Alterations in drug handling in the elderly Flashcards
(14 cards)
name some risks in older people
- falls
- polypharmacy
- co-morbidities
- adverse effects risk increased
- low blood pressure
- sedation risk increased
- confusion/poor capacity
- poor dexterity
- poor vision/hearing
- frailty
- poor social support
what drugs are particularly risky in older patients
- screening tool of older peoples prescriptions (STOPP) and screening tool to alert right treatment (START)
- Beer’ criteria
- diuretics
- sedating drugs
- NSAIDs
- anticoagulants/antiplatelets
- antihypertensives
- narrow therapeutic index drugs
- complex dose or administration regimens
what factors, specific to this sub set patient population, should be considered
ageing affects both pharmacokinetics and pharmacodynamics
how does ageing affect pharmacokinetics
ageing results in changes that affect ADME
- age related changes in the GIT (A), liver (M) and kidneys (E) include reduced:
- body fat/h2o distribution
- gastric acid secretion
- gastrointestinal motility
- total surface area of absorption
- splanchnic blood flow
- liver size and liver blood flow
- glomerular filtration
- renal tubular filtration
how is distribution affected in ageing
- reduced body mass but increase in body fat, can increase lipophilic drug volume of distribution
- low total body of water can reduce hydrophilic drug volume of distribution
- Lower serum albumin can lead to increased levels of unbound fraction of some drugs
how is metabolism affected in ageing
- liver size and liver blood flow are reduced
- first pass metabolism reduced
- these drugs become more bioavailable
how is excretion affected in ageing
- natural decline in GFR correlates with increasing age
- estimates of renal function limited by frailty
- risk of drug accumulation
- extra care with renal excreted, narrow therapeutic window/toxic drugs
how does ageing affect pharmacodynamics
- molecular and cellular changes that occur with ageing may alter the response to drugs in the elderly
- 2 main headings
- those due to a reduction in homeostatic reserve
- those that are secondary to changes in specific receptor and target sites
describe what occurs due to reduced homeostatic reserve
- orthostatic circulatory responses (blunting of the reflex tachycardia)
- postural control- drugs increasing postural sway
- thermoregulation- there is an increased prevalence of impaired thermoregulatory mechanisms in the elderly
- cognitive function- ageing is associated with marked structural and neurochemical changes in the CNS
what are the age related changes in alpha adrenoreceptors
- alpha 2 responsiveness reduced
2. alpha 1 appears unaffected
what are the age related changes in beta adrenoreceptors
- beta adrenoreceptor function declines with age
- the chrontropic response to isoprenaline infusion is less marked in the elderly
what are the age related changes in benzodiazepine receptors
- the elderly are more sensitive to BDZs although the mechanism is not known
- habituation to BDZs occurs to the same extent in the elderly as the young
what are the principles and goals of drug therapy in the elderly
- avoid unnecessary drug therapy
- effect of treatment on quality of life
- treat the cause than the symptoms
- drug history
- concomitant medical illness
- choosing the drug- efficacy, tolerability and lifestyle
- choosing the most appropriate dosage form
- packaging and labelling
describe the effect of deprescribing
- deprescribing single medications/classes- no effect on mortality
- deprescribing polypharmacy- significant reduction in mortality
- health outcomes of deprescribing polypharmacy- no effect on ADRs, falls, cognition
