Chapter 10, Pediatric and geriatric considerations. This chapter includes drug.orders based upon body weight. It introduces body surface area (BSA).calculations. Discussions of special concerns for pediatric and geriatric.patients are also presented.
Math for the Pharmacy Technician: Concepts and Calculations Egler • Booth Chapter 10: Pediatric and Geriatric Considerations McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Pediatric and Geriatric Considerations McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-3 Learning Objectives When you have successfully completed Chapter 10, you will have mastered skills to be able to: Explain why dosages calculations for specific populations must be based on the individual patient Identify factors that affect the absorption, distribution, biotransformation, and elimination of drugs in special populations Determine safe doses for special population patients McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-4 Learning Objectives (con’t) Determine safe doses for special populations Calculate patient dosages based on body weight Calculate pediatric dosages using Clark’s Rule Calculate pediatric dosages using Young’s Rule McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-5 Learning Objectives (con’t) Find a patient’s body surface area (BSA) Calculate patient dosages based on a patient’s BSA McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-6 Introduction Two special populations require extra consideration when calculating medication dosages Pediatric (children under age 18) Geriatric (mature adults over age 65) Risk of harm is far greater due to way they break down and absorb medications McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-7 Introduction (con’t) Clarify all confusing drug orders Calculate with absolute accuracy Verify that dose is safe Seek assistance from your supervisor Do not take short cuts with medication calculations McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-8 Factors that Impact Dosing Normal dose of medication makes assumptions About the patient’s body and age That body systems are fully developed and functioning Special populations may need dosages adjusted due to this assumption not being true McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-9 Pharmacokinetics Study of how drugs are used by the body Absorption Distribution Biotransformation Elimination Understanding these processes allows for adjustments for special populations McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-10 Absorption Process that moves a drug from the site where it is given into the bloodstream IV medications bypass the absorption process by going directly into the bloodstream Oral medications absorbed in digestive system Topical absorbed through the skin McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-32 Pediatric Specific Dosage Calculations (con’t) Young’s Rule for children’s dosage calculations uses the following formula (this formula can be used only if the child is a least year of age): child' s age in years child' s age in years + 12 years McGraw-Hill × average adult dose = pediatric patient' s dose ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Pediatric Specific Dosage Calculations (con’t) 10-33 Using Young’s Rule, find the amount to be dispensed The patient is a 6-yearold child who weighs 50 lb; the average adult dose is 250 mg years × 250mg = 83.3 mg years + 12 years McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-34 Dosages Based on Body Surface Area (BSA) BSA calculations are used to provide more accurate dosage calculations specific to the patient’s size and severity of his/her illness Some medications are based on patient’s body weight only Both weight and height are used to determine a patient’s body surface McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Calculating BSA Using a Formula 10-35 A patient’s BSA is stated in square meters or m2 To calculate the BSA you must know the height and weight Use a formula or a special chart called a nomogram McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Calculating BSA Using a Formula 10-36 To determine a patient’s Body Surface Area (BSA): If you know the height in cm and weight in kg, calculate height (cm) × weight (kg) BSA = m2 3600 McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-37 Calculating BSA Using a Formula (con’t) If you know the height in inches and weight in pounds, calculate height (in) × weight (lb) BSA = m2 3131 McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-38 Review and Practice Calculating BSA Using a Formula (con’t) Find the body surface area for an adult who is 5’6” tall and who weighs 168 lb BSA = 1.9 m2 McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-39 Calculating the Body Surface Area (BSA) using a Nomogram Using a straight edge, align the straight edge so it intersects at the height and weight Doing so will create an intersection in the BSA scale McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Calculating the BSA using a Nomogram (con’t) 10-40 Find the body surface for a baby who is 24 in and weighs 14 lb and oz Use the “Child’s Nomogram” BSA = 0.21 m2 McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-41 Calculating Dosage Based on BSA Calculating dosage based on BSA: Calculate the patient’s BSA Calculate the desired dose: dosage ordered x BSA = desired dose Confirm whether or not the desired dose is safe If unsafe, consult the physician who wrote the order Calculate the amount to administer, using fraction proportions, ratio proportions, or the formula method McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice 10-42 Calculating Dosage Based on BSA (con’t) Ordered: Ceenu (1st dose) 140 mg now for a child whose height is 38 in and weight is 47 lb According to the package the first dose is a single oral dose providing 130 mg/m2 The dose ordered 140 mg is above the first recommended dose Contact the physician McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-43 Review and Practice True or False A baby who weighs lb oz weighs 6.8 lb Answer: False McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-44 Review and Practice True or False A baby who weighs 9.5 lb weighs lb oz Answer: True McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-45 Review and Practice What two things are pediatric dosages often based on? Answer: Weight and BSA McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 10-46 Pediatric and Geriatric Calculations No matter how rushed you may feel, you cannot take shortcuts with any medication calculations, especially patients from special populations THE END McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved ... have the responsibility to check whether the dose is the standard recommended dose McGraw-Hill ©2 010 by the McGraw-Hill Companies, Inc All Rights Reserved 10- 21 Ensuring Safe Dosages (cont.) The. .. other forms of calculations used to calculate pediatric doses, Clark’s Rule and Young’s Rule Clark’s Rule uses the weight of the child to determine the desired dose and Young’s Rule uses the. .. Memory Tip Young = age; the word “young” refers to the age of an individual, and Young’s Rule uses the age of the child to determine the desired dose McGraw-Hill ©2 010 by the McGraw-Hill Companies,