Pharmacology in the elderly Flashcards
T/F? Changes in plasma protein binding, body content, and drug metabolism can effect pharmacologic responses in the elderly.
TRUE
What are the two primary plasma proteins?
albumin and alpha 1 acid glycoprotein
What is different about the 2 plasma proteins?
albumin is carrier for acidic compounds…. a-1 acid glycoprotein acts as a carrier of basic and neutrally charged lipophilic compounds (primary carrier of basic drugs, steroids, and protease inhibitors… whereas albumin carries acidic drugs)
While the effects on drug binding are minimal overall, what happens to the serum level of the two plasma proteins in the elderly?
slight decrease in albumin, slight increase in a-1 acid glycoprotein
What are some noted changes in body composition of the elderly?
decrease lean body mass, increase body fat, decrease total body water….
A decrease in muscle mass and increase in body fat results in an overall decrease in total body water. What effect does this have on water-soluble and lipid soluble drugs?
water soluble: smaller volume of distribution (apparent volume into which a drug has been distributed)… higher plasma concentration…. pharm effect will increase
lipid soluble: larger volume of distribution….lower plasma concentration… prolonged rate of elimination
What happens to drug metabolism as a result of aging?
liver volume decreases 20-40%… flow decreases 10% per decade… decreased innate capacity to metabolize drugs…. so overall metabolism decreases
GFR decreases 6-8% per decade… renal function reduced…. ability to excrete drugs decreases
What are elderly considerations for benzodiazepines?
d\t decreased total body water… there is a lower volume of distribution…. so hydrophilic drugs will reach steady state quicker and be gone quicker than lipophilic drugs…
What may contribute to a delayed induction and onset of IV drugs in the elderly?
impaired myocardial pump function, reduced CO, decreased perfusion of organs
What changes are seen in the use of inhaled anesthetics for the elderly?
reduced anesthetic requirement, MAC reduced 4-6% per decade after 40, faster uptake if CO is decreased, exaggerated myocardial depressant effects of VAAs, prolonged recovery d/t increased volume of distribution, decreased hepatic function, decreased pulmonary gas exchange
Why may morphine have prolonged effects?
morphine and morphine 6-glucuronide have analgesic properties and the latter depends on renal excretion…. so decreased renal excretion results in prolonged effects
What are considerations when using remifentanil in the elderly?
twice as potent, up to 50% reduction in bolus dose, 30-50% reduction in infusion rate
What are elderly considerations for NMB’s?
prolonged onset, reduction in clearance and increased elimination half time (except for nimbex)…. elderly men may have prolonged effect from Sux
T/F? You may have to increase the dose of beta adrenergic agents in the elderly.
True: decreased response to beta adrenergic agents…. conduction time is slowed…. sympathetic response decreases b\c decreased number of sympathetic receptors
