Pharmacy Calculations Review

1 This module is accredited for contact hours of continuing Pharmacy education and is recognized by the Pharmacy Technician Certification Board (PTCB). LEARNING OBJECTIVESUpon completion of this module, the subscriber will be able to:1. Compute Pharmacy problems by using ratio and proportion or dimensional Compare and convert units among the Pharmacy math systems, especially the metric Calculate quantity and day Calculate doses based on weight and body surface Calculate intravenous (IV) flow Reduce and enlarge compounding : Pharmacy Tech Topics Modules are accredited for Continuing Pharmacy Education (CPE) credits by the Illinois Council of Health-System Pharmacists. The Illinois Council of Health-System Pharmacists is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing Pharmacy education.

2 2011 Illinois Council of Health-System Pharmacists. Pharmacy Tech Topics is a trademark of the Illinois Council of Health-System Pharmacists. The intended audience is Pharmacy module will provide contact hours of continuing Pharmacy education credit for Pharmacy Universal Activity Number: 121-000-11-003-H04-T Type of Activity: KnowledgeValidation Dates: 07/01/11 to 07/31/13 Pharmacy Tech Topics Volume 16 Number 3 July 2011 Pharmacy Calculations Review AUTHOR: Yolanda M. Hardy, PharmDEDITOR: Patricia M. Wegner, PharmD, FASHPDESIGN EDITOR: Stephanie LammiPharmacy Tech Topics (USPS No. 014-766) is published quarterly for $50 per year by the Illinois Council of Health-System Pharmacists, 4055 N. Perryville Road, Loves Park, IL 61111-8653.

3 Phone (815) 227-9292. Periodicals Postage Paid at Rockford, IL and additional mailing offices. POSTMASTER: Send address changes to: Pharmacy Tech Topics , c/o ICHP, 4055 N. Perryville Road, Loves Park, IL 61111-8653 Copyright July 2011 All contents 2011 Illinois Council of Health-System Pharmacists unless otherwise noted. All rights reserved. Pharmacy Tech Topics is a trademark of the Illinois Council of Health-System Calculations Review3 Pharmacy TECH TOPICS JULY 2011 FACULTY DISCLOSUREIt is the policy of the Illinois Council of Health-System Pharmacists (ICHP) to insure balance and objectivity in all its individually or jointly presented continuing Pharmacy education programs. All faculty participating in any ICHP continuing Pharmacy education programs are expected to disclose any real or apparent conflict(s) of interest that may have any bearing on the subject matter of the continuing Pharmacy education program.

4 Disclosure pertains to relation-ships with any pharmaceutical companies, biomedical device manufacturers, or other corporations whose products or services are related to the subject matter of the intent of disclosure is not to prevent the use of faculty with a potential conflict of interest from authoring a publi-cation but to let the readers know about the relationship prior to participation in the continuing Pharmacy education activity. It is intended to identify financial interests and affiliations so that, with full disclosure of the facts, the readers may form their own judgments about the content of the learning activity. Dr. Hardy s submission has been peer reviewed with consideration and knowledge of these potential conflicts and it has been found to be balanced and objective. The author has no real or apparent conflict(s) of interest that may have any bearing on the subject matter of this continuing Pharmacy education is an ever-changing science.

5 As new research and clinical experience broaden our knowledge, changes in treat-ment and drug therapy are required. The author and the publisher of this work have checked with sources believed to be reliable in their efforts to provide information that is complete and generally in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical sciences, neither the author nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they are not responsible for any errors or omissions or for the results obtained from use of such information. Readers are encouraged to confirm the information contained herein with other sources.

6 For example and in particular, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this module is accurate and that changes have not been made in the recom-mended dose or in the contraindications for administration. This recommendation is of particular importance in connec-tion with new or infrequently used THE AUTHORY olanda M. Hardy, PharmDAssistant Professor of Pharmacy Practice Chicago State University College of PharmacyChicago, ILDr. Yolanda M. Hardy is an Assistant Professor of Pharmacy Practice at Chicago State University College of Pharmacy . She is also an adjunct professor at South Suburban College, where she teaches Pharmacy Calculations in the Pharmacy technician program.

7 Dr. Hardy holds a Bachelor of Science in Pharmacy degree from the University of Toledo in To-ledo, Ohio (1999). She earned a Doctor of Pharmacy degree at The Ohio State University in Columbus, Ohio (2001). Following this, she completed a Pharmacy Practice Residency in Community Care with The Ohio State University School of Pharmacy and the Columbus Neighborhood Health Centers, Inc. in Columbus, Ohio. She served on the faculty of Northeastern University School of Pharmacy in Boston, Massachusetts from TECH TOPICSTM JULY 20114 IntroductionCorrect Pharmacy Calculations are imperative to the practice of Pharmacy . From the calculation of amounts of components being added to a compounded total parenteral nutrition (TPN) to the drops per minute rate on the label of an intravenous (IV) bag, Pharmacy Calculations can make a difference of life or death.

8 Being a Pharmacy technician requires a variety of skills and abilities and perhaps most important is the ability to carry out important mathematic Calculations . The goal of this module is to provide a basic Review of the many types of Pharmacy Calculations that phar-macy technicians are asked to 1: Basic calculation FoundationRatio and Proportion and Dimensional Analysis1 Ratio and ProportionRatio and proportion Calculations are based on the concept that one component is in pro-portion to another. As a result, many Calculations may be solved by setting the problem up as a ratio. For example: 1 tablet contains 500mg. One tablet contains 500mg is the same as saying 500mg per 1 tablet . Thus, this can be written as:500mg or 1 tab1 tab 500mgUsing proportions we can determine a ratio that is equal to this 1: If 1 tablet contains 500mg, how many milligrams are in 3 tablets?

9 500mg = Xmg1 tab 3 tabSolving for x, we find that there are 1500mg in 3 tablets. Because we used proportions, we know that the ratio of:500mg is equal to 1500mg or 500mg = 1500mg1 tab 3 tab 1 tab 3 tabExample 2: If one teaspoonful (5ml) of a solution contains 15mg of medication, how many milligrams are there in 4 teaspoonsful or 20ml?15mg = Xmg5ml 20ml15mg x 20ml = Xmg x 5ml 15mg x 20ml = Xmg x 5ml 5ml 5ml 300mg = Xmg 5 160mg = XmgSo there are 60mg in 20mls or 4 teaspoons of the ContentsIntroduction Unit 1: Basic calculation Foundation: Ratio and Proportion and Dimensional Analysis Unit 2: Measurement Systems Used in the Practice of PharmacyUnit 3: calculation of Quantity and Day SupplyUnit 4: calculation of Doses Unit 5: IV Flow RatesUnit 6.

10 Reducing and Enlarging FormulasStriving for Accuracy in Pharmacy CalculationsTips to help minimize calcula-tions errors Pharmacy calculation Practice ResourcesPharmacy Calculations Review5 Dimensional AnalysisDimensional Analysis is another method that may be used to calculate quantities of IV additives or strengths of doses. This method is based on cancelling out the units of mea-sure or labels. Example 1: If 1 tablet contains 500mg, how many milligrams are in 3 tablets?Step 1: Find the ratio that is in the problem. In this case, the ratio is:500mg1 tabStep 2: Set up the problem around the ratio so that the units cancel out. The unit that is left (ie. the unit that does not cancel out with the other units) should correspond to the unit needed for the answer to the problem.