Pharmacology and Medication Safety
This domain tests safe administration and monitoring, not drug trivia. Expect dose calculations, high-alert drug safeguards, and recognition of the adverse effects of the medicines most used in Mongolia, including tuberculosis regimens and anticoagulants.
Core rules
- Rights of administration: right patient, drug, dose, route, time and documentation, plus the right to refuse and the right reason.
- High-alert medicines: insulin, heparin, concentrated potassium chloride, opioids and chemotherapy. Potassium concentrate is never given IV push undiluted.
- Calculation: volume to give = (dose ordered / stock strength) x stock volume. Always sanity-check the answer against the vial size and the maximum dose.
- TB drugs: isoniazid causes peripheral neuropathy (prevented with pyridoxine) and hepatitis; rifampicin turns secretions orange and induces cytochrome P450, reducing oral contraceptive efficacy; ethambutol causes optic neuritis with colour-vision change; pyrazinamide raises urate.
- Digoxin therapeutic range is about 0.5-2 ng/mL; toxicity shows as nausea, visual halos and bradycardia, and hypokalaemia predisposes to it.
- Warfarin is monitored by INR, usually targeting 2-3; vitamin K is the antidote.
Worked example
A 15 kg child is prescribed amoxicillin 40 mg/kg/day in two divided doses; the suspension is 250 mg/5 mL. Reasoning: 40 x 15 = 600 mg per day, so 300 mg per dose. Volume = (300 / 250) x 5 = 6 mL per dose. Check that 300 mg is below the maximum single dose, then measure with an oral syringe rather than a spoon, and record the weight used for the calculation.
Traps
Decimal slips between mg and micrograms; giving potassium as a bolus; assuming rifampicin can be combined with any antiretroviral without review; missing that a patient's own herbal or traditional medicine can interact; not checking the weight on the chart is current.