Pharmacology and Medication Safety
What to master
Anchor on the rights of administration (right patient, drug, dose, route, time, documentation, reason, response), two independent identifiers, and the concept of high-alert medications requiring independent double checks: insulin, heparin, opioids, chemotherapy, concentrated electrolytes, and neuromuscular blockers.
Know pharmacokinetics (absorption, distribution, metabolism, excretion) and how it shifts with age, liver and kidney function. Know the major interaction and antidote pairs: opioid → naloxone; benzodiazepine → flumazenil; heparin → protamine sulfate; warfarin → vitamin K (and fresh frozen plasma for major bleeding); paracetamol/acetaminophen overdose → N-acetylcysteine; digoxin → digoxin immune Fab; magnesium → calcium gluconate.
Know monitoring parameters: INR for warfarin, aPTT/anti-Xa for heparin, blood glucose and potassium with insulin, therapeutic drug levels for digoxin and vancomycin.
Traps in questions
- Look-alike/sound-alike names and trailing-zero or unit errors (mg vs mcg, units never abbreviated as "U").
- Questions where the ordered dose is wrong - you must calculate and question rather than administer.
- Confusing adverse effect with allergic reaction; a true allergy goes in the chart and the drug is withheld.
- Assuming a patient may take an oral medication while NPO or vomiting.
Worked example
Order: heparin infusion for a patient whose aPTT is 110 seconds (therapeutic range roughly 60–80) and who has new gum bleeding and haematuria. Options: continue the infusion, increase the rate, stop the infusion and notify the provider, give vitamin K. Choose stop the infusion and notify - this is over-anticoagulation with bleeding; protamine is the antidote if reversal is ordered.
Rule of thumb
Two identifiers, one calculation check, and an independent double check for every high-alert drug.