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Drug dosing in Geriatric Patients- Pharmacotherapeutics-1
The document discusses the importance of proper drug dosing in geriatric patients, highlighting the demographic growth of the elderly population and their unique health challenges, including polypharmacy and altered drug metabolism. It emphasizes the need for careful prescribing practices, considering factors such as concomitant illnesses, drug interactions, and the efficacy and safety of medications. Guidelines are provided for prescribing, stressing a patient-centered approach to enhance quality of life while minimizing adverse effects.
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Drug dosing in Geriatric Patients- Pharmacotherapeutics-1
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- 2. Introduction • Geriatrics isthe branch of general medicine concerned with the clinical, preventive, remedial, and social aspects of illness in the elderly. • The term “elderly” refers to patients aged 65 years & above. • Currently, more than 70 million people in India are aged over 65 years. • As this number grows, it will become increasingly important for PHARMACISTS to contribute to rational & safe drug use in the elderly.
- 3. • 1901- 4.8% •1981-15.2% • 2001-18% • In addition to this 85 and above population size also increased. • Due to declining infant & child mortality ( due to improved standards of housing, hygiene & nutrition) • Advances in curative and preventive medicine- life expectancy increased. • The significant increase in the number of very elderly people will have important social, financial and health care planning implications.
- 4. • The elderlyhave multiple & often chronic diseases. • Therefore, they are the major consumer of drugs. • In most developed countries, the elderly now account 25-40% of drug expenditures.
- 5. • Commonly usingdrug classes (SYSTEMS) • CVD • CNS • Musculoskeletal system • RS • Common drugs: diuretics, analgesics, hypnotics, sedatives, anxiolytics, antirrhematic and beta blockers • 50% of Patients take at least 1 OTC medications • Overtreatment >< Undertreatment • Long duration and poly pharmacy
- 6. Reason for cautionwhen using medicines in the elderly 1. Increased prevalence of the diseases 2. Polypharmacy 3. Altered drug response 4. Inappropriate prescribing 5. Adverse drug reaction (ADR) 6. Patient non-compliance
- 7. Common diseases andhealth problems affecting the elderly.
- 8. Drug interaction • Asthe number of medicines increases chances of DI also increases • May alter the action • Enhance / reduce the efficacy • Pharmacokinetics • Absorption: • Motility – Anticholinergics &metaclopramide • Chelations & Complexes – Antacids + Digoxin • First pass metabolism- MAOIs + Tyramine
- 11. Pharmacokinetics • Ageing resultsin many physiological changes that could theoretically affect • Absorption • First-pass metabolism • Protein binding • Distribution • Elimination of the drugs
- 12. Age related changesin liver, kidney and GIT are……. Reduced Gastric acid secretion Reduced GI motility Reduced total surface area of absorption Reduced liver size Reduced liver blood flow Reduced Glomerular filtration Reduced renal tubular filtration
- 13. Absorption • The absorptionof the drug changes in geriatrics due to in gastric emptying & reduction of gastric acid output In pH in blood flow to the GIT • Although the absorption of many drug are not significantly change due to these alteration , the digoxin absorption may be slower in geriatric
- 14. Drug absorption maybe altered by GI disorders:- • Enteritis • Malabsorption syndromes • Concomitant use of drugs that affect GI function Laxatives Antacids
- 15. First-pass metabolism • Theintestinal and hepatic degradation or alteration of a drug or substance taken by mouth, after absorption, removing some of the active substance from the blood before it enters the general circulation.
- 17. • After absorption,drugs are transported via portal circulation to the liver, where many lipid-soluble agents are metabolized extensively (more than 90- 95%). • Impaired first- pass metabolism in geriatric population can lead to reduction in systemic bioavailability. • Ex Nifedipine, Verapamil, Nitrates, Propranolol. • Hypotensive effect is enhanced due to impaired 1st pass metabolism.
- 18. Distribution • The amountof body fat increase with the age. • Increase body fat in elderly leads to increase Vd for fat soluble drug. • Ex – Diazepam, Thiopental. • Therapeutic effect is prolonged.
- 19. • Age relatedphysiological changes which may affect drug distribution are: • Reduced lean body mass • Reduced total body water • Increased total body fat • Lower serum albumin level
- 20. • Decrease inthe total body water in elderly leads to decreased Vd for water soluble drug. Ex- Digoxin & Ethanol. • Decrease in the serum albumin level in elderly leads to increased free drug concentration of acidic drugs. Ex- Furosemide & Warfarin
- 22. Renal clearance • Thereis a considerable interindividual variability in renal function in the elderly. • Decrease in Glomerular Filtration Rate (GFR) level in elderly need dosage adjustment of renal cleared drug in elderly.- Rate of clearance decreased (Clcr 1% decreased after 40yrs) • Hence GFR has to be calculated Cockroft-Gault formula & their dosage adjustment has to be made.
- 23. • Reduction indosage of drugs with a low therapeutic index, such as Digoxin & Aminoglycosides, may be necessary. • Dosage adjustment may not be necessary for drugs with a wide therapeutic index, for ex Penicillins. • Altered tubular function – impaired handling of water, sodium and glucose.
- 24. Hepatic clearance • Thesize of the liver decreases with the age. • Enzymes levels also decrease which results in decrease in hepatic clearance. • Hence dosage has to be adjusted based on the hepatic function.
- 25.
- 26. ADR & ADEin elderly
- 31. Guidelines for prescribing fordrug dosing In Geriatric
- 32. 1. Avoid unnecessarydrug therapy Is it really necessary? Is there any alternative methods of treatment? For ex:- For mild hypertension non-drug therapy can be recommended such has life style modification. • If possible hypnotics should be avoided in elderly.
- 33. 2. Effective treatmentto improve quality of life. Drug should not be prescribed to prolong the number of years of life, but it should be prescribed to improve quality of life.
- 34. 3. Treat thecause rather symptoms. • Ex:- Complaint of indigestion in elderly make as symptoms of angina. • Hence unnecessarily they should not prescribe H2 receptor blocker.
- 35. 4.Proper dug history. •Accurate drug history of the patient should be taken in order to minimize drug interaction, adverse drug reaction, & drug duplication.
- 36. 5. Concomitant diseases. •Presence of other medical disorder should be consider ( cardiac, hepatic & renal disorders) before prescribing any medication.
- 37. 6. Choosing thedrug. • The drug prescribe for elderly should be most efficacious & least toxic that is with minimum side effects.
- 38. 7. Dose titration. •Smaller doses should be prescribed to the geriatric based on the concomitant illness, like renal & hepatic function
- 39. 8.Chosing the rightdosage form • The drug prescribed should be easy to swallow hence syrup & suspension are better rather hard tablet & capsule.
- 40. 9. Packing &labeling. • The drug should not be packed in tight container for arthritis patient & instruction should be printed in bold. And easy-to-open container. • The medication can be packed in dossets to improve compliance & avoid confusion
- 42. 10. History ofprevious ADR has to be obtain before prescribing any drug. 11. Methods should be taken to assess & to improve the compliance of the patient.
- 43. 12. The patientsocial history such has smoking, alcohol habit, dietary type should be obtain. • The record of these must maintain to improve therapeutic outcome of the patient.