Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Chapter 4 Conversions and Calculations Used by Pharmacy Technicians

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. 1.Describe the history of International System of Units. 2.Convert Arabic numbers into Roman numerals. 3.Convert traditional time into military time. Conversions Lesson 4.1

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3.Use mathematical calculations to determine dosage using: multiplication/division, fractions, decimals, percentages, ratios. 4.Demonstrate the ability to convert between the various systems of measurement used in the practice of pharmacy: metric system, common household measurements, apothecary system, and avoirdupois system. Conversions (cont’d) Lesson 4.1

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6.Calculate pediatric and geriatric dosages. 7.Calculate drip rates. Calculation in Practice Lesson 4.2

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8.Understand the process of dilution. 9.Understand alligation. Calculation in Practice (cont’d) Lesson 4.2

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved.Introduction  The ability to ___________conversions is a required competency of pharmacy technicians.  It is a _____________for filling orders and calculating dosages in the pharmacy.  All transcribing calculations need to be ________________by a pharmacist.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Pharmacy  Pharmacy measurements come from different regions of the world.  The United States Pharmacopeia (USP) recognizes the ____system as the official system of measurement for pharmacy.  Household, apothecary or avoirdupois units may also be used.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Pharmacy (cont’d)  A good way to become familiar with common pharmacy measurements is to start with what you know and then slowly build on that knowledge.  The pharmacy technician must translate the _____________orders into lay terms.  You must make the instructions easy enough for a child to understand.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Rules for Determining Roman Numerals  When a numeral is_________, its value is repeated.  A numeral may not be repeated more than _____ times.  V, L, and D are never repeated.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Rules for Determining Roman Numerals (cont’d)  When a smaller numeral is placed before a larger numeral, it is _____________ from the larger numeral  When a smaller numeral is placed after a larger numeral, it is ______________ to the larger numeral  V, L, and D are never subtracted.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Rules for Determining Roman Numerals (cont’d)  Never subtract more than ____numeral  When subtracting, only use a numeral before the next two higher-value numerals

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. International Time  International (military) time used exclusively in hospital settings.  Orders are written 24 hours a day to ensure that all medical-related caretakers understand exactly when the order was -- ___________________and when the medication or treatment is to take place.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. International Time (cont’d)  The system is based on 100.  Starting with the first hour of the day, the clock begins at _____ (1 AM) through 2400 or 12 midnight.  By using this system there is never any question as to when an order was written or which order supersedes another.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Military Time Clock

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Multiplication/Division  Multiplication is used to enlarge or ______________ a recipe.  Division is used to determine a part or portion of a recipe.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Converting Fractions to Decimals  To convert a proper or improper fraction to a decimal, divide the _____________ by the denominator.  To convert a mixed fraction to decimal, convert into improper fraction, then divide the numerator by the denominator.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Converting Fractions to Percentages  Divide the numerator by the denominator.  When rounding a number, determine to what ______________ number or decimal place the number is to be rounded.  1/3 = …

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Converting Ratios to Percentages  A ratio ______________ two quantities or measurements.  1:2 is a ratio and is read “____is to ___.”  Ratios can also be written as fractions.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Converting Decimals to Percentages  Percentages are used:  To identify the ______________ or concentration of a medication  In performing dilution problems  In _______________the markup on prices, payment discounts, net profits, and gross profits

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Converting Decimals to Percentages (cont’d)  To convert a fraction to a percent, divide the numerator by the denominator and ____________ by 100.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Ratios/Proportions  _______________: a relationship between two parts of a whole or between one part and the whole  Proportion: a relationship between ____________ ratios

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Working with Word Problems  Ask yourself what is known and what is being ______________.  Unnecessary information can be ignored.  Some problems might require several steps.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Metric System  Metric system used throughout pharmacy because of its accuracy.  Metric units include:  Milliliters, cubic centimeters, and liters for volume  Kilograms, grams, milligrams, and micrograms for weight  Millimeters and meters for distance

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Metric System (cont’d)  There is a _______________ -unit difference between each measurement Most Common Metric Measurements kg______g________mg________mcg 1000x1000x1000x

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Metric System (cont’d)  The use of millimeters is reserved for drug calculations based on __________surface areas.  Knowing the basics for volume and weight conversions is adequate.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Household Measurements  The most common measurement system still used in the United States is the household system.  Measurements come in a variety of units.  Volume refers to_______________.  Weight refers to _________ingredients.  Length refers to distance.  Most common measurement is the ________spoon

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Common Household Measurements Household MeasurementsMetric (Volume)(Volume) Household 1 teaspoon5 ml or cc*1 teaspoon 1 tablespoon15 ml or cc3 teaspoons 1 cup240 ml or cc8 ounces 1 pint480 ml or cc2 cups 1 quart960 ml or cc4 cups 1 gallon3840 ml or cc16 cups or 3.84 L *Remember that 1 ml and 1 cc contain the same amount of liquid.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Apothecary System  _________ System originated in Europe.  Units used in this system are grains and scruples for dry weight.  Drams and minims used for liquids  More common measurements include ounces and pounds.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Apothecary Weights Dry WeightFluid Weight 1 grain = 60 mg1 dram= grains= 1 gram8 drams= grains= Э 13 scruples*= 1 1 dram = Э 3 1 ounce = 8 or = Э 24 = gr 480 = 31.1 grams 1 pound= 16 ounces = 96 =Э 288 = gr 5760 = 454 grams *Scruples and minims are not commonly used units

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Conversion Table: Apothecary/Metric/Househol d Apothecary Apothecary MetricMetricCommon VolumeWeightVolumeWeight Household 1130 ml30 g2 tbsp 4415 ml15 g1 tbsp ml 7.5 g½ tbsp 1gr 60 4 ml 4 g1 tsp ½gr 30 2 ml 2 g½ tsp

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Avoirdupois System  Originated in __________  Similar to the apothecary system because it also uses grains, ounces, and pounds for weight  For avoirdupois and metric equivalents, refer to Table 4-5

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Important Differences Among Systems  The metric system is used for _______________ drugs.  There are differences among manufacturer’s products and their weights.  Conversions with these variances are approximate.  A pint can be 473 ml, 480 ml, or 500 ml.  1 pound = _____ g in metric, but only 373 g in the apothecary system.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Oral Syringes and Injections  Syringes may need to be provided with liquid medications.  The syringe should never contain more than _______ times the volume of medication to be administered.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Pediatric and Geriatric Dosing  When the strength of the medication needed cannot be measured with a teaspoon or is an odd amount, ___________ must be used.  The pharmacist, not the technician, should show the parent or guardian of the patient how to measure the correct amount.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Pediatric and Geriatric Dosing (cont’d)  Senior citizens may find that devices with large bold calibrations may help them ________ the correct amount better.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Calculating the Proper Dose  Because all manufacturers provide proper dosing regimens based on kilograms, it is necessary to convert pounds into kilograms.  There are _______ pounds per kilogram.  16 ounces = 1 lb2.2 pounds = 1 kg  To determine how many kg in 1 lb, divide.  To determine how many lbs in 1 kg,_____________.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Calculating Body Surface Area (BSA)  BSA results in the most accurate dose because it is based upon both the height and ____________of the patient.  Is extremely important when calculating chemotherapeutic and pediatric doses  Need to know both the patient’s weight (pounds or kilogram) and height (inches or centimeter), and a nomogram

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Other Methods of Calculating Pediatric Doses  Clark’s Rule: uses the patient’s weight as the basis for calculating the dose  Weight of the child in lbs/150 x adult dose = child’s dose  Young’s Rule: uses the patient’s age as the criteria in calculating the dose  Child’s age in years/ (child’s age + 12) x adult dose = child’s dose

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Geriatric Patients  A major consideration in the dosing of elderly patients is kidney function.  Reduced kidney function results in:  Reduced drug elimination  Drug accumulation  Possible toxic drug levels and adverse effects

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Drip Rates  Hospital pharmacy technicians deliver a 24-hour supply of IV solutions to nursing units daily.  Most IV piggybacks are smaller IV solutions that are given over 30 to 60 minutes.  Large volume medications need to be given at a slow rate because the veins can only handle a small volume.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Drip Rates (cont’d)  For large volume__________, pharmacy technicians must be able to calculate the volume needed to last over a certain amount of time, or they might need to calculate how much longer a currently hanging IV solution will last.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Intravenous (IV) Drip System

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Drip Rates (cont’d)  Calculations involve the following:  The right amount of drug that is to be given ____________ time  The amount of time left until an IV runs out  The amount of drug needed to last a certain amount of time

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Drip Rates (cont’d)  Basic conversions are as follows:  Time:1 hour = 60 minutes 24 hours = 1 day  Volume: _____mL = 60 gtt

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Drip Rates (cont’d)  Steps involved in determining drops per minute:  What is the __________ factor?  What will be the milliliters per hour?  What will be the milliliters per minute?  What will be the _________ per minute?

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Dilution  Pharmacy may receive a prescription for a liquid or _______medication that is not available commercially in the strength prescribed by the physician.  Must dilute the commercially available product to a lower strength.  Diluted through the addition of a diluent or ___________ to the desired strength.

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Dilution (cont’d)  The concentration or _____________of a substance can be expressed in three different ways:  Percent  Ratio strength  Fractions

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved. Dilution (cont’d)  The amount of diluent needed can be calculated by using the following equation:  Final Weight (FW) or Final _________(FV) - Initial Weight (IW) or Initial Volume (IV) = Amount of diluent

Copyright © 2013 by Saunders, an imprint of Elsevier Inc. All rights reserved.Alligation  Alligation is used when you need to prepare (_____________) percent strength that you do not have in stock.  Use two other strengths to attain the correct one.  Any two strengths can be used as long as only one is less concentrated than the final solution.