Geriatric Pharmacology Flashcards
What effects does aging have on absorption?
Peak serum concentration may be lower and delayed.
Bioavailabilty (amount absorbed) is unchanged, except for drugs with extensive first-pass effect (less drug is extracted by liver).
What are the effects of aging on volume of distribution?
Lower body water: lower VD for hydrophilic drugs
Lower lean body mass: lower VD for muscle-binding drugs
Increased fat stores: higher VD for lipophilic drugs
Decreased plasma protein: higher percentage of drug that is unbound (active).
What effect does aging have on the liver (metabolism) and kidney (excretion?
Decreased liver blood flow, size and mass = reduced metabolic clearance of drug.
Decreased kidney size, renal blood flow, number of functioning nephrons and renal tubular secretion. End result: LOWER GFR.
What is the difference between Phase I and Phase II metabolic pathways?
Phase I: convert drugs to active metabolites.
Phase II: convert drugs to inactive metabolites that do not accumulate.
Why does serum creatinine stay in the normal range in older people?
There’s less creatinine production due to less lean body mass, but also decreased creatinine excretion due to a lower GFR.
Why don’t you use anti-cholinergics in the elderly?
As you age, there are less cholinergic nerves in the brain. This will amplify the effect of these drugs.
