Pharmacology and Medication Administration
Pharmacology and Medication Administration tests safe prescribing support, calculation accuracy, monitoring for effect and toxicity, and patient education. Egyptian practice is regulated through the Egyptian Drug Authority, so know both the science and the local rules on controlled drugs, prescription writing and adverse reaction reporting.
Core principles
Pharmacokinetics covers absorption, distribution, metabolism (mostly hepatic CYP450) and excretion (mostly renal) - renal impairment requires dose adjustment. Pharmacodynamics covers agonists, antagonists and the therapeutic index. A narrow therapeutic index (digoxin, lithium, warfarin, phenytoin, aminoglycosides) demands level monitoring.
The rights and high-alert medications
Right patient by two identifiers, drug, dose, route, time, documentation, reason, and the right to refuse. High-alert drugs - insulin, heparin, chemotherapy, concentrated potassium and opioids - need independent double-checks, standard concentrations and clear labelling. Never give undiluted potassium chloride by IV push.
Calculations: dimensional analysis
Dose required equals (desired ÷ have) × quantity. Check units first: mg to mcg is multiplied by 1000. For weight-based doses, calculate mg/kg then convert to mL. Always cross-check that the answer is plausible; a 10 mL answer for an order of 0.5 mL signals an error.
Drug classes and monitoring
- Aminoglycosides (gentamicin): nephrotoxic and ototoxic; monitor creatinine and levels.
- Vancomycin: nephrotoxic; monitor trough and infusion rate, since rapid infusion causes red man syndrome.
- Warfarin: monitor INR, usually target 2–3; vitamin K is the antidote; many interactions.
- Heparin: monitor APTT or anti-Xa; protamine sulphate reverses it; watch for heparin-induced thrombocytopenia.
- Insulin: know onset and peak; hypoglycaemia is the main risk. Rapid-acting insulin is given with meals, long-acting once daily.
- Digoxin: check the pulse before giving and withhold if below 60/min in adults; toxicity causes nausea, visual changes and bradycardia.
- Opioids: respiratory depression; naloxone reverses it.
- Corticosteroids: give with food, monitor glucose and never stop abruptly.
Worked example
A child weighing 12 kg is prescribed amoxicillin 15 mg/kg/dose three times daily. Stock is 125 mg/5 mL. What volume do you give? Reasoning: dose equals 15 × 12 = 180 mg per dose. Volume equals (180 ÷ 125) × 5 = 1.44 × 5 = 7.2 mL. Checks: the volume is plausible for a 12 kg child; confirm the maximum daily dose is not exceeded; a second nurse verifies; document the dose and time.
Traps that cost marks
- Decimal-point slips and missed unit conversions.
- Using a 10 mL syringe for 0.3 mL, or a 1 mL syringe for a large volume.
- Withholding a drug without documenting the reason.
- Failing to report an adverse drug reaction to the national pharmacovigilance system.