Flashcards in Elderly Pharm Deck (18):
does amount absorbed (bioavailability) change with age?
how does peak serum concentration change with age
may be lower and delayed
how do drugs with extensive first-pass effect change with age?
bioavailability may increase because less drug is extracted by the liver, which is smaller with reduced blood flow
factors that affect absorption
route of administration, what is taken with the drug, and comorbid illnesses. divalent cations can affect absorption of fluoroquinolones, enteral feedings interfere with absorption of some drugs, drugs that affect GI motility can affect absorption
what happens to gastric pH when you age?
less gastric acid causing higher pH in the stomach. may impact absorption of drugs such as cations.
effects of aging on volume of distribution
decreased body water = lower VoD for hydrophillic drugs
lower lead body mass = lower VD for drugs that bind muscle
increased fat stores = higher VD for lipophilic drugs
lower plasma protein = higher percentage of drug that is unbound
why might metabolic clearance of a drug by the liver be reduced?
aging decreases liver blood flow, size, and mass. liver is most common site of drug metabolism
phase I and phase II pathways
phase I convert drugs to metabolites with greater, lesser, or the same effect as the parent compound. Phase II pathways convert drugs to inactive metabolites that do not accumulate
what phase of metabolism is preferred for old patients
other factors that affect drug metabolism
gender, hepatic congestion from heart failure, smoking
effects of aging on the kidney
decreased kidney size, renal blood flow, number of functioning nephrons, and renal tubular secretion. results in lower GFR
creatinine clearance and aging
decreased creatinine production and lower GFR leads to serum creatinine staying in the normal range, masking change in creatinine clearance!
2 ways to measure creatinine clearance
24 hour urine collection. Crockroft and Gault equation
uses correct drug, prescribes correct dosage, targets the correct condition, is appropriate for the patient
most common drugs involved in ADE
cardiovascular, CNS, and musculoskeletal meds. meds with a narrow margin of safety
factors that increase risk of drug-drug interactions
increased number of meds consumed, multiple prescribers, multiple pharmacies, physiologic and pharmacokinetic changes
most common adverse effects of drug-drug interactions
confusion, cognitive impairment, arterial hypotension, acute renal failure