Prescribing for Older Adults

Flashcards covering physiological, pharmacokinetic, and pharmacodynamic changes in older adults, alongside polypharmacy, deprescribing, and structured medication review frameworks.

What changes occur in the cardiovascular system with ageing?

Reduced elasticity of arteries and cardiac muscle, increased systolic arterial pressure, bradycardia, and postural hypotension due to reduced reflex tachycardia.

What age-related physiological changes affect the renal system?

Decreased kidney weight (due to loss of nephrons), decreased renal blood flow, decreased glomerular filtration rate (GFR), altered thirst response, reduced ability to maintain acid/base balance, and reduced ability to cope with dehydration or fluid loading.

What physiological changes occur in the gastrointestinal (GI) tract with age?

Decreased production of stomach acid, decreased absorption of some substances (such as calcium and iron), reduced surface area for absorption, slower gastric emptying, slower intestinal motility (increased transit time), reduced stomach size, reduced mucosal protection, and reduced active transport mechanisms.

What anatomical and circulatory changes take place in the liver with advancing age?

A reduction in liver volume and a reduction in liver blood flow (particularly after the 6th decade).

Why is there an increased risk of hypothermia in older adults?

Due to altered perception of cold, a reduced shiver reflex, and less physical activity leading to less heat generation.

What are the 5 tissue compartments that can alter body composition without changing body weight or BMI?

Adipose tissue, bone, CNS, muscle, and plasma.

How does tissue body composition typically shift in older adults?

There is an increase in the proportion of body fat, a decrease in muscle mass, and a decrease in bone mineral density.

What sensory impairments are common in older age groups according to epidemiological estimates?

Over $80\%$ of people over 65 have some visual impairment, and over $50\%$ of people over 60 have some hearing loss.

What changes occur in immune response and brain sensitivity in older age?

The brain develops increased sensitivity to toxic effects of infections, electrolyte imbalances, and drug side effects. Immunity declines: infections become acute rapidly, herpes zoster and TB reactivations are common, and incidence and mortality from pneumonia and influenza increase.

How does altered gastric physiology affect drug absorption in older adults?

Reduced acid secretion occurs in $25\%$ of older adults; increased gastric pH can cause premature release of enteric-coated formulations, and active transport mechanisms for $B_{12}$, calcium, and iron are reduced.

How does an increased proportion of body fat alter the distribution of lipophilic drugs?

It increases the volume of distribution and prolongs the elimination half-life for highly lipophilic drugs (e.g., benzodiazepines enter adipose tissue and are cleared more slowly).

What effect does a decrease in total body water have on drug distribution?

It decreases the volume of distribution for water-soluble drugs, potentially leading to higher serum concentrations.

What changes occur to plasma proteins with ageing, and which drugs carry high toxicity risks as a result?

Serum albumin decreases while $\alpha_1$-acid glycoprotein increases. In acute illness or malnutrition, a drop in albumin increases unbound (free) drug levels; drugs with high protein binding like phenytoin and warfarin carry a high risk of toxic effects.

How is hepatic drug metabolism affected by ageing, and why are liver function tests (LFTs) limited?

Hepatic metabolism via the CYP enzyme system decreases, and first-pass metabolism decreases by about $1\%\text{ per year}$ after age 40. LFTs do not reflect drug-metabolising capacity.

At what rate does creatinine clearance decline after age 30, and why can serum creatinine be misleading?

Creatinine clearance declines by an average of $8\,\text{mL}$ per decade. Serum creatinine may remain within normal limits despite reduced GFR because older adults produce less creatinine due to reduced muscle mass and lower activity.

What baseline renal function should clinicians assume when dosing medications in elderly patients?

Assume a GFR of $20\text{--}50\,\text{mL/min}$ (mild failure) and adjust doses accordingly (e.g., diazepam half-life can rise to 96 hours; thiazides lose efficacy when GFR is below $30\,\text{mL/min}$).

What pharmacodynamic receptor changes occur in older adults?

A reduction in the number of beta receptors, reduced $\beta_1$ receptor sensitivity, and increased receptor affinity leading to heightened sensitivity to warfarin.

Which pharmacodynamic alterations heighten the risk of falls in older patients?

Impaired baroreceptor function causes vasodilators to provoke postural hypotension, while impaired homeostasis increases sensitivity to diuretics.

Which drug classes are associated with impaired thermoregulation and hypothermia risk in the elderly?

Phenothiazine antipsychotics and opioids.

What are the four scenarios defining 'problematic polypharmacy' according to the Royal Pharmaceutical Society (RPS)?

1) Prescribing drugs that are no longer clinically indicated; 2) Where the benefit does not outweigh the harm; 3) Where drug combinations cause or risk harm; 4) Where managing the regimen is impractical or causes harm/distress.

What is a 'prescribing cascade'?

A process where an adverse drug reaction is misdiagnosed as a new medical condition, prompting the prescription of a new drug to treat the side effect (e.g., prescribing a diuretic for amlodipine-induced ankle oedema).

What is 'medication creep' and what causes it?

When a patient continues a medication that is no longer needed or beneficial, driven by uncertainty over who should stop it, reluctance to question colleagues' decisions, and lack of time to review repeat prescriptions.

What do NNT and NNH represent, and why might NNT be less accurate near end of life?

Number Needed to Treat (NNT) is the number of patients treated to prevent one bad outcome; Number Needed to Harm (NNH) is the number treated for one patient to experience harm. In older adults near end-of-life, baseline risk is higher and remaining lifespan may be too short to accrue treatment benefit.

Which drug classes commonly require particular caution when prescribed to older adults?

NSAIDs, opioids, diuretics, anticoagulants, antihypertensives, insulin/oral hypoglycaemics, and antibiotics (due to Clostridioides difficile risk).

What are the 4 principles of Medicines Optimisation?

Principle 1: Aim to understand the patient’s experience; Principle 2: Evidence based choice of medicines; Principle 3: Ensure medicines use is as safe as possible; Principle 4: Make medicines optimisation part of routine practice.

What is deprescribing and how should it be executed?

The process of dose reduction or discontinuation of medications that may cause harm or no longer provide benefit, conducted within a review of polypharmacy using shared decision-making with the patient.

What symptoms constitute the anticholinergic burden in older patients?

Constipation, blurred vision, dry mouth, dry eyes, urinary retention, falls, sedation, photophobia, delirium, agitation, and cognitive impairment.

What are the two components of the STOPP/START criteria?

STOPP: Screening Tool of Older Persons’ potentially inappropriate Prescriptions; START: Screening Tool to Alert doctors to the Right Treatment.

What are the 3 categories in the BEERS criteria?

1) Potentially inappropriate medications and classes to avoid in older adults; 2) Potentially inappropriate medications and classes to avoid in older adults with specific diseases/syndromes; 3) Medications to be used with caution in older adults.

What are the 7 steps in the 7-step medication review process?

1) Aim: What matters to the patient?; 2) Need: Identify essential drug therapy; 3) Need: Does the patient take unnecessary drug therapy?; 4) Effectiveness: Are therapeutic objectives being achieved?; 5) Safety: Is the patient at risk of ADRs or suffers actual ADRs?; 6) Sustainability: Is therapy cost-effective and environmentally sustainable?; 7) Patient-centred: Is the patient willing and able to take therapy as intended?

What does the NO TEARS medication review mnemonic stand for?

Need and indication, Open questions, Tests and monitoring, Evidence and guidelines, Adverse events, Risk reduction or prevention, and Simplification and switches.

What three tasks should be completed before talking to the patient during a structured medication review?

Review notes, check medical background, and check recent investigations.