Pharmacotherapy and Medication Management
Domain 2 - Pharmacotherapy and Medication Management
This domain tests medication management as a process rather than a list of first-line drugs: obtaining an accurate medication history, matching therapy to the patient's physiology, detecting and preventing drug-related problems, and knowing when to stop a drug.
Start with a medication history you can defend
- Build a best possible medication history (BPMH) from at least two sources - the patient, a caregiver, community pharmacy records, blister packs, a recent discharge summary.
- Reconcile at every transition of care; an unreconciled discharge list is a classic exam scenario.
- Ask about non-prescription use: OTC products, herbals, cannabis, vaping, samples, and medications borrowed from family.
Match the drug to the physiology
- Renal function: estimate creatinine clearance (Cockcroft–Gault is usual for drug dosing) and adjust renally cleared drugs - DOACs, gabapentin, metformin, many antimicrobials.
- Hepatic function: use Child–Pugh to reason about hepatically metabolized drugs.
- Age: apply Beers or STOPP/START criteria; quantify anticholinergic burden with a tool such as the ACB scale.
- Interactions: classify them as pharmacokinetic or pharmacodynamic and say what you will measure, not only that you will "monitor."
Prescribing cascades and deprescribing
A new drug causes a symptom that triggers another drug - that is a cascade (e.g., amlodipine oedema treated with furosemide). Deprescribe with a plan: taper where needed, monitor for withdrawal or rebound, and set a review date.
Worked example
An 82-year-old taking oxybutynin 5 mg twice daily for urinary frequency, amitriptyline 25 mg at bedtime for sleep and neuropathic pain, zopiclone 7.5 mg nightly, ramipril and furosemide presents with new confusion and two falls.
- Reasoning: the combined anticholinergic and sedative burden (oxybutynin + amitriptyline + zopiclone) is the likely driver; furosemide adds orthostatic risk.
- Action: stop oxybutynin first (highest anticholinergic load, limited benefit at this age), taper amitriptyline, review the ongoing need for zopiclone, check blood pressure and electrolytes, discuss non-drug sleep and bladder strategies, document, and follow up in two weeks.
Traps that cost marks
- Adding a drug to treat an adverse effect instead of removing the culprit.
- Reporting an adverse reaction verbally but never documenting it or reporting to Canada Vigilance.
- Recommending that an interaction be "monitored" without naming the parameter or interval.
- Missing antimicrobial stewardship: asymptomatic bacteriuria is not an indication for antibiotics.