A 68-year-old man is commenced on ramipril for hypertension. A week later, his routine blood tests show: Sodium 138 mmol/L, Potassium 5.8 mmol/L, Urea 8.2 mmol/L, Creatinine 130 µmol/L (baseline creatinine was 100 µmol/L). What is the most appropriate action regarding his ramipril?