Prescribing in Older Adults

describe the diversity in older age

• chronological age is a poor marker of biological age → wide range of physical capacity across older adults

• biological ageing:

  • accumulation of cellular damage over time

  • generalised decline in function

  • increased probability of death

  • complex multifactorial process

  • significant inter-individual variation

what does it mean when law states that age is a protected characteristic?

• cannot discriminate based on age → cannot assume all older adults are frail, have poor memory etc

if age is not a good indicator of biological ageing, how can we determine biological age in practice?

assess frailty

• frailty = state of increased vulnerability to suboptimal restoration of homeostasis after a stressor event, and increases the risk of adverse outcomes

describe how frailty can impact quality of life

• decline in multiple physiological systems

• non-frail person will have a slight decline in functional ability during a minor illness, then return to baseline

• a frail person will have a more significant decline during minor illness, have a longer recovery period and will not return to baseline :. every incident reduces the baseline

• increased vulnerability to minor stressor events and reduced physiological resilience

describe the pathophysiology of frailty

• physiological dysregulation across multiple systems → musculoskeletal, metabolic and stress response systems

• numerous genetic, epigenetic and environmental factors that contribute to frailty resulting in decreased physiological reserve

describe the frailty phenotype

• weakness

• weight loss

• slow gait

• fatigue

• low activity

• more at risk of ADRs

what is the cumulative deficit model for frailty?

• model used in primary care systems

• states that the more conditions a patient has, the more likely they are to be frail

• factors contributing = biological, physiological and social domains

• ability to cope with external stressor

why is the cumulative deficit model not used in hospital- what is used instead?

• cumulative deficit model has a lot of variables across the biophysical domains that can be hard to operationalise in clinical practice

• use the rockwood score instead in hospital

what is the rockwood scale?

• frailty assessor used in hospitals

• scored from 1-9 → 1 being very fit, 9 being terminally ill

what is important to consider when treating the eldery?

• challenge bias → not all old people have the same capacity

• ageing well has a societal benefit as well

• preventative approaches to multimorbidites are key to prevent frailty

• assess appropriateness of polypharmacy

• frailty is a good approach to assessing biological age

describe the ageing process

• decline of biological functions

  • decline in renal, hepatic, cardiac, respiratory, musculoskeletal systems and ability to adapt to metabolic stress

• change in response to receptor stimulation

• decrease in homeostasis or counter regulatory mechanisms

• loss of body water and increase in body fat

what aspects of ageing can affect absorption?

• decreased intestinal flow

• increased gastric pH

• decreased SA for absoprtion

• decreased GI motility, gastric emptying and gastric secretions

describe the clinical significance of ageing on absorption

not usually significant but this does cause:

• reduced B12, calcium, and iron absorption as their active transport mechanisms are reduced

• increases absorption of levodopa because there is less dopamine decarboxylase enzymes in gastric mucosa :. less is broken down :. more peripheral side effects of levodopa

what aspects of ageing can impact distribution?

• decreased body mass and muscle mass

• increased body fat → fat soluble drugs have higher Vd :. distributes into tissue :. lower plasma concentration of drug e.g. patients are more susceptible to effects of diazepam as it is lipid soluble

• decreased body water → water soluble drugs have reduced Vd :. increased plasma concentration of drug as lower distribution into tissues e.g. decreased risk of toxicity with gentamicin, digoxin, theophylline

• decreased albumin → protein bound drugs have reduced binding :. increased free drug :. susceptible to toxicity e.g. digoxin

what is extraction ratio?

amount of drug cleared when it passes through the liver

• can use this to estimate liver function

what impact does ageing have on metabolism?

• decreased first pass metabolism :. increased bioavailability :. lower doses e.g. propranolol, labetalol

• decreased hepatic flow → reduced clearance of high extraction ratio drugs :. prone to ADRs

• decreased enzyme activity → less clearance, less activation of prodrugs e.g. analapril, perindopril

what effect does ageing have on elimination?

• renal function declines with age → most important age related change

• decreased renal blood flow

• decreased number of functioning nephrons

what types of drugs should be cautioned in age related renal impairment?

• :. expect accumulation of renally cleared drugs and metabolites → water soluble antibiotics, diuretics, dogoxin, lithium, NSAIDs

• avoid nephrotoxic drugs e.g. gentamicin and other aminoglycosides (= exclusively renally excreted)

• some drugs stop being effective with reduced renal function e.g. nitrofurantoin is cleared by liver and won’t work if it is not adequately cleared :. increased likelihood of ADRs and resistance

how can you estimate renal function?

cockgroft-gault equation is favoured over eGFR for older adults as it accounts for age, weight, gender :. more specific → eGFR is an average per body surface area :. not specific

• creatinine = product of muscle breakdown and filtered by kidneys

describe the different stages of renal impairment

• stage 1 → kidney damage with normal/increased GFR → CrCl of 90 or more WITH proteinuria

• stage 2 → kidney damage with mild/reduced GFR → CrCl of 60-98

• stage 3 → moderate reduced GFR → CrCl of 30-59

• stage 4 → severely reduced GFR → CrCl of 15-29

• stage 5 → kidney failure → CrCl of less than 15 or dialysis

what prescribing adjustments should be made for older adults?

• initiate with low dose

• titrate up against response/physiological parameter/target dose

• in acute illness, there is an increased risk of AKI :. reduce dose or hold nephrotoxic or renally cleared drugs

• consider sick day rules

• avoid drugs that are substantially excreted by kidneys where possible

• use with caution if needed and consider relevant drug monitoring

which drugs require sick day rules?

• S → SGLT2i

• A → ACEi

• D → diuretics

• M → metformin

• A → ARBs

• N → NSAIDs

• S → sulphonylureas

describe pharmacodynamics in order adults

• less predictable in ageing

• changes in organ/system response to homeostatic mechanisms :. exaggerated drug response

• changes in cell/receptor sensitivity and response

describe receptor sensitivity in ageing adults

• increased CNS sensitivity → increased ADRs like agitation, confusion etc with opiates, benzodiazepines, psychotropics

• increased GI sensitivity → increased ADRs like nausea, constipation etc with NSAIDs, SSRIs, prednisolone :. consider prescribing PPIs

• increased benzodiazepine receptor sensitivity → increased and prolonged sedative effects :. use lower doses and shorter acting drugs e.g. lorazepam over diazepam

• increased anticholinergic receptor sensitivity → increased ADRs like confusion, blurred vision, constipation etc with amitriptyline, oxybutynin, hyoscine

describe the organ/system changes that occur with ageing

• blunting of reflex tachycardia :. more susceptible to falls and postural hypotension

• poor posture :. increased fall occurrence

• structural and neuro-chemical changes in CNS e.g. reduced dopamine, ACh :. leads to confusion

• impaired thermoregulation :. hypothermia

• reduced visceral muscle formation :. constipation, urinary incontinence

• reduced venous return :. thrombotic events

if you are starting an elderly patient on an antihypertensive, what should you consider?

give 1st dose at night → less active at night :. accounts for postural hypotension that is common in ageing adults → monitor and assess if it is okay to give during daytime

what is polypharmacy?

5 or more srugs

what are the 5 geriatric Ms?

• mind

• medications

• mobility

• multi complexity

• matters most (what matters most to patient)

what is important to consider with polypharmacy in older adults?

optimising and deprescribing inappropriate medications

describe the anticholinergic burden in order adults

• some medications have anticholinergic side effects e.g. dry mouth, constipation, blurred vision

• in patients over 65, anticholinergic adverse effects can be confusion, dizziness, falls

• anticholinergic burden is the cumulative effect of taking 1 or more medications with anticholinergic activity

• medications are given a score of 0 = no anticholinergic activity to 3 = high anticholinergic activity

• when accounting for all medications, a combined score of 3 or more is associated with increased cognitive impairment, functional impairment, falls and morbidity in older adults

• should be stopping meds with high anticholinergic score or changing to a drug with lower score

describe the subtleties of medicine related harm in older adults

• ADRs of drugs are not easily recognising as they can present as other geriatric symptoms e.g. dizziness :. have to be alert and assess if medication can be causing these symptoms

• older people can sometimes expect less than optimal health and care :. less likely to complain

what did the PRIME study show?

• aimed to identity the incidence, preventability, severity and cost of post-discharge medicine related harm in older adults

• recruited patients from different hospitals and followed them up for 8 weeks

• identified medicine related harm using primary care records, patient interviews, and hospital readmission

• found 37% experienced medicines related harm

what can we do to reduce medicine related harm?

• accurate and timely medicine reconciliation

• stop medicines where harm outweighs benefit → deprescribing

• risk stratification and biopsychosocial approach

• see the person and what matters most to them

• understand their environment

what is the biopsychosocial model of medicine related harm?

• approach that is individualised, multiagency, multifactorial and dyanmic

• if we modify prescribing based on e.g. interactions, renal function etc, then we should also consider modifying social care e.g. carers to help medicine administration

describe appropriate and problematic polypharmacy

• appropriate → use of multiple medications that are clinically indicated, optimised and prescribed according to best evidence :. extend and improve QoL

• problematic → benefits do not outweigh harm, combinations cause or risk harm, usage becomes unmanageable or distressing

what is hyperpolypharmacy?

10 or more medications

what is oligopharmacy?

intentional practice to minimise the number of regular medications → aim = less than 5

what is overprescribing?

• use of a medicine where there is a better non-medicine alternative

• use of a medicine that is inappropriate for the patient’s circumstances and wishes

what is the prescribing cascade?

model that refers to initiation of 1 drug, this results in an ADR, then initiating a new drug to treat the ADR → cycle continues

• can be a result of overprescribing

how can we address overprescribing?

• collaboration, support and behaviour change from clinicians, patients and their carers

• personalised care and shared decision making

• medicine optimisation is key to addressing overprescribing

• framework that ensures patients get right medications, at the right time, in the right doses

what is medicines optimisation?

outcome focussed approach o the safe and effective use of medicines that takes into account the patient’s values, perceptions and experiences of taking medications

what is deprescribing?

• tapering, stopping, discontinuing or withdrawing medications that are no longer appropriate, beneficial or wanted

• required follow up review to assess how patient is handling once off the medication

• reduces harm → minimises ADRs, interactions and errors

• improves outcomes → focuses on effective treatments, avoids unnecessary interventions

• enhances QoL → simplified regimen, adherence, less side effects

• cost effective → lower healthcare costs

describe evidence based prescribing in older adults

have to consider that patients with significant comorbidities or limited lifespan may not want the best evidence based medications → may not align with current priorities due to e.g. side effect profile etc

describe the STOPP-START tool for use in older people

• decision aid to support medications review in older people

• suggestions related to problems in prescribing for older people to reduce medication burden and add in beneficial therapy

• Screening Tool of Older People’s Prescription

• Screening Tool to Alert to Right Treatment

• using STOPP/START criteria as an intervention within 72 hrs of admission significantly reduces ADRs and average length of stay by 3 days