This page intentionally left blank. Pharmaceutical Calculations 13th Edition Pharmaceutical Calculations 13th Edition Howard C. Ansel, PhD Professor and Dean Emeritus College of Pharmacy University of Georgia Athens, Georgia Acquisitions Editor: John Goucher Managing Editor: Matt Hauber Director of Nursing Production: Helen Ewan Senior Managing Editor/Production: Erika Kors Senior Production Editor: Marian Bellus Designer: Holly McLaughlin Manufacturing Coordinator: Margie Orzech Production Services/Compositor: Maryland Composition/ASI 13th Edition Copyright ᭧ 2010 Wolters Kluwer Health ͦ Lippincott Williams & Wilkins. Copyright ᭧ 2006, 2001, 1996, 1991, 1986 by Lippincott Williams & Wilkins. All rights reserved. This book is protected by copyright. No part of this book may be reproduced or transmitted in any form or by any means, including as photocopies or scanned-in or other electronic copies, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotations embodied in critical articles and reviews. Materials appearing in this book prepared by individuals as part of their official duties as U.S. government employees are not covered by the above-mentioned copyright. To request permission, please contact Lippincott Williams & Wilkins at 530 Walnut Street, Philadelphia PA 19106, via email at permissions @ lww.com or via website at lww.com (products and services). This textbook is intended to provide the underpinnings of the methods used in pharmaceutical calculations. The drugs, drug products, formulas, equations, uses, and doses are included in this textbook for the sole purpose of providing examples in the types of calculations described. The information is not intended for use in any practice or clinical application, nor should it be considered or construed as specific for any individual patient nor as a substitute for current drug package inserts. The author, editors, and publisher make no warranty, express or implied, with regard to the contents and use of this publication and are not responsible, as a matter of product liability, negligence, or otherwise, for any injury resulting from any material contained herein. 987654321 Printed in China First Edition, 1945 Library of Congress Cataloging-in-Publication Data Ansel, Howard C., 1933- Pharmaceutical calculations / Howard C. Ansel.—13th ed. p. ; cm. Includes bibliographical references and index. ISBN 978-1-58255-837-0 1. Pharmaceutical arithmetic. I. Title. [DNLM: 1. Drug Dosage Calculations. 2. Dosage Forms. 3. Drug Compounding—methods. 4. Prescriptions, Drug. 5. Weights and Measures. QV 748 A618p 2010] RS57.S86 2010 615′.1401513—dc22 2008045672 Care has been taken to confirm the accuracy of the information presented and to describe generally accepted practices. However, the authors, editors, and publisher are not responsible for errors or omissions or for any consequences from application of the information in this book and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of the publication. Application of this information in a particular situation remains the professional responsibility of the practitioner; the clinical treatments described and recommended may not be considered absolute and universal recommendations. The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with the current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new or frequently employed drug. Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It is the responsibility of the health care provider to ascertain the FDA status of each drug or device planned for use in his or her clinical practice. LWW.COM Preface The thirteenth edition of Pharmaceutical Calculations represents a thorough update of this text- book, which for more than six decades has met the needs of students in this important subject area. One of the most apparent changes in this edition is the inclusion of learning objectives for each chapter. The intent is not only to define the purpose and direct the student’s focus but also to provide a basis for self-assessment following completion. Another important addition, appearing in the Introduction, presents a step-wise approach in solving calculations problems that should prove beneficial to students toward understanding and building confidence. Throughout its history, one of the distinguishing characteristics of this textbook has been the inclusion of relevant background information to explain the pharmaceutical and/or clinical purpose underpinning each type of calculation. This practice has been continued, with new content in such areas as e-prescriptions; medication orders in nursing homes; hospice-care; patient self-administration of analgesia; intravenous infusion rate calculations for the critical care patient; patient conversions to alternative treatment plans; and other new and expanded areas. Another traditional feature of this textbook has been the substantial use of examples and practice problems. New problems have been added to reflect current drugs in use, including products of biotechnology. For the first time, several problems are presented in multiple-choice format to reflect the method of testing used in some academic programs and employed on standardized examinations. Several features that were introduced in the previous edition have been expanded, namely ‘‘Special Considerations,’’ used to point out the specific relevance of a type of calculation to a pharmaceutics or clinical application; ‘‘Calculations Capsules,’’ which present boxed summaries of the principle calculations in a chapter; and, ‘‘Case in Point,’’ which present practical case studies requiring pharmaceutical calculations. The author acknowledges the difficulty in arranging the sequence of chapters to suit the order used within each academic program. However, an attempt has been made to present a logical approach by placing the fundamentals of pharmaceutical calculations in the initial chapters, followed by chapters having a clinical- or patient-care context, then chapters that address formu- lation and compounding calculations, and, finally, chapters described by some reviewers as meeting a ‘‘special interest.’’ The concluding section of review problems contains all of the types of problems presented in the chapters and may be used both for review and for competency assessment. A new set of problems titled ‘‘Physicians’ Medication Orders’’ is introduced. Appendices include the common systems of measurement and intersystem conversion, select graphical methods, and a glossary of pharmaceutical dosage forms and associated routes of administration. v vi PREFACE New Companion Website Pharmaceutical Calculations, 13th edition, includes additional resources for both instructors and students, available on the book’s companion website at http://thePoint.lww.com/Ansel13e. Resources for Students and Instructors • Interactive math calculations Quiz Bank, with more than 400 review problems and detailed solutions. • Searchable Full Text Online See the inside front cover for more details, including the passcode you will need to gain access to the website. Acknowledgments The author gratefully acknowledges the professional contributions to his revision of pharmacy practitioner-educators Warren Beach, Ted Chaffin, Ken Duke, Elaine Lust, and Flynn Warren for lending their expertise and time. Gratitude also is extended to Loyd V. Allen Jr. and Shelly J. Prince for their continued courtesy in allowing liberal use of their work published in the International Journal of Pharmaceutical Compounding and in Pharmaceutical Calculations: The Phar- macist’s Handbook. The author thanks Barabara E. Lacher for the idea of incorporating learning objectives into the textbook and for other instructional materials. The assistance of James T. Stewart in providing access to current information from the United States Pharmacopeia 31 – National Formulary 26 is acknowledged with appreciation. Special tribute is paid to the memory of Mitchell J. Stoklosa who for more than 50 years co- authored and sustained this textbook. He was a scholar, dedicated educator, valued colleague, delightful human being, and treasured friend. Gratitude is expressed to the reviewers for this revision whose experience was drawn upon during the planning process. The author appreciates their thoughtful analysis and constructive comments, which have enhanced this work. Finally, appreciation is extended to the exceptional people at Lippincott Williams & Wilkins for their masterful job in the design, preparation, and production of this revision. Howard C. Ansel Athens, Georgia vii This page intentionally left blank. Contents Preface .................................................... v Introduction ................................................. xv Scope of Pharmaceutical Calculations ........................ xv A Step-Wise Approach Toward Pharmaceutical Calculations