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Math and Dosage Calculations for Health Care Third Edition Booth & Whaley

Math and Dosage Calculations for Health Care Third Edition Booth & Whaley. Chapter 8: Oral Dosages. Learning Outcomes. 8.1 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.

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Math and Dosage Calculations for Health Care Third Edition Booth & Whaley

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  1. Math and Dosage Calculations for Health CareThird EditionBooth & Whaley Chapter 8: Oral Dosages McGraw-Hill

  2. Learning Outcomes 8.1 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.

  3. 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.

  4. 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.

  5. Tablets and Capsules • Solid oral medications come in several forms: • Tablets • Caplets • Capsules • Gelcaps

  6. 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 • Dissolvable • For swallowing

  7. Tablets and Capsules (cont.) • Caplets • Oval-shaped • Special coating – easier to swallow 500 mg Tylenol caplets 500 mg Tylenol caplets 500 mg Tylenol caplets 500 mg Tylenol caplets

  8. 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

  9. Tablets and Capsules (cont.) • Gelcaps • A liquid medicationin a gelatin shell • Not designed to be opened

  10. 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

  11. 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.

  12. 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.

  13. Tablets and Capsules – Calculating Dosages (cont.) 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.

  14. Tablets and Capsules – Calculating Dosages (cont.) Rule 8-3(cont.) 4. Apply critical thinking skills to determine whether the amount you have calculated is reasonable using Rules 8-1 and 8-2. Recheck your calculation if necessary

  15. 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.

  16. Fraction Proportion Method Procedure 7-1: Calculating the Amount to Administer by Fraction Proportion: 1. Set up the proportion as follows: dosage unitamount to administer dose on handdesired dose 2. Cancel units. 3. Cross multiply, then solve for the unknown value.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  21. 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.

  22. 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

  23. Formula Method (cont.) Procedure 7-4 : Calculating Amount to Administer Using the Formula Method: 3. Cancel the units. 4. Solve for the unknown.

  24. 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

  25. Crushing Tablets or Opening Capsules (cont.) • Mixing with food • Prepare tablet or capsule • Mix with soft foods or liquids • Check for interactions before mixing

  26. Some Common Food and Drug Interactions

  27. Some Common Food and Drug Interactions (cont.)

  28. Some Common Food and Drug Interactions (cont.)

  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.

  30. 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 neverbe crushed, broken, or chewed

  31. 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

  32. 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

  33. Crushing Tablets or Opening Capsules (cont.) Rule 8-4To 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

  34. Crushing Tablets or Opening Capsules (cont.) Drugs that must not be crushed / dissolved Indication of sustained-release drugs: -Bid LA Tempule -Dur CR Chronotab Plateau Cap XL Repetab Span Sequel Tembid SA Spansule SR Extentab

  35. Crushing Tablets or Opening Capsules (cont.) Drugs that must not be crushed / dissolved Indication of enteric-coated drugs: EC Enseal

  36. Liquid Medications • Greater range of dosages possible • Easier to swallow • Children • Elderly • May be less stable • Reconstitution • Refrigeration

  37. Liquid Medications (cont.) 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.

  38. Liquid Medications (cont.) 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

  39. Liquid Medications (cont.) 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.

  40. Liquid Medications(cont.) 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.

  41. Liquid Medications(cont.) To calculate the volume of liquid oral medication to administer use: • Fraction proportion • Ratio proportions • Formula • Dimensional analysis

  42. 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.

  43. Liquid Medications (cont.) Procedure 7-1: Calculating the Amount to Administer by Fraction Proportion: 1. Set up the proportion as follows: dosage unitamount to administer dose on handdesired dose 2. Cancel units. 3. Cross multiply, then solve for the unknown value. =

  44. 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.

  45. 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.

  46. 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.

  47. 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.

  48. 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

  49. Liquid Medications (cont.) Procedure 7-4: Calculating Amount to Administer Using the Formula Method: 3. Cancel the units. 4. Solve for the unknown.

  50. 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.

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