A 69 year old man attends the GP clinic. Over the past week, he has developed a sudden onset of severe pain, swelling and redness affecting his right first metatarsophalangeal joint, making it difficult to walk. During the consultation, he also reports a 2-day history of dysuria, urinary frequency and urgency, with no fever or loin pain. PMH. Heart failure with reduced ejection fraction, hypertension, atrial fibrillation, previous myocardial infarction, rheumatoid arthritis, hypercholesterolaemia. DH. His regular medicines are listed below. SH. Ex-smoker. Drinks approximately 12 units of alcohol per week.

On examination
Appears comfortable at rest. HR 64 beats/min (regular), BP 116/72 mmHg, RR 16 breaths/min, oxygen saturation 97% on air. His right first metatarsophalangeal joint is erythematous, swollen, warm and exquisitely tender on palpation.

Investigations
Sodium 139 mmol/L (137-144)
Potassium 4.4 mmol/L (3.5-5.3)
Urea 5.8 mmol/L (2.5-7.0)
Creatinine 89 micromol/L (60-110)
eGFR 72 mL/min/1.73 m²
Serum urate 525 micromol/L (155-357)

Urine dipstick shows leucocytes and nitrites positive. Polarised microscopy of synovial fluid confirms monosodium urate crystals.

Question A
Select THREE prescriptions that most likely may have contributed to his presenting complaint.

Question B
Select ONE prescription that should be avoided with trimethoprim because of the risk of a serious drug interaction.