© 2010 The McGraw-Hill Companies, Inc. All rights reserved 8-1 Math and Dosage Calculations for Health Care Third Edition Booth & Whaley Chapter 8: Oral Dosages McGraw-Hill

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Distinguish different types of oral medications. 8.2 Recognize the types of solid oral medications that may not be altered by crushing or opening them. 8.3 List appropriate techniques for administering medication to patients with difficulty swallowing or with feeding tubes. Learning Outcomes

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Learning Outcomes 8.4 Accurately calculate the amount of solid or liquid oral medication to administer to a patient. 8.5 Identify common errors that occur in calculating and preparing dosages for oral administration or via a feeding tube. 8-3

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Introduction You will learn to apply the simple calculation methods learned in Chapter 7 to oral dosages Including solids and liquids Follow the method of calculation that you have chosen by following the color coded examples Remember that excellence is a must with dosage calculations. 8-4

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules Solid oral medications come in several forms: Tablets Caplets Capsules Gelcaps 8-5

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules (cont.) Tablets Most common form of solid oral medications Combination of an amount of drug with inactive ingredients Administration forms Sublingual Buccal Chewable 8-6 Dissolvable For swallowing

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules (cont.) Caplets Oval-shaped Special coating – easier to swallow 8-7 Tylenol caplets 500 mg Tylenol caplets 500 mg

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules (cont.) Capsules Oval-shaped gelatin shells containing medication in powder or granule form The shell is usually two pieces that fit together Can be separated to remove the medication if patient cannot swallow a pill 8-8

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules (cont.) Gelcaps A liquid medication in a gelatin shell Not designed to be opened 8-9

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules (cont.) Scored tablets Allows the tablet to be divided when smaller doses are ordered Most often, scored tablets divide into halves Some divide into thirds or quarters Medication is evenly distributed throughout the tablet 8-10

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules – Calculating Dosages Rule 8-1 Always question and/or verify when your calculation indicates to give a portion of a tablet when the tablet is not scored Never attempt to break a tablet that is not scored.

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules – Calculating Dosages (cont.) Rule 8-2 Question and recheck any calculation that indicates that you should administer more than three tablets or capsules. 8-12

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules – Calculating Dosages (cont.) Rule 8-3 Rule 8-3 Follow these steps when determining the amount of medication to administer to a patient: 1.If necessary, convert the dosage ordered (O) to the desired dose (D) that has the same unit of measurement as the dose on hand (H). 2.Calculate the amount to administer by the method of your choice. 8-13

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Tablets and Capsules – Calculating Dosages (cont.) Rule 8-3 Rule 8-3 (cont.) 4.Apply critical thinking skills to determine whether the amount you have calculated is reasonable using Rules 8-1 and Recheck your calculation if necessary

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Practice The order is to give the patient 15 mg mirtazapine PO now. You have 30 mg scored tablets available. Calculate the correct amount of medication to administer using one of the following methods. 8-15

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Fraction Proportion Method Procedure 7-1: Calculating the Amount to Administer by Fraction Proportion: 1.Set up the proportion as follows: dosage unit amount to administer dose on hand desired dose 2.Cancel units. 3.Cross multiply, then solve for the unknown value. 8-16

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Ratio Proportion Method Procedure 7-2: Calculating the Amount to Administer by Ratio Proportion: 1.The proportion will be set up as follows: dosage unit : dose on hand :: amount to administer : desired dose or Q : H :: A : D 2.Cancel units. 3.Multiply the means and extremes then solve for the missing value. 8-17

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Dimensional Analysis Method Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis: With dimensional analysis you will not need to calculate the desired dose and amount to administer separately. You will place your unknown (amount to administer) on one side of the equation then multiply a series of factors on the right side of the equation. Canceling units will help you determine the equation has been set up correctly. 8-18

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Dimensional Analysis Method (cont.) Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis (cont.): 1.Determine the units of measure for the answer and place it as the unknown on one side of the equation. 2.On the right side of the equation, write a conversion factor with the units of measurement for the desired dose on top and the unit of measurement for the dose on hand. 8-19

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Dimensional Analysis Method (cont.) Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis (cont.): 3.Multiply the conversion factor by a second factor: the dosage unit over the dose on hand. 4.Multiply by a third factor: dose ordered over the number one. 8-20

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Dimensional Analysis Method (cont.) Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis (cont.): 5.Cancel units on the right side of the equation. The remaining unit of measure on the right side of the equation should match the unknown unit of measure on the left side of the equation. 6.Solve the equation. 8-21

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Formula Method Procedure 7-4 : Calculating Amount to Administer Using the Formula Method: 1.Determine the desired dose. Determine the dose on hand (H) and dosage unit (Q) 2.Fill the formula D for the desired dose H for the dose on hand Q for the dosage unit in the formula A for the unknown or the amount to administer 8-22

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Formula Method (cont.) Procedure 7-4 : Calculating Amount to Administer Using the Formula Method: 3.Cancel the units. 4.Solve for the unknown. 8-23

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules Who benefits? Patients who have difficulty swallowing pills Patients who have tube feedings Check the policy May need physician order first 8-24

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) Mixing with food Prepare tablet or capsule Mix with soft foods or liquids Check for interactions before mixing 8-25

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Some Common Food and Drug Interactions DRUGFOODINTERACTION Antipsychotics Coffee and teaReduces effectiveness of drug Bronchodilators CaffeineStimulation of the nervous system CNS depressants Black cohosh, ginseng, kava kava, St. John’s wort, valerian, ETOH Intensified sedative effects drug Erythromycin Acidic fruits, juices; carbonated beverages Decreased antimicrobial activity 8-26

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Some Common Food and Drug Interactions (cont.) 8-27 DRUGFOODINTERACTION Ferrous sulfate TeaDecreased absorption Haloperidol Coffee and tea Decreased absorption Insulin Coffee Stimulated excretion MAO inhibitors Foods with tryamine (hard cheeses, chocolate, red wine, and beef or chicken liver) Headache, nosebleed, chest pain, severe hypertension

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill 8-28 DRUGFOODINTERACTION Tetracyclines Dairy products Reduced effectiveness of the drug Antihystamines, cholesterol lowering agents, calcium channel blockers Grapefruit and grapefruit juice Muscle aches, fatigue, increase side effects Some Common Food and Drug Interactions (cont.)

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill 8-29 Crushing Tablets or Opening Capsules (cont.) Tube feedings Dissolve the crushed tablet or opened capsule in a small amount of warm water. If medication cannot be crushed, check for an alternative form and ask the physician to change the order.

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) Enteric-coated tablets Coating dissolves only in an alkaline environment such as the small intestine Deliver medication that would be destroyed by the stomach acid or that could injure the stomach lining Must never be crushed, broken, or chewed 8-30

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) Sustained-Release Medications Drug is released slowly into the bloodstream If scored, break at scored line Do not crush or dissolve – allows too much medication to be absorbed at one time 8-31

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) Spansules Contain granules of medication with different coatings that delay release of some of the medication Spansules may be opened and the granules gently mixed with soft food Do not crush or dissolve the granules 8-32

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) Rule 8-4 Rule 8-4 To prevent an incorrect dose of medication, do not crush or otherwise alter any of the following: Enteric-coated tablets Sustained-release forms of medication Any tablet with a hard shell or coating Tablets for sublingual or buccal use Capsules with seals that prevent separating the two parts 8-33

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill must not Drugs that must not be crushed / dissolved Indication of sustained-release drugs: -BidLATempule -DurCRChronotab Plateau CapXLRepetab SpanSequelTembid SASpansule SRExtentab 8-34 Crushing Tablets or Opening Capsules (cont.)

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Crushing Tablets or Opening Capsules (cont.) must not Drugs that must not be crushed / dissolved Indication of enteric-coated drugs: EC Enseal 8-35

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications Greater range of dosages possible Easier to swallow Children Elderly May be less stable Reconstitution Refrigeration 8-36

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Rule 8-5 Rule 8-5 Reconstituting Liquid Medications : Use only the liquid specified on the drug label. Use the exact amount of liquid specified on the drug label. Check the label to determine whether the medication should be shaken before administering. 8-37

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Rule 8-5 Rule 8-5 (cont.) Check the label to determine whether the reconstituted medication must be refrigerated. Write on the label Date and time of reconstitution Your initials Strength, if necessary 8-38

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Rule 8-5 Rule 8-5 (cont.) Check the label to determine how long the reconstituted medication may be stored. Discard any medication left after this time period has passed. 8-39

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Rule 8-5 Rule 8-5 (cont.) When medication can be reconstituted in different strengths, select the strength that will allow the desired dose in the smallest volume. Read the order carefully when calculating the amount to administer. Dose is usually ordered in units of drug, not volume of liquid. Calculate the volume needed to administer the desired dose. Liquid Medications (cont.) 8-40

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) To calculate the volume of liquid oral medication to administer use: Fraction proportion Ratio proportions Formula Dimensional analysis 8-41

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Practice Find the amount to administer. Ordered: Ventolin 5 mg PO now On hand: Ventolin syrup 2 mg per 5 mL Use the calculation method of choice. 8-42

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-1: Calculating the Amount to Administer by Fraction Proportion: 1.Set up the proportion as follows: dosage unit amount to administer dose on hand desired dose 2.Cancel units. 3.Cross multiply, then solve for the unknown value =

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-2: Calculating the Amount to Administer by Ratio Proportion: 1.The proportion will be set up as follows: dosage unit : dose on hand :: amount to administer : desired dose or Q : H :: A : D 2.Cancel units. 3.Multiply the means and extremes then solve for the missing value. 8-44

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-3: Calculating the Amount to Administer by Dimensional Analysis: With dimensional analysis you will not need to calculate the desired dose and amount to administer separately. You will place your unknown (amount to administer) on one side of the equation then multiply a series of factors on the right side of the equation. Canceling units will help you determine the equation has been set up correctly. 8-45

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis (cont.) 1.Determine the units of measure for the answer and place it as the unknown on one side of the equation. 2.On the right side of the equation, write a conversion factor with the units of measurement for the desired dose on top and the unit of measurement for the dose on hand. 3.Multiply the conversion factor by a second factor: the dosage unit over the dose on hand. 8-46

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-3 Calculating the Amount to Administer by Dimensional Analysis (cont.): 4.Multiply by a third factor: dose ordered over the number one. 5.Cancel units on the right side of the equation. The remaining unit of measure on the right side of the equation should match the unknown unit of measure on the left side of the equation. 6.Solve the equation. 8-47

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-4: Calculating Amount to Administer Using the Formula Method: 1.Determine the desired dose. Determine the dose on hand (H) and dosage unit (Q) 2.Fill the formula D for the desired dose H for the dose on hand Q for the dosage unit in the formula A for the unknown or the amount to administer 8-48

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Liquid Medications (cont.) Procedure 7-4: Calculating Amount to Administer Using the Formula Method: 3.Cancel the units. 4.Solve for the unknown. 8-49

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Patient Education Read the label to learn how to store the medication. Use the measuring device provided or a device specifically made for measuring medications. Household teaspoons and tablespoons do not always measure liquids accurately. 8-50

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Patient Education (cont.) Do not store medication longer than the label indicates. May lose potency Chemical composition may change 8-51

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Patient Education (cont.) Wash measuring device after each use. Use hot water and dish detergent Dry thoroughly Store in clean container Keep liquid medication in original container. 8-52

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill True or False ___ Any tablet can be broken in half to give a patient the correct dose. ___ Enteric coated tablets can be crushed and given through an NG tube. ____ Some spansules can be pulled apart so the granules can be given with applesauce. Apply Your Knowledge 8-53 T F F Only scored tablets should be broken. Medication could be broken down by stomach acid or it could injure the stomach lining.

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Apply Your Knowledge Which of the following foods are contraindicated to mix with tetracyclines? A.Water B.Orange juice C.Milk D.Applesauce 8-54

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Apply Your Knowledge Which of the following types of medications may be crushed for administration? A.Scored tablets B.Enteric-coated tablets C.Sustained-release tablets D.Spansules 8-55

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill Apply Your Knowledge What preparation must be done before administering a crushed medication through a nasogastric tube? A.Nothing special is needed B.Mix the medication with applesauce C.Mix the medication with warm water D.Mix the medication with ice cream 8-56

© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill End of Chapter If you want to achieve excellence, you can get there today. As of this second, quit doing less- than-excellent work. -- Thomas John Watson, Jr.