Y khoa - Dược - Chapter 10: Pediatric and geriatric considerations

Math for the Pharmacy Technician: Concepts and CalculationsChapter 10: Pediatric and Geriatric ConsiderationsEgler • BoothPediatric and Geriatric ConsiderationsLearning ObjectivesExplain 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:3Learning 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.4Learning Objectives (con’t)Find a patient’s body surface area (BSA).Calculate patient dosages based on a patient’s BSA.5IntroductionTwo special populations require extra consideration when calculating medication dosagesPediatric (children under age 18)Geriatric (mature adults over age 65)Risk of harm is far greater due to way they break down and absorb medications6Introduction (con’t)Clarify all confusing drug ordersCalculate with absolute accuracyVerify that dose is safeSeek assistance from your supervisorDo not take short cuts with medication calculations7Factors that Impact DosingNormal dose of medication makes assumptionsAbout the patient’s body and ageThat body systems are fully developed and functioningSpecial populations may need dosages adjusted due to this assumption not being true8PharmacokineticsStudy of how drugs are used by the bodyAbsorptionDistributionBiotransformationEliminationUnderstanding these processes allows for adjustments for special populations9Absorption Process that moves a drug from the site where it is given into the bloodstreamIV medications bypass the absorption process by going directly into the bloodstreamOral medications absorbed in digestive systemTopical absorbed through the skin10DistributionProcess that moves the drug from the bloodstream to other body tissues and fluidsTarget site is where the drug product produces its desired effectEach drug affects drug target sites11Biotransformation Process that chemically changes the drug in the bodyOccurs primarily in the liverHelps to protect the body from foreign chemicals including drugs12EliminationProcess where the drug leaves the bodyMain way of eliminating is in the urineOther ways Air that we exhaleSweatFecesBreast milkOther body secretions13Drug AdjustmentAdjustment 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.14Conditions That Impact DosingFunctions of body systems change over the life of a personNewborns – systems not developed yetpH of stomach is lowerThinner skinLiver still developingLess circulation to muscles15Conditions That Impact Dosing (con’t)Geriatrics – systems begin to deteriorateSkin and veins become fragileDecreased liver functionDecreased kidney functionPoor circulation16Working with Special PopulationsOther ConsiderationsParent or caretaker may be administering or assisting them with medicationsThese individuals will need education regarding any regular or special requirements17Teaching Patients or Caretaker About MedicationsName of the medicationPurposeHow to store itHow long patient needs to take the medicationHow and when to take it How to know if it is effective18Teaching Patients or Caretaker About Medications (con’t)Required follow-up tests, doctor appointmentsPossible side effects and what to doInteractions with other drugs and foodsSymptoms to report to the doctorWhat to do if a dose is missedKeeping a list of all medications19Ensuring Safe DosagesWhen 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. 20Ensuring 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.21Review and PracticeEnsuring Safe Dosages (con’t)Determine whether the following order is safe. If safe, calculate the amount to administer.Patient: Child who weighs 14.5 kgOrdered: Amoxil 75 mg PO q8hOn hand: Usual child dose 20-40 mg/kg day q8hAnswer: Dosage doesn’t fall within recommended dosage range; contact the physician.22CAUTION !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.23CAUTION! (con’t)Convert 6 ounces to pounds using as the conversionThus, 8 lb 6 oz = 8.375 lb24Dosages Based on Body WeightCalculating dosage based on body weight:Convert the patient’s weight to kilogramsCalculate the desired dose, D, by multiplying dose ordered by the weight in kilograms such as25Dosages Based on Body Weight (con’t)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 orderCalculate the amount to administer, using fraction proportion, ratio proportion, dimensional analysis, or the formula method26Review and PracticeDosages 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-anesthesiaOn hand: hysocyamine sulfate 0.5 mg/mLAnswer: 0.15 mL27Pediatric 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.28Pediatric 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. 29Pediatric Specific Dosage Calculations (con’t)Clark’s Rule for children’s dosage calculations uses the following formula:30Review and PracticePediatric 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.31Pediatric 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):32Review and PracticePediatric 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.33Dosages 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.34Calculating BSA Using a FormulaA patient’s BSA is stated in square meters or m2To calculate the BSA you must know the height and weight Use a formula or a special chart called a nomogram 35Calculating BSA Using a FormulaTo determine a patient’s Body Surface Area (BSA):1. If you know the height in cm and weight in kg, calculate36Calculating BSA Using a Formula (con’t)2. If you know the height in inches and weight in pounds, calculate37Review and PracticeCalculating 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 m238Calculating the Body Surface Area (BSA) using a NomogramUsing a straight edge, align the straight edge so it intersects at the height and weightDoing so will create an intersection in the BSA scale39Review and PracticeCalculating 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 m240Calculating Dosage Based on BSACalculating dosage based on BSA:1. Calculate the patient’s BSA.2. Calculate the desired dose: dosage ordered x BSA = desired dose3. 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.41Review and PracticeCalculating 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 lbAccording to the package the first dose is a single oral dose providing 130 mg/m2The dose ordered 140 mg is above the first recommended dose. Contact the physician.42Review and PracticeTrue or FalseA baby who weighs 6 lb 8 oz weighs 6.8 lb. Answer: False43Review and PracticeAnswer: TrueTrue or FalseA baby who weighs 9.5 lb weighs 9 lb 8 oz.44Review and PracticeWhat two things are pediatric dosages often based on? Answer: Weight and BSA45Pediatric and Geriatric CalculationsTHE ENDNo matter how rushed you may feel, you cannot take shortcuts with any medication calculations, especially patients from special populations. 46