Geriatrics and Clinical Pharmacology
Core concepts
Understand aging physiology: reduced renal clearance, decreased hepatic metabolism, altered body composition, and reduced homeostatic reserve. Know the principles of prescribing in older adults - start low, go slow, review regularly, and use tools like the Beers criteria and STOPP/START to identify potentially inappropriate medications. Cover the geriatric syndromes: falls, delirium, incontinence, frailty, and polypharmacy. In clinical pharmacology, know pharmacokinetics (absorption, distribution, metabolism, excretion) and pharmacodynamics, the cytochrome P450 system, and the major drug interactions and adverse effects.
Traps
Examiners test the anticholinergic burden (confusion, urinary retention, constipation) and the risk of benzodiazepines (falls, delirium). Remember that NSAIDs cause AKI and GI bleeding, especially with ACE inhibitors and diuretics (the "triple whammy"). Be careful with dosing in renal impairment - many drugs need adjustment. Watch for the difference between an adverse drug reaction (predictable, dose-related) and an idiosyncratic reaction.
Worked rule of thumb
New confusion in an older adult: think delirium first, look for a cause (infection, drugs, pain, constipation, dehydration, retention), and review the medication list. Anticholinergics and sedatives are frequent culprits.
Key points
- Start low and go slow in older adults.
- Beers criteria identify potentially inappropriate medications.
- Anticholinergic burden causes confusion and retention.
- NSAIDs plus ACE inhibitor plus diuretic increases AKI risk.
- Adjust drug doses for renal function.