Hyperkalaemia in an elderly patient with chronic heart failure and renal impairment

A 74-year-old man presents to the emergency department with two days of nausea, weakness and reduced appetite. He has chronic heart failure with reduced ejection fraction and stage 3 chronic kidney disease. On examination, he is alert but drowsy, heart rate is 44 bpm and irregular, blood pressure 118/72 mmHg, respiratory rate 16/min, oxygen saturation 97% on room air, temperature 36.8 °C. He has mild pulmonary oedema at the lung bases and no peripheral oedema. ECG shows sinus bradycardia with short PR interval and tall, peaked T waves in the precordial leads, with a QRS duration of 120 ms. Blood tests: serum potassium 6.3 mmol/L (reference range 3.5-5.0), serum creatinine 1.6 mg/dL, estimated glomerular filtration rate (eGFR) 38 mL/min/1.73 m², urea 18 mmol/L, glucose 5.2 mmol/L, bicarbonate 20 mmol/L. His regular medicines include ramipril, spironolactone, furosemide, bisoprolol and aspirin. He has no known drug allergies. You are the on-call doctor. Write the immediate management prescriptions for this patient's hyperkalaemia and state which of his regular medicines should be withheld.