Pharmacology and Pharmacotherapy
Core concepts
Build a receptor-and-mechanism map: agonists/antagonists (competitive vs noncompetitive), partial agonists, inverse agonists, and the distinction between affinity and efficacy. Know the major autonomic transmitters and the effects of sympathetic vs parasympathetic activation, then attach drug classes to them. Understand pharmacokinetic parameters (volume of distribution, clearance, half-life, first-pass effect) and how they change with hepatic or renal impairment. Pharmacodynamics covers dose–response, therapeutic index, tolerance, and idiosyncrasy.
Therapeutics
Be able to select first-line therapy for common conditions: hypertension, type 2 diabetes, asthma/COPD, infection, pain, and anticoagulation. Know key adverse effects and contraindications (e.g., ACE-inhibitor cough and hyperkalemia; beta-blocker caution in asthma; NSAID renal and GI risk; aminoglycoside nephro/ototoxicity; statin myopathy). Recognize clinically important interactions (CYP inhibition/induction, warfarin, MAO inhibitors, QT prolongation).
Traps in questions
- Confusing half-life (time for concentration to halve) with duration of action.
- Assuming a drug with a large volume of distribution is removed quickly by dialysis (it usually is not).
- Mixing up competitive antagonism (surmountable by more agonist) with noncompetitive (not surmountable).
- Missing renal dose adjustment questions when creatinine clearance is given.
Worked example (rule of thumb)
Steady state is reached after roughly 4–5 half-lives. A drug with t½ = 8 h reaches steady state in about 32–40 h; a loading dose is used when you cannot wait that long. Use this rule whenever a question asks about time to steady state or time to washout.