 8 oz
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Households: Particulars1. Some are same as apothecary measures
Pints and quarts
2. No standard rules for expressing measures
3. Cookbook abbreviations commonly used4. Arabic numerals and fractions are used5. Smallest unit of measure is drop (gtt)
Never use as unit of measure unless delivery device is calibrated (e.g., medicine dropper or IV tubing)
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13Mosby items and derived items © 2010 by Mosby, Inc., an affiliate of Elsevier Inc.
Household: SolutionsUse calibrated spoons and measuring cups!
Normal Saline (0.9%)2 teaspoons salt in 4 cups of water
Acetic Acid (0.25%)3 tablespoons of white vinegar in 4 cups of
waterUsed for some wound/dressing care and for
cleaning equipment