A 59-year-old man with type 2 diabetes and hypertension has an eGFR of 45 mL/min/1.73 m² and urine albumin-to-creatinine ratio of 80 mg/mmol. His blood pressure is 146/88 mm Hg on amlodipine alone. According to Canadian kidney and hypertension guidelines, what is the most appropriate next step?