DRUG PRESCRIBING FOR THE ELDERLY

1. بسم الله الرحمن الرحيم DRUG PRESCRIBING FOR THE ELDERLY Aly A. Misha’l MD, FACP Senior consultant in Medicine and Endocrinology Amman-Jordan

2. Senility and frailty was described in the Glorious Qur’an in a sense of physical weakness and decline in capabilities, implying significant needs for care, sympathy and mercy.

3. ” .... وقد بلغت من الكبر عتياً“ “…. And I have grown quite decrepit from old age” The Glorious Qur’an, Chapter19: Verse 8

4. ” قال ربي إني وهن العظم مني.....“ “ O my lord! Infirm (Brittle) indeed are my bones …” The Glorious Qur’an, Chapter 19: Verse 4.

5. ” ومنكم من يردُّ إلى أرذل العمل لكي لا يعلم بعد علم شيئاً“ “Some of you are sent back to feeble age, so that they know nothing after what they have known” The Glorious Qur’an, Chapter 16: Verse 70

6. Caring for sick elderly subjects, as part of medical practice, is an act of worship, human and religious duty, that the whole society (Ummah) will be held sinful if it fails to induce and support some of its members to become caring medical professionals (Fardh Kifayah).

7. Optimizing medical care is a cornerstone in both Itqan(perfection) and Ihsan (excellence)

8. Optimizing drug therapy is a cornerstone of proper caring for older individuals.

9. Basic parameters: 1.Deciding whether a drug is indicated. 2.Choosing the most appropriate drug. 3.Determining dose schedules.

10. 4. Monitoring for effectiveness and toxicity. 5. Educating the patient (and family) about expected side effects.

11. 6.Educating the patient (and family) about indications for seeking consultation.

12. 7. Always inquire about the use of over the counter drugs, herbal preparations and dietary supplements.

13. 8. The possibility of an adverse drug event should always be borne in mind when evaluating an elderly individual.

14. Any new symptom should be considered drug-related until proven otherwise.

15. Geriatric Clinical pharmacology: Addresses: • Pharmacokinetics: i.e, absorption, distribution, metabolism and excretion. • Pharmacodynamics: i.e, the physiologic affects of the drug.

16. Adverse drug reactions. • Drug interactions. • Rational drug therapy for older persons.

17. OLD AGE AND PHARMACOKINETICS

18. Age related increase in the proportion of body fat: causes increase in volume of distribution for lipid-soluble drugs: e.g: benzodiazepines.

19. Age-related decrease in lean body mass: causes 10-15% decrease in total body water: The volume of distribution declines for hydrophilic drugs e.g, alcohol.

20. Plasma albumen concentration decreases in elderly malnorished subjects, especially those with advanced cancer.

21. The plasma-binding of some drugs decreases and the unbound fraction may exceed 50%  increase free drug concentrations and toxicity. e.g, Salicylate, Naproxen, Acetazolamide, Valproate.

22. Age-related decrease in liver mass: 20-50%: during the age span up to 80 years. • Decreased amount of drug-metabolizing enzymes.

23. Associated with that, there is gradual decrease of hepatic blood flow. • Decrease in clearance of drugs.

24. Decrease in elimination by conjugation of some drugs by up to 25%. e.g. Theophylline.

25. Decreased first-pass metabolism of some drugs that are highly extracted by the liver. e.g. Labetalol, Propranolol, Verapamil and Morphine: This results in decreased systemic bioavailability and decreased concentration.

26. Older smokers: Decreased hepatic metabolizing enzymes: increased mortality in older smokers.

27. Malnutrition: e.g. in cancer patients with anorexia. Impairment of drug metabolism. Adjusting of dosage (esp. cancer drugs) is important.

28. Old frail subjects and decreased clearance of acctominophen: Up to 42% in one study.

29. Warfarin: Age-related decline in liver volume. decrease in warfarin dose requirement: may start at age of 50 years.

30. Renal function: Renal mass decreases by 25-30% across the age span.

31. Renal blood flow decreases by 1% per year after age of 50 years.

32. GFR decreases by 35% in healthy individuals between ages 20 and 90 years.

33. In some individuals: this decline does not occur!

34. This GFR decrease affects the clearance of drugs that are secreted or filtered by the kidney.

35. PHARMACODYNAMICS

36. High affinity receptors are diminished. Decline in receptor- effectar coupling. e.g: I.V isoproterenol to increase heart rate in older patients: Compromised More doses are needed.

37. Sensitivity to psychoactive drugs is greater in older persons: e.g anxiolic drugs and hypnotics.

38. Pain management for cancer patients: e.g Morphine and pentazocine. Duration of pain relief is prolonged with increasing age. Probably due to decreased volume of distribution.

39. Anesthesia: Increased brain sensitivity to I.V fentanyl and altentanil.

40. ISSUES IN DRUG PRESCRIBING FOR THE ELDERLY

41. Quality of Drug Prescribing: Several dimensions: • Avoidance of inappropriate medications. • Appropriate utilization of indicated drugs.

42. Monitoring for side effects, and drug levels. • Avoidance of drug-drug interactions. • Involvement of the patient and integration of his/her values.

43. Quality indicators for appropriate medication use in older adults:

44. Cont.

45. Knight, El, Avorn, Ann Intern Med 2001; 135:703.

46. POLYPHARMACY In evaluating subjects on multiple medications, always consider: • Over-the-counter drugs. • Herbal preparations. • Supplements.

47. Around 50% of older patients use 5 or more medications.

48. Older individuals are at greater risk for adverse drug events (ADE), due to changes in pharmacokinatics and pharmacodynamics.

49. Polypharmacy increases the potential of drug-drug interactions.

50. Polypharmacy is a risk factor for falls and hip fractures.