drug calculations making it easy. class outline 1) review roman numerals 2) review apothecary...
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DRUG CALCULATIONS
MAKING IT EASY
CLASS OUTLINE1) review roman numerals2) review apothecary measurements3) review conversions4) review 3 steps to dosage
calculations5) practice, practice, practice
Plugging in to MemoryRoman Numerals
APOTHECARY MEASURES What are we talking about?
CONVERSIONS - WITHIN SYSTEMS
- BETWEEN DIFFERENT SYSTEMS
WITHIN SYSTEMS
MEMORIZE:
1 gram (g or G) = 1000 milligrams (mg)1 liter (l or L) = 1000 milliliters (ml or
mL)3 teaspoons (t) = 1 tablespoon (T) 1 cubic centimeter (cc) = 1 milliliter (ml)
BETWEEN SYSTEMS
MEMORIZE: 1 gram (G, GM, gm) = 15 grains (gr) 60 milligrams (mg) = 1 grain (gr) 1 tablespoon (T) = 15 ml 1 kilogram (kg) = 2.2 pounds (lb) 1 ounce (oz) = 30 ml or 30 cc 1 cc = 15 drops (gtt) or 15 minims (mx) 1 inch (in) = 2.5 centimeters (cm)
STEPS TO CONVERSION
WITHIN SYSTEMS1) Write down what you know in a ratio
or fraction format:
Example: 1 Gram 1000 milligrams
2) Write down what you desire in a ratio or fraction format to complete the proportion:
Example: 3 Grams x milligrams
Remember:
The numerator and denominator must be the same unit of measurement
The unknown value is referred to as “x”
The completed proportion:
1 Gram 3 Grams 1000 mg : : x milligrams
Cross multiply
1 GM x X mg(s) = 3 GM x 1000 mg Drop the terms used for units of
measurement: 1 X = 3(1000)Solve for X: divide both sides of the
equation by the number preceding X:X = 3000 1 1 X = 3000
BETWEEN SYSTEMS
1) Write down what you know in a fraction format:
15 grains 1 gram
2) Complete the proportion by writing down what you desire:
15 grains 30 grains 1 gram : : X grams
HINT: Keep the units of measurements in the correct spaces!
Drop the units of measurement Cross multiply
15 x X = 30 x 1 15X = 30
Solve for X: Divide each side by the number in front of X : X = 2 ANS: 2 Grams
VOILA!!
3 STEPS TO DOSAGE CALCULATION:1) Convert to units of same system and
similar unit2) STOP AND THINK3) Desired over amount on hand times
quantity
EX: desired amount on hand x quantity
SAMPLE PROBLEMS 1) Convert: 300 mg to grams
2) Convert: 120 mg to grains
3) Convert: 30 gr to grams
4) A child who weighs 55 pounds weighs ____ kilograms?
5) A patient is restricted to four 8-ounce glasses of water per day. The nurse knows that the patient’s fluid intake is restricted to ____ mls per day.
6) The nurse administered aspirin gr v. She knew this was equivalent to _____milligrams(s).
7) Potassium chloride tablets are available in 300 mg doses. The physician prescribed gr v. Give ____ tablet(s).
8) The physician prescribed Capoten, 1.5 grams daily in three equal doses, for hypertension. The nurse would give _____ 1000 mg tablet(s) three times a day.
9) Lasix 30 mg, IM, is prescribed as a diuretic. Lasix was available as 40 mg/mL. The nurse would give ______mL.
10) Scopolamine 0.3 mg was ordered subcutaneously as a preanesthetic medication. The medication was available in ampules containing grains 1/200 per mL. The nurse would give _____mL.
11) The physician prescribed 25 mg of Librium, IM. Add 2 mL of diluent to yield 100 mg/2ML. The nurse should give _____ mL.
12) The physician prescribed 5 mg of Garamycin for a child. The medication is available as 20 mgs/mL. To give 5 mg, you would give ____ mL.
PRACTICE, PRACTICE, PRACTICEAnd HOLLER if you need help!