NZREX Pharmacology & Prescribing 2

Question 1

A patient on lithium for bipolar disorder presents with coarse tremor, confusion, and vomiting. His serum lithium level is 2.3 mmol/L. What is the most appropriate immediate management?

Accepted Answer

Cease lithium immediately and consider haemodialysis

Answer

A lithium level above 2.0 mmol/L with clinical symptoms represents severe toxicity requiring immediate cessation; haemodialysis is indicated to rapidly remove lithium when toxicity is severe or the patient is deteriorating.

Question 2

A patient with rheumatoid arthritis is commenced on weekly oral methotrexate. Which supplement must be co-prescribed to reduce the risk of mucositis and haematological side effects?

Accepted Answer

Folic acid

Answer

Folic acid supplementation is co-prescribed with methotrexate because methotrexate inhibits dihydrofolate reductase; folic acid reduces mucositis, bone marrow suppression, and hepatotoxicity without significantly impairing efficacy.

Question 3

Which antibiotic class is generally contraindicated in children under 12 years due to the risk of arthropathy and potential damage to developing cartilage?

Accepted Answer

Fluoroquinolones (e.g., ciprofloxacin)

Answer

Fluoroquinolones are contraindicated in children under 12 (and generally under 18 in most guidelines) due to evidence of arthropathy and cartilage toxicity demonstrated in animal studies and paediatric case reports.

Question 4

A patient taking ramipril (ACE inhibitor) is commenced on spironolactone (a potassium-sparing diuretic). Which electrolyte imbalance must be closely monitored?

Accepted Answer

Hyperkalaemia

Answer

Both ACE inhibitors (which reduce aldosterone-mediated potassium excretion) and potassium-sparing diuretics retain potassium, creating a significant risk of dangerous hyperkalaemia when combined.

Question 5

A patient with type 2 diabetes has a new eGFR of 25 mL/min/1.73m². What change should be made to their metformin therapy?

Accepted Answer

Cease metformin as it is contraindicated at this eGFR

Answer

Metformin is contraindicated when eGFR falls below 30 mL/min/1.73m² due to impaired renal excretion leading to drug accumulation and the risk of potentially fatal lactic acidosis.

NZREX Practice Test

NZREX Practice Test

NZREX Pharmacology & Prescribing 2