Drugs and Polypharmacy Flashcards
What happens to absorption in old age
There are physiological changes that effect the rate of absorption of a drug, but no the extent of its absorption
What happens to saliva production in old age
Reduced saliva production and there for a reduced rate of absorption of buccally administrated drugs
Why is there an increased absorption of levodopa in the elderly
enzyme dopa-decarboxylase is reduced
State the two main factors that effect drug distribution in the elderly
Body composition changes and protein binding changes alongside increased permeability across the blood-brain barrier
State how body comp changes in the elderly
Reduced muscle mass, increased adipose tissue and reduced body water
What happens to drugs fat soluble drugs due to increased adipose tissue
Increased volume of distribution, increased half life and increased duration of actio
Example is diazepam
State the effect of reduced body water on water soluble drugs
Increased Vd, increased serum levels (digoxin)
Give examples of the drugs effected by a reduced body water
theophylline, atenolol, propranolol and hydrochlorthiazide
State the main cause of protein binding changes in the elderly
Decreased albumin
State the effects of decreased albumin
Decreased binding, increased free drug and therefore increased serum levels of acidic drugs
State the drugs effected by decreased albumin
cimetidine, furosemide, NSAIDs and sulphonylureas, diazepam, salicyic acid
How is hepatic metabolism effected by increased age
Decreased liver mass and reduced liver blood flow
What are the consequences of reduced liver metabolism
Toxicity and reduced first pass metabolism
What changes excretion of drugs in the elderly
Reduced renal function
What is the consequence of reduced renal function
Reduced clearance and increased the half-life of many drugs leading to toxicity
Why are the elderly more sensitive to particular medication
Change in receptor binding, decrease in receptor numbers and altered translation of a receptor initiatied cellular response into a a biochemical reaction
State the drugs effected by increased sensitivity
Diazepam and warfarin
Why are elderly patients at more risk of drug-disease interactions
Older people have more chronic diseases and these can affect drug pharmacokinetics
State the increased effects of benzos in the elderly
Falls, confusion
State the increased effects of anti-psychotics in the elderly
Postural hypotension, stroke, confusion, movement disorders
Digoxin in the elderly
Increased toxicity, lower doses needed
Diuretics in the elderly
Decreased peak effect but reduced clearance resulting in abnormal urea and electrolytes
Anti-hypertensives in the elderly
May have exaggerated effects on BP and HR
More likely to be issues with postural hypotension
ACE inhibitors often pro-drugs which may not be metabolised to the active form
Renal adverse effects
Anti-coagulants in the elderly
More sensitive to warfarin and greater risk from warfarin
Antibiotics in the elderly
Diarrhoea and c. diff infection
Blood dyscrasias (trimethoprim, co-trimoxazole)
Delirium (quinolones)
Seizures
Renal impairment (aminoglycosides
