 # Conversions and calculations used by Pharmacy Technicians

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Conversions and calculations used by Pharmacy Technicians
Pharmacy Tech Practicum

Vocabulary Alligation Apothecary System Diluent Dilution
Household System International Time Metric System Solvent Volume Drip Rates Suspension Piggyback Compounding Solution

Math for Pharmacists/Technicians?
Wide variety of math skills needed to work in Health Care Pharmacy Technicians may use math for a variety of reasons Working the cash register Compounding (mixing) drugs Calculating Drip Rates Calculating Dosage amounts

Roman Numerals Numeric System of Ancient Rome
May be used by physicians when ordering medications Not commonly used for larger numbers in Pharmacy

Roman Numerals There are four basic principles for reading and writing Roman numerals: 1. A letter repeats its value that many times (XXX = 30, CC = 200, etc.). A letter can only be repeated three times. 2. If one or more letters are placed after another letter of greater value, add that amount. VI = 6 (5 + 1 = 6)LXX = 70 ( = 70)MCC = 1200 ( = 1200)

Roman Numerals 3. If a letter is placed before another letter of greater value, subtract that amount. IV = 4 (5 – 1 = 4)XC = 90 (100 – 10 = 90)CM = 900 (1000 – 100 = 900) 4. A bar placed on top of a letter or string of letters increases the numeral's value by 1,000 times.XV = 15, = 15,000 Complete Exercise 4-1 pg

International/Military Time
Military time used exclusively in Hospitals Orders are written 24 hours per day Health care workers must understand exactly when order was written and when treatment should take place Military time decreases confusion

Military Time Conversion Chart
Exercise 4-2 pg 111

Practice Quiz #1 Pg 112

Fractions to decimals and %
Proper- 5/12 Improper- 7/3 Mixed Number 3 ½ Fraction to decimal- Divide Numerator (top number) by the denominator (bottom number) 5/12= 5 divided by 12 Mixed Numbers must be changed to a fraction first Denominator x Whole Number + Numerator 3 ½ = 2 x 3 + 1= 7/2 then 7 divided by 2

Fractions to decimals to %
Decimals to Percent .73 x 100 = 73% or Move the decimal over two spaces top the right Percent to decimal 73% / 100 or =.73 or Move the decimal two spaces to the left

Ratios to % 1 : 2 = ½ Divide the numerator by the denominator x 100

Ratios Ratio- A relationship between two parts of a whole or between one part and a whole. Can be written as ½ or 1:2 Used for compounding in the pharmacy Example 1- one gram of drug in a 1000 ml solution would read as 1:1000 Example grams of a drug in 100ml of solution would read as 25:100 which can be reduced to ¼

Proportions A proportion is a relationship between two ratios
May be written as 1/2 = 2/4 or 1:2 :: 2:4 Proportion problems may be solved by either cross multiplying and dividing or by “means and extremes”

Proportions Example # 1 The pharmacy receives an order for erythromycin suspension 125 mg to be taken TID for 10 D How many ml do you need to fill this order? You have 200mg/5ml You need 125 mg to be taken TID for 10 days Set up equation Have=Need 200mg/5ml=125mg/x 5 x125 = 625/200=3.125ml per dose 3 x ml per day 10 (days) x = ml

Proportions Example #2 You receive an order for Decadron 3mg BID for 30D How many TAB do you need to fill this order? Have=Need 1.5mg TAB =3 mg/x TAB 1 TAB x 3mg = 3/1.5 = 2 TAB 2 Tab/dose x 2 doses per day = 4 tablets per day 4x30=120 Tab total

Proportions Quick Check 4-6 page 117

Proportions Example #3 Prepare 240 mg of gentramicin IVPB (intraveneous Piggyback) using the pharmacy stock concentration of 40 mg/ml bid Need to determine how many ml of the stock solution are needed to fill the 240 mg order 240mg/1 ml = 40 mg/x ml Divide both sides by 40 6ml=x Answer you will need 12 ml of solution to equal 240 mg of drug for dose given twice daily

Word Problems Read through pg 119 Example 4-8

Proportions Exercise 4-7 quick check pg 120 Practice quiz pg 121

Metric System International System of Units
Used to measure weight, distance and volume. Table 4-3 metric prefixes Exercise 4-8 quick check pg 122

Household Measurements
System of measure used in the US Cups, tablespoons and teaspoons are common measurements Examples 4-10, 4-11, 4-12 on page 123 Exercise 4-9 quick check pg 123

Apothecary System Traditional system of pharmacy, originated in Europe
Not common in pharmacies today Dry weight measurements- grain (gr), scruple, dram, ounce and pound. Volume- fluid ounce, dram and minim. Example 4-13 and 4-14 Exercise 4-10 Quick Check Exercise 4-11 Quick Check

Avoirdupois System Originated in Europe Common system of commerce
Items purchased and sold by the ounce and pound Dry weights- pounds, ounces and grains Liquid volume- Fluid ounces (fl oz), pints (pt) and gallons (gal) Exercise 4-12 quick check

Quiz Practice quiz #3 pg 127

Oral Syringes and Injections

Pediatric Dosing

Geriatric Dosing

Calculating Drip Rates

Dilution

Alligation