Pharmacology
Pharmacology items test classification, mechanism, adverse effects, antidotes and dose calculation. For a nursing officer the practical angle dominates: which parameter to monitor, which drug to withhold, and how to compute a rate.
Antidote pairs
- Heparin to protamine sulphate; warfarin to vitamin K; opioid to naloxone; benzodiazepine to flumazenil; paracetamol to N-acetylcysteine; organophosphate to atropine plus pralidoxime; iron to desferrioxamine; methotrexate to leucovorin; magnesium to calcium gluconate.
Monitoring rules
- Digoxin: count the apical pulse for one minute and withhold if below 60/min in adults; toxicity causes nausea, yellow-green halos and bradycardia.
- Aminoglycosides: nephrotoxic and ototoxic; monitor creatinine and hearing.
- Vancomycin: infuse over at least 60 minutes to avoid red man syndrome.
- Rifampicin turns urine and tears orange and reduces oral contraceptive efficacy.
Worked example
Order: dopamine 5 µg/kg/min for a 70 kg patient, with 400 mg in 250 mL. Concentration is 400,000 µg ÷ 250 mL = 1600 µg/mL. Dose needed = 5 × 70 = 350 µg/min = 21,000 µg/hour. Rate = 21,000 ÷ 1600 = 13.1 mL/hour. Reasoning: convert everything to the same units before dividing, and always state the unit; an answer without mL/hour is incomplete.
High-alert precautions
Insulin and heparin need double checks and independent calculations; potassium ampoules are never given undiluted IV push; look-alike names such as dopamine and dobutamine need tall-man lettering.
Traps
Giving potassium chloride IV push, forgetting that many paediatric doses are mg/kg/day divided into 2–3 doses rather than per dose, and mixing milligrams with micrograms.