2. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved Math for the Pharmacy Technician: Concepts and Calculations Chapter 7: Oral Medications and Parenteral Dosages Egler Booth

3. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-2 Oral Medications and Parenteral Dosages

4. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-3 Learning Objectives  Distinguish between different types of oral medications.  Recognize the types of solid oral medications that may not be altered by crushing or opening them.  Calculate the amount of a parenteral medication to administer. When you have successfully completed Chapter 7, you will have mastered skills to be able to:

5. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-4 Learning Objectives (con’t)  Select the appropriate syringe.  Correctly reconstitute powdered medications.  Calculate the amount of reconstituted medications to administer.  Accurately calculate doses of inhalant, rectal, and transdermal medications.  Identify errors that occur in calculating and preparing parenteral doses.  Calculate estimated days supply.

6. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-5 Introduction  You will learn to apply the simple calculation methods learned in Chapter 6 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.

7. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-6 Tablets and Capsules Solid oral medications come in several forms: Tablets Caplets Capsules

8. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-7 Tablets Most common form of solid oral medications  Combines with inactive ingredients  Forms a solid disk or cylinder  to be swallowed  sublingual  buccal  chewable  dissolve in water

9. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-8 Caplets  Oval-shaped  Special coating -- easier to swallow Caplet

10. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-9 Capsules  Oval-shaped gelatin shells  Contain medication in powder or granule form  The shell is usually two pieces that fit together  The shell can be separated to remove the medication when the patient cannot swallow a pill

11. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-10 Gelcaps  Usually a liquid medication in a gelatin shell  Not designed to be opened

12. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-11 Scored Tablets  Scoring 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

13. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-12 Calculating Dosages for Tablets and Capsules  Always question and/or verify when your calculation indicates to give a portion of a tablet when the tablet is not scored.  Question and recheck any calculation that indicates that you should dispense more than three tablets or capsules.

14. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-13 Calculating Dosages for Tablets and Capsules (con’t) Follow these steps when determining the amount of medication to be dispensed 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 dispense by the method of your choice.

15. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-14 Calculating Dosages for Tablets and Capsules (con’t) Follow these steps when determining the amount of medication to be dispensed to a patient: Recheck your calculation if necessary. 3. Apply critical thinking skills to determine whether the amount you have calculated is reasonable.

16. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-15 Review and Practice The order is to give the patient 15 mg codeine PO now. You have 30 mg tablets available. Calculate the correct amount of medication to give using one of the following methods. Fraction Proportion Ratio Proportion Dimensional Analysis Formula Method

17. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-16 Fraction Proportion Method Calculating the Amount to Dispense by Fraction Proportion: 1. Set up the proportion as follows: dosage unit amount to dispense dose on hand desired dose 2. Cancel units. 3. Cross multiply, then solve for the unknown value.

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

19. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-18 Dimensional Analysis Method Calculating the Amount to Dispense by Dimensional Analysis: With dimensional analysis you will not need to calculate the desired dose and amount to dispense separately. You will place your unknown (amount to dispense) 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.

20. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-19 Dimensional Analysis Method (con’t) Calculating the Amount to Dispense by Dimensional Analysis (con’t): 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.

21. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-20 Dimensional Analysis Method (con’t) Calculating the Amount to Dispense by Dimensional Analysis (con’t): 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. 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. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-21 Formula Method Calculating Amount to Dispense 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 dispense

23. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-22 Formula Method (con’t) Calculating Amount to Dispense Using the Formula Method (con’t): 3. Cancel the units. 4. Solve for the unknown.

24. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-23 Review and Practice The order is to give the patient 15 mg codeine PO now. You have 30 mg tablets available. Calculate the correct amount of medication to give using one of the following methods. Fraction Proportion Ratio Proportion Dimensional Analysis Formula Method Answer: ½ tablet

25. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-24 Crushing Tablets or Opening Capsules Uses: Patients who have difficulty swallowing pills Patients who have tube feedings nasogastric tubes gastrostomy tubes jejunostomy tubes May need physician order first Check the policy

26. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-25 Crushing Tablets or Opening Capsules (con’t) Mixing Crush certain tablets. Open certain capsules. Mix with soft foods or liquids. Check for interactions between medication and the food or fluid. Example - Tetracycline is inactivated by milk and should not be given with antacids or vitamin and mineral supplements.

27. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-26 Crushing Tablets or Opening Capsules (con’t) Tube feedings Must first dissolve the crushed tablet or opened capsule in a small amount of warm water.  If medication cannot be crushed, see if an alternative form of the medication exists and ask the physician to order it that way.

28. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-27 Some Common Food and Drug Interactions Medication: Mixed with: Causes: AntipsychoticsCoffee and teaReduces effectiveness of drug BronchodilatorsCaffeineStimulates the CNS Central Nervous System (CNS) Depressants Black cohosh, ginseng, kava kava, St. John’s wort, valerian, ETOH Intensifies sedative effects of CNS depressant

29. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-28 Some Common Food and Drug Interactions (con’t) Medication: Mixed with: Causes: ErythromycinAcidic fruits or juices, carbonated beverages Decreases antimicrobial activity Ferrous sulfate TeaDecreased absorption HaloperidolCoffee and teaDecreased absorption

30. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-29Medication: Mixed with: Causes: InsulinCoffeeStimulated excretion Monoamine oxidase inhibitors Foods containing tyramine such as hard cheeses, chocolate, red wine, and beef or chicken liver Headache, nosebleed, chest pain, severe hypertension Some Common Food and Drug Interactions (con’t)

31. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-30 Some Common Food and Drug Interactions (con’t) Medication: Mixed with: Causes: TetracyclinesDairy productsReduces effectiveness of drug

32. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-31 Crushing Tablets or Opening Capsules 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

33. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-32 Enteric-coated Tablets  Have a coating that 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

34. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-33 Enteric-coated Tablets (con’t)  Often look like candies that have a soft center and a hard shell  Must never be crushed, broken, or chewed  Must be swallowed with their coating intact

35. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-34 Sustained-Release Medications  Allows the drug to be released slowly into the bloodstream over a period of several hours.  If the medication is scored, it may be broken at the scored line.  Do not crush or dissolve.  This would allow too much medication to be absorbed at one time.

36. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-35 Spansules  These contain granules of medication with different coatings that delay release of some of the medication.  You may open spansules and gently mix the granules in soft food, but do not crush or dissolve the granules.

37. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-36 Must Not Medications That Must Not Be Crushed or Dissolved  Names that indicate sustained- release medications: -BidLATempule -DurCRChronotab Plateau CapXLRepetab SpanSequel Tembid SASpansule SRExtentab

38. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-37 Must Not Medications That Must Not Be Crushed or Dissolved (con’t)  Names that indicate enteric-coated medications: EC Enseal

39. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-38 Reconstituting Liquid Medications 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 dispensing.

40. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-39 Reconstituting Liquid Medications (con’t) Reconstituting Liquid Medications:  Check the label to determine whether the reconstituted medication must be refrigerated.  Write on the label The date and time you reconstituted the medication. Your initials. Strength of reconstitution.

41. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-40 Reconstituting Liquid Medications (con’t) Reconstituting Liquid Medications:  Check the label to determine how long the reconstituted medication may be stored.  Discard any medication left after this time period has passed.

42. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-41 Reconstituting Liquid Medications (con’t) Reconstituting Liquid Medications:  When medication can be reconstituted in different strengths, select the strength that will allow the desired dose in the smallest volume.

43. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-42 Reconstituting Liquid Medications (con’t) Reconstituting Liquid Medications:  Read the order carefully when calculating the amount to dispense.  The physician usually orders the dose in units of drug, not volume of liquid.  Calculate the volume needed to dispense the desired dose.

44. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-43 Calculating the Volume of Liquid Oral Medication To calculate the volume of liquid oral medication to Dispense, use the same methods that you use for solid oral medications: fraction proportions ratio proportions formula dimensional analysis

45. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-44 Calculating the Volume of Liquid Oral Medication (con’t) Find the amount to Dispense.  Ordered: Ventolin 5 mg PO now  On hand: Ventolin syrup 2 mg per 5 mL Use the calculation method of choice.

46. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-45 Fraction Proportion Method Calculating the Amount to Dispense by Fraction Proportion: 1. Set up the proportion as follows: dosage unit amount to Dispense dose on hand desired dose 2. Cancel units. 3. Cross multiply, then solve for the unknown value.

47. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-46 Ratio Proportion Method Calculating the Amount to Dispense by Ratio Proportion: 1.The proportion will be set up as follows: dosage unit : dose on hand :: amount to Dispense : desired dose Or Q : H :: A : D 2. Cancel units. 3. Multiply the means and extremes then solve for the missing value.

48. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-47 Dimensional Analysis Method Calculating the Amount to Dispense by Dimensional Analysis: With dimensional analysis you will not need to calculate the desired dose and amount to dispense separately. You will place your unknown (amount to dispense) 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.

49. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-48 Dimensional Analysis Method Calculating the Amount to Dispense by Dimensional Analysis (con’t): 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.

50. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-49 Dimensional Analysis Method Calculating the Amount to Dispense by Dimensional Analysis (con’t): 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.

51. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-50 Formula Method Calculating Amount to Dispense 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 dispense

52. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-51 Formula Method (con’t) Calculating Amount to Dispense Using the Formula Method (con’t): 3. Cancel the units. 4. Solve for the unknown.

53. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-52 Patient Education: Liquid Medications  Read the label to learn how to store the medication.  Use the measuring device provided or a device purchased specifically to measure medications.  Household teaspoons and tablespoons do not measure liquid accurately.

54. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-53 Patient Education: Liquid Medications (con’t)  Do not store medication longer than the label indicates.  Medication used after expiration date may have lost potency or its chemical composition may have changed.

55. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-54 Patient Education: Liquid Medications (con’t)  Wash the measuring device with hot water and a dishwashing detergent after each use.  Dry it thoroughly.  Store it in a clean container such as a plastic sandwich bag.  Keep liquid medication in its original container.  Do not transfer it to other containers.

56. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-55 Parenteral Dosages  Parenteral route of administration; medications that are delivered outside of the digestive tract; most often refers to injections. The most common injection types used to deliver medications include: Intramuscular (IM)-Medication administered into a muscle by injection. Subcutaneous (Sub-Q)-Medication administered under the skin by injection. Intravenous (IV)-Medication delivered directly to the bloodstream through a vein. Intradermal (ID)-Medication administered between the layers of skin.

57. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-56 Parenteral Dosages (cont.)  Injections are mixtures that contain the drug dissolved in an appropriate liquid.  The dosage or solution strength on an injectable medication’s label indicates the amount of drug contained within a volume of solution.  Dosage strength may be expressed in milligrams per milliliter, as a percent, or as a ratio.  Once you have determined the amount to be administered to the patient, you must select the appropriate syringe.

58. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-57 Parenteral Dosages (con’t)  Selecting a syringe 1. If the amount of injection to administer is 1 mL or more, use a standard 3-mL syringe. 2. If the amount of injection to administer is less than 1 mL but greater than or equal to 0.5 mL, use a 1-mL tuberculin syringe. 3. If the amount of injection to administer is less than 0.5 mL, use a 0.5-mL tuberculin syringe.

59. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-58 Other Medication Routes  Medications may be given by a variety of routes besides oral and common parenteral routes. These routes are used for:  inhalants  ophthalmic and otic drops  topical and transdermal  rectal and vaginal medications.

60. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-59 Other Medication Routes (con’t)  Inhalant-medication administered directly to the lungs, usually through a metered-dose inhaler or nebulizer.  Topical-medications are applied to the skin and include ointments, creams, and lotions.  Transdermal-medications are administered through the skin, typically via a patch.

61. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-60 Other Medication Routes (con’t)  Ophthalmic medications are used for the eyes and  Otic medications are used for ears. Both are usually given in liquid/drop form. Some ophthalmic medications are supplied in ointment form.

62. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-61 Other Medication Routes (con’t)  Rectal-medication administered through the rectum, usually a suppository.  Vaginal-medication administered through the vagina, in suppository, cream or tablet form.

63. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-62 Estimated Days Supply  As a pharmacy technician you may need to determine the estimated days supply of a prescription, which is how long the medication will last the patient if taken correctly.

64. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-63 Estimated Days Supply (cont.)  To determine estimated days supply you will multiply amount of medication to dispense by days needed over the number of dosage units per day. Amount to dispense 

65. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-64 Review and Practice True or False  Any tablet can be broken in half to give to a patient. Answer: False

66. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-65 Review and Practice True or False  Enteric-coated tablets can be crushed to give to a patient. Answer: False

67. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-66 Review and Practice  Which of the following foods are contraindicated to mix with tetracyclines? A. Water B. Orange juice C. Milk D. Applesauce Answer: C. Milk

68. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-67 Review and Practice  Which of the following types of medications can be crushed for administration? A. Scored tablets B. Enteric-coated tablets C. Sustained-release tablets D. Sublingual tablets Answer: A. Scored tablets

69. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-68 Review and Practice  What preparation must be done before Dispensing 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. Answer: C. Mix with warm water.

70. McGraw-Hill ©2010 by the McGraw-Hill Companies, Inc All Rights Reserved 7-69 Oral Medications and Parenteral Dosages THE END Remember that excellence is a must with dosage calculations.