Title NCM 114 MIDTERMS RLE ✅

NCM 114 MIDTERMS BY TONS and MADS IV and Drug computations with gerontologic considerations Drug Dosage Calculations - required when the amount of medication ordered (or desired) is different from what is available on hand for the nurse to administer. DRUG THERAPY IN THE ELDERLY PHYSIOLOGIC CHANGES AFFECTING DRUG ACTION As a person ages, gradual changes occur in human physiology. Age-related changes may alter therapeutic and toxic effects of drugs. I. BODY COMPOSITION A. Proportions of fat, lean tissue and water in the body change with age. B. Total body mass and lean body mass decrease. C. proportion of body fat increase. D. Affect relationship between drug’s concentration and solubility in the body. E. Water-soluble drug (gentamicin) - not distributed to fat. 1. Less lean tissue → more drug remains in the blood, → toxic levels can result. F. Pentobarbital - distributed to fat; produce lower levels. II. GASTROINTESTINAL FUNCTION A. Decrease gastric acid secretion and GI motility → slow emptying of stomach contents and movement of intestinal contents through entire tract B. More difficulty absorbing medications - significant problem with drugs having narrow therapeutic range (digoxin) in which any change in absorption can be crucial. III. HEPATIC FUNCTION A. Liver’s ability to metabolize certain drugs decreases due to diminished blood flow to the liver ( age-related decrease in cardiac outplut) B. Medications (esp secobarbital): liver reduced ability to metabolize drug → hangover effect due to CNS depression. C. Elimination of these medications is highly dependent on the liver. D. Decreased hepatic function may cause: 1. More intense drug effects due to higher blood levels 2. Longer-lasting drug effects due to: Prolonged blood concentrations 3. Greater incidence of drug toxicity IV. RENAL FUNCTION A. Most elderly persons’ renal function is usually sufficient to eliminate excess body fluid and waste. However, ability to eliminate some medications reduced >50% B. Many medications (ex. digoxin) excreted primarily through kidneys. 1. Kidney’s ability to excrete decreased → high blood concentrations → Digoxin toxicity (anorexia, nausea and vomiting) C. Drug dosages - modified to compensate for age-related decreases in renal function. 1. Laboratory tests: BUN and serum creatinine, to provide expected therapeutic benefits without the risk of toxicity. V. ADVERSE DRUG REACTIONS A. Elderly - twice as many adverse drug reactions from greater drug consumption, poor compliance and physiologic changes. B. S/S: confusion, weakness lethargy; often mistakenly attributed to senility or disease. C. Most of serious reactions in the elderly: diuretics, digoxin, corticosteroids, sleep medications and nonprescription drugs. D. Diuretic toxicity 1. Total body water decreases with age 2. Normal doses of potassium wasting diuretics (hydrochlorothiazide and furosemide) result in fluid loss and dehydration 3. Deplete serum potassium → weakness, raise blood uric acid and glucose levels, complicating pre-existing gout and diabetes mellitus. E. Digoxin toxicity 1. Renal function and rate of excretion decline → digoxin concentrations toxic levels → nausea, vomiting, diarrhea and cardiac arrhythmias. 2. Severe toxicity prevented by observing early signs: appetite loss, confusion or depression. F. Corticosteroid toxicity 1. Short-term effects: fluid retention, psychological manifestations ranging from mild euphoria to acute psychotic reactions. 2. Long-term effects: osteoporosis (prednisone or related compounds for months or years) 3. Prevention: observe subtle changes in appearance, mood, mobility, signs of impaired healing and fluid and electrolyte disturbances. G. Sleep medication toxicity - 1. Sedatives or sleeping aids, such as flurazepam, cause excessive sedation or residual drowsiness. H. Nonprescription drug toxicity 1. Aspirin and aspirin-containing analgesics used in moderation, toxicity is minimal a) prolonged use: GI irritation and gradual blood loss resulting in severe anemia. b) Anemia from chronic aspirin consumption - elderly most vulnerable (reduced iron stores) 2. Laxatives: diarrhea in elderly patients who are extremely sensitive to drugs such as bisacodyl. 1