Drugs and Polypharmacy Flashcards
List some common iatrogenic drug problems
- anticholinergics: confusion, dry mouth, constipation, blurred vision, urinary retention and orthostatic hypotension
- tricyclics: confusion and unsteady gait
- digoxin toxicity with normal serum conc.
- CNS toxicity with long-acting benzodiazepines
- confusion with narcotics
List some costly medication-related problems/ADRs in older patients
- falls
- cognitive loss/delirium]
- dehydration
- incontinence
- depression
- end result can be: loss of functional capacity, poor QoL, nursing home placement.
which drugs are most associates with admission due to adverse drug reaction (ADR)?
- NSAIDs
- diuretics
- warfarin
- ACEI
- antidepressants
- beta-blockers
- opiates
- digoxin
- prednisolone
- clopidogrel
how does the absorption of drugs change with increasing age?
- physiological changes occur that effect the rate but generally not the extent of absorption from the GI tact - may lead to a delay in onset of action.
- e.g. a reduction in salvia production may result in a reduction in the rate of absoprtion of bucally admnistered drugs e.g. GTN
- exception > levodopa
how does the distribution of drugs change with increasing age?
- body composition changes: reduced muscle mass, increased adipose tissue (fat soluble drugs: ^ Vd, ^ T1/2, ^ duration of action e.g. diazepam), reduced body water (water soluble drugs: dec Vd, ^ serum levels e.g. digoxin)
- protein changes: decreased albumin (dec binding, ^ serum levels acidic drugs e.g. furosemide)
- increased permeability across blood-brain barrier
how does the metabolism of drugs change with increasing age?
- hepatic metabolism is affected by: decreased liver mass and decreased liver blood flow.
- consequences: toxicity due to reduced metabolism/excretion, reduced first pass metabolism > increase in bioavailability with some drugs e.g. propanolol and a decrease in bioavailability of pro-drugs e.g. enalapril
how does the excretion of drugs change with increasing age?
Renal function decreases with age
Reduces clearance and increases half-life of many drugs leading to toxicity
older people exhibit increased sensitivity to particular medicines due to:
- change in receptor binding
- decrease in receptor number
- altered translation of a receptor initiated cellular response into a biochemical reaction
- e.g., diazepam (^ sedation), warfarin (^anti-coagulation)
what are some things to consider when prescribing medication for psychiatric issues in elderly patients?
- care with treating ‘agitation’
- sedatives problematic > increased effects of benzos > falls, confusion
- anti-psychotics: increased adverse effects > postural hypotension, stroke, confusion, movement disorders
- anti-depressants: less effective, more dangerous
what are some things to consider when prescribing analgesic medication in elderly patients?
- opioids: more sensitive to effects, lower doses needed, pethidine and tramadol may be less useful
- NSAIDs: increased adverse effects > renal impairment, GI bleeding
what are some things to consider when prescribing cardiovascular medication in elderly patients?
- digoxin: increased toxicity, lower doses needed
- diuretics: decreased peak effect but reduced clearance (abnormal U&Es), other issues around continence and mobility, often inappropriate indication (swollen legs)
- anti-hypertensives: may have exaggerated effects on BP and HR, more likely to be issues with postural hypotension, ACEis often pro-drugs which may not be metabolised to active form, renal adverse effects.
- anticoagulants: more sensitive to warfarin, greater risk from warfarin i.e. GI bleeding, falls
what are some things to consider when prescribing antibiotics in elderly patients?
Increased adverse effects:
- diarrhoea and c.diff infection
- blood dyscrasias (trimethoprim, co-trimoxazole)
- delirium (quinolones)
- seizures
- renal impairment (aminoglycosides)
