McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Math for the Pharmacy Technician: Concepts and Calculations Chapter 10: Pediatric and Geriatric Considerations Egler Booth

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  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. When you have successfully completed Chapter 10, you will have mastered skills to be able to:

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 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 Distribution  Process that moves the drug from the bloodstream to other body tissues and fluids  Target site is where the drug product produces its desired effect  Each drug affects drug target sites

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Biotransformation  Process that chemically changes the drug in the body  Occurs primarily in the liver  Helps to protect the body from foreign chemicals including drugs

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Elimination  Process where the drug leaves the body  Main way of eliminating is in the urine  Other ways Air that we exhale Sweat Feces Breast milk Other body secretions

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Drug Adjustment  Adjustment is needed if one of these four processes are not functioning within certain limits.  Dose adjustment is made according to nature and severity of patient’s condition.  You are not expected to make these adjustments, but be aware that they may have to be done.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Conditions That Impact Dosing Functions of body systems change over the life of a person Newborns – systems not developed yet  pH of stomach is lower  Thinner skin  Liver still developing  Less circulation to muscles

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Conditions That Impact Dosing (con’t) Geriatrics – systems begin to deteriorate Skin and veins become fragile Decreased liver function Decreased kidney function Poor circulation

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Working with Special Populations  Other Considerations Parent or caretaker may be administering or assisting them with medications These individuals will need education regarding any regular or special requirements

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Teaching Patients or Caretaker About Medications 1. Name of the medication 2. Purpose 3. How to store it 4. How long patient needs to take the medication 5. How and when to take it 6. How to know if it is effective

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Teaching Patients or Caretaker About Medications (con’t) 7. Required follow-up tests, doctor appointments 8. Possible side effects and what to do 9. Interactions with other drugs and foods 10. Symptoms to report to the doctor 11. What to do if a dose is missed 12. Keeping a list of all medications

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Ensuring Safe Dosages  When you are working with special populations, always check the package insert, drug label, or product literature to ensure the safety of the dose to be administered.  Drug orders may be written in several ways. If you measure the medication, you have the responsibility to check whether the dose is the standard recommended dose.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Ensuring Safe Dosages (cont.)  The recommended dose is sometimes written as a range, with a minimum and a maximum recommended dose. In this case, you will need to determine if the dose ordered is not less than the minimum or greater than the maximum recommended dose.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Ensuring Safe Dosages (con’t) Determine whether the following order is safe. If safe, calculate the amount to administer. Patient: Child who weighs 14.5 kg Ordered: Amoxil 75 mg PO q8h On hand: Usual child dose mg/kg day q8h Answer: Dosage doesn’t fall within recommended dosage range; contact the physician.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved CAUTION ! Convert ounces carefully.  The weight of babies is often measured in pounds and ounces.  Because 16 oz = 1 lb, an ounce is not a tenth of a pound.  A baby who weighs 8 lb 6 oz does not weigh 8.6 lb.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved CAUTION! (con’t) Convert 6 ounces to pounds using as the conversion Thus, 8 lb 6 oz = lb

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Dosages Based on Body Weight Calculating dosage based on body weight: 1.Convert the patient’s weight to kilograms 2.Calculate the desired dose, D, by multiplying dose ordered by the weight in kilograms such as

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Dosages Based on Body Weight (con’t) 3.Confirm whether or not the desired dose is safe by checking the label, package insert, or product literature. If unsafe, consult the physician who wrote the order 4.Calculate the amount to administer, using fraction proportion, ratio proportion, dimensional analysis, or the formula method

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Dosages Based on Body Weight (con’t) Calculate the amount to administer to a three- year-old who weighs 34 lb. Ordered: hysocyamine sulfate 5 mcg/kg subq 1 h pre-anesthesia On hand: hysocyamine sulfate 0.5 mg/mL Answer: 0.15 mL

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Pediatric Specific Dosage Calculations  There are two 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 age of the child to determine the desired dose.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Pediatric Specific Dosage Calculations (con’t)  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 ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Pediatric Specific Dosage Calculations (con’t)  Clark’s Rule for children’s dosage calculations uses the following formula:

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Pediatric Specific Dosage Calculations (con’t) Using Clark’s Rule, find the amount to be dispensed. The patient is a 6-year- old child who weighs 50 lb; the average adult dose is 250 mg.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 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 1 year of age):

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Pediatric Specific Dosage Calculations (con’t) Using Young’s Rule, find the amount to be dispensed. The patient is a 6-year- old child who weighs 50 lb; the average adult dose is 250 mg.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 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  A patient’s BSA is stated in square meters or m 2  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 To determine a patient’s Body Surface Area (BSA): 1. If you know the height in cm and weight in kg, calculate

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Calculating BSA Using a Formula (con’t) 2. If you know the height in inches and weight in pounds, calculate

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 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 m 2

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 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) Find the body surface for a baby who is 24 in and weighs 14 lb and 8 oz Use the “Child’s Nomogram” BSA = 0.21 m 2

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Calculating Dosage Based on BSA Calculating dosage based on BSA: 1. Calculate the patient’s BSA. 2. Calculate the desired dose: dosage ordered x BSA = desired dose 3. Confirm whether or not the desired dose is safe. If unsafe, consult the physician who wrote the order. 4. 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 Calculating Dosage Based on BSA (con’t) Ordered: Ceenu (1 st 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/m 2 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 Review and Practice True or False A baby who weighs 6 lb 8 oz weighs 6.8 lb. Answer: False

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Review and Practice Answer: True True or False A baby who weighs 9.5 lb weighs 9 lb 8 oz.

McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 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 Pediatric and Geriatric Calculations THE END No matter how rushed you may feel, you cannot take shortcuts with any medication calculations, especially patients from special populations.