Prescribing in Older Adults

Prescribing in older adults means choosing, dosing, monitoring and stopping medicines in people aged 65 years or over, where age-related change in clearance and sensitivity, multimorbidity and frailty narrow the margin between benefit and harm. Most preventable harm comes from renal overdosing, sedatives and anticholinergics, hypotension, hypoglycaemia, bleeding and prescribing cascades. The working rule is to start low, titrate slowly and review benefit against time to benefit.

Pharmacokinetics. Renal clearance and lean mass fall with age, so serum creatinine overestimates kidney function. Hepatic blood flow falls, albumin is lower in illness, and rising fat mass prolongs the half-life of lipophilic drugs such as diazepam.

Pharmacodynamics. Sensitivity is greater to sedatives, opioids, antipsychotics, anticholinergics, antihypertensives and QT-prolonging drugs. Blunted baroreflexes make postural hypotension common.

Assessment before prescribing. Record weight, creatinine clearance by Cockcroft-Gault, eGFR, sodium, potassium, liver tests, lying and standing blood pressure, cognition, swallowing, continence, falls in the past year and every medicine taken, including over-the-counter and herbal products.

Goals of care. Agree what matters to the person, such as function, staying out of hospital or comfort, before adding preventive medicines.

Use non-drug measures first for insomnia, constipation, low mood, mild pain and behavioural symptoms. Choose once-daily regimens, avoid drugs with active renally cleared metabolites, and add one change at a time.

Prescribing cascades. Amlodipine oedema treated with furosemide, metoclopramide parkinsonism treated with levodopa, and anticholinergic urinary retention treated with an alpha-blocker are common. Ask whether a new symptom is an adverse effect before adding a drug.

Formulation. Do not crush modified-release or enteric-coated tablets. Use liquid or dispersible forms when swallowing is poor, and check that the product can be opened.

Special groups. In dementia, supervise administration and simplify timing. In care homes, document an indication and a review date for every as-needed sedative or antipsychotic. Where medicines come from several facilities or pharmacies, ask the person to bring every container to each visit.

Renal adjustment. Use creatinine clearance by Cockcroft-Gault for most dose thresholds and eGFR for staging. In frail people with low muscle mass both still overestimate function, so use the lower figure for narrow-margin drugs.

Hepatic adjustment. Halve the starting dose of hepatically cleared drugs in moderate impairment (Child-Pugh B) and avoid those with high first-pass effect in severe impairment (Child-Pugh C) unless a specialist advises.

Starting dose. Begin renally cleared or central nervous system active drugs at 25% to 50% of the usual adult dose and lengthen the interval between increases to 2 to 4 weeks.

Monitoring. Check lying and standing blood pressure at every titration, sodium and potassium 1 to 2 weeks after starting or increasing a diuretic, ACE inhibitor, angiotensin receptor blocker or SSRI, and weight, cognition and falls at each review.

Sick day rule. During vomiting, diarrhoea or poor intake, withhold metformin, ACE inhibitors, angiotensin receptor blockers, diuretics, SGLT2 inhibitors and NSAIDs, and restart after 24 to 48 hours of normal eating and drinking.

Stopping. Stop any medicine with no current indication, no benefit or harm that outweighs benefit. Withdraw one drug at a time, and taper benzodiazepines, antidepressants, antipsychotics, beta-blockers and corticosteroids given for over 3 weeks.

Common prescribing errors. Full adult doses in low-weight people, duplicate paracetamol in combination products, weekly drugs given daily, continuing short-course drugs indefinitely, and unreviewed as-needed sedatives.

Referral and escalation. Refer to a geriatrician or clinical pharmacist for 10 or more regular medicines, recurrent falls, delirium, unexplained functional decline, or conflicting disease treatments.