geriatric pharmacology Flashcards
drug absorption
physiological changes that occur affect rate for absorption but not extent of GIT absorption
e.g. reduced saliva production - reduced rate absorption bucally asdmin drugs e.g. GTN
absorption of medications used for Parkinson’s
absorbed to greater extent need to use lower doses
distribution changes
reduced muscle mass
increased adipose tissue: fat soluble drugs inc volume distribution and hald life so inc duration action
reduced body water - inc serum levels water soluble drugs
decreased albumin - more free drug
inc permeability BBB
metabolism changes
decreased liver mass and blood flow
toxicity due to reduced metabolism
reduced first pass metaolism: inc bioavailblity some drugs, and less availabiliy prodrugs
excretion changes
renal function declines
reduces clearance and increases half-life leading to toxicity
pharmacodynamic changes
inc sensitivity to some medicines
due to
- change receptor binding
- decrease receptor numbers
- altered translation of receptor initiated cellular response into biochemical reaction
principles prescribing old people
- lower doses
- titrate up
- review medicines regularly
- simple regimens
- consider compliance issues
de-prescribing
to reduce, substitue, discontue drug
reasons to de-prescribe
- ADR
- drug-drug interaction
- drug-disease interaction
- better alternative
- not effective, indicated
- minimise polypharmacy
what cause most adverse effects
anticholinergics
sedatives
opiods in older people
more sensative to effect
lower dose needed
NSAIDs in older people
inc adverse effects: renal impairment, GI bleeding
digoxin older people
inc toxicity
lower dose
diuretics oler people
decreased peak effect but reduced clearance: abnormal urea and electrolytes
issues around continence and mobility
anti-HTN in old people
exaggerated effects on BP and HR
more likely to be issues postural hypotension
