DRUGS IN GERIATRICS

2. DRUGS IN GERIATRICS Dr AZZA ELSHERBINY Assistant professor of pharmacology

3. By the end of this lecture the student should be able to describe: • 1-The changes in physiological functions in elderly • 2-The changes in pharmacokinetics in elderly • 3-Pharmacodynamics changes in elderly • 4-Drug interactions in elderly • 5-Changes in drug effects in elderly • 6-Adverse drug reactions in the elderly • 7-Practical aspects of geriatric pharmacology

4. GENERAL CONSIDRATIONS • 1-An increasing number of adults ≥65 years are living with multiple health problems • 2-There are more women than men among older population. • 3-Among all persons ≥65 years of age, the five leading causes of death are heart diseases • , cancer, stroke, chronic obstructive pulmonary diseases, influenza and diabetes • 4-There is high incidence of adverse effects in elderly due to polypharmacy, reduced drug elimination, multiple disease states and ↑ drug sensitivity • 5-Other problems in elderly are patient compliance, memory changes, hear loss and ↓ vision

5. PHARMACOKINETIC CHANGES IN THE ELDERLY • -Physiological changes associated with aging, diseases and pharmacological factors can affect pharmacokinetic parameters. • These changes can alter drug response

6. Absorption: • Can be affected due to physiological changes:- • 1-Delayed gastric emptying rate • 2-↑ Gastric pH •  3-↓ splanchnic blood flow • 4-↓ absorptive surface • 5-Impaired intestinal motility

7. Disease states:- e.g. • 1-Achlorhydria • 2-Diarrhea • 3-Gastrectomy • 4-Malabsorptive syndromes • 5-Pancreatitis

8. Pharmacological factors:- e.g. • 1-Drug interactions • 2-Antacids • 3-Anticholinergics • 4-Cholstyramine • 5-Food

9. Distribution • Physiological changes • What is the effect of the changes in serum albumin and in body fats on drug distribution? • 1-↓ cardiac output • 2-↓ total body water • 3-↓Lean body mass • 4-↓ Serum albumin • 5-↑ α1-acid glycoprotein • 6-↑ body fat • QUIZE:- • What is the effect of the changes in serum albumin on drug distribution?

10. Disease states • 1-CHf • 2-Dehydration • 3-Edema • 4-Ascites • 5-Hepatic failure • 6-Malnutrition • 7-Renal failure

11. Pharmacological Factors • 1-Drug-drug interactions • 2-Protein binding(displacement) can you provide examples?

12. Metabolism • 1-↓ Hepatic mass • 2-↓ Enzyme activity • 3-↓ Hepatic blood flow • Explain the following, ↓ enzyme activity at old age?

13. Disease states • 1-CHF • 2-Hepatic failure • 3-Malignancy • 4-Malnutrition • 5-Thyroid disease • 6-Viral infection

14. Pharmacological Factors • 1-Alcohol • 2-Smoking • 3-Induction of metabolism • 4-Inhibition of metabolism • Explain the effects of both enzyme induction and inhibition on drug response?

15. Excretion • Physiological changes • 1-↓ Renal blood flow • 2-↓ GFR • 3-↓ Tubular secretion • 4-↓ Renal mass • ↓renal elimination↑adverse effects of drugs (drugs eliminated by kidney) • Drugs highly dependent on renal function for elimination • (Aminoglycosides, acetazolamide, allopurinol, amantadine, amiloride, atenolo, cephalosporines, • Clonidine, fluconazole, H2 antagonists, enalapril……………………………etc…)

16. PHARMACODYNAMICS CHANGES IN THE ELDERLY • These changes due to inefficient homeostatic adjustments or receptors sensitivity

17. Homeostasis • Orthostatic or postural hypotension occurs as a result of impaired baroreceptor function • And a failure of cerebral blood flow auto regulation. Can be aggravated by • 1-Sympatholytics • 2-Volume-depleting drugs and vasodilating agents • These can contribute to falls in blood pressure. • Most common drugs which are used and produce interfere with homeostasis • 1-TCAS:- hypotension,and has other side effects such as tremors, cardiac arrhythmias, sedation • 2-Antihypertensive;- most of them causes postural hypotension

18. Impaired in coordination in old age • -Benzodiazepines and sedative hypnotics:- sedation, weakness, ↓ coordination, confusion • -Narcotic analgesics:- sedation, ↓ coordination, confusion • -Antipsychotics:- sedation, extra pyramidal effects

19. Receptor sensitivity changes • can lead to exaggerated response (e.g. nitrazepam, heparin, warfarin) • 1-A decline in the dopamine system ↑ sensitivity to dopamine blocking agents(e.g. neuroleptics, metoclopramide) • 2-Cholinergic deficits in the central nervous can ↑ susceptibility to confusion caused by ant-cholinergic • Agents • What are the drugs that can induce confusion in older patients?

20. ADVERSE DRUG REACTIONS IN THE ELDERLY • 1-Studies have shown that the percentage of patients with adverse reactions↑ from about 10% • When a single drug is being taken nearly 100% when ten drugs are taken • 2-What are the other reasons for high incidence of errors in prescribed drugs?.

21. DRUG-DRUG INTERACTIONS • -Enzyme inhibitors:-e.g. • Cimetidine(H2 blocker) inhibits the hepatic metabolism of many drugs including phenytion • Mention other drugs are affected by liver enzyme activity? • -Enzyme inducers • What are the enzyme inducers, explain their effect on other drugs?

22. PRACTICAL ASPECTS OF GERIATRIC PHARMACOLOGY • Drug therapy has considerable potential for both helpful and harmful effects in elderly • This balance may be tipped in the right direction by adherence to a few principles • 1-Take a careful drug history, why? (Drug-drug interaction, drug induce disease, drug • Treating disease) • 2-Prescribe only for a specific indication and real need of the drugs

23. PRACTICAL ASPECTS OF GERIATRIC PHARMACOLOGY • 3-Define the goal of drug therapy, start small dose and increase gradually • Wait at least 3 half-lives of the drug, until reach the expected response (why), • If no improvement↑ dose if no response shift to a different drug • 4-Maintain a high index of suspicion regarding drug reactions and interactions in elderly • 5-Simplify the regimen as much as possible (↓ number of drugs being taken, • Collect the drugs that can be taken at same time of the day)