A 72-year-old woman presents with postural dizziness and recent falls. Her medications include ramipril, hydrochlorothiazide and bisoprolol for hypertension and heart failure. Standing blood pressure falls from 135/80 mmHg supine to 100/65 mmHg after 3 minutes with associated light-headedness. According to geriatric prescribing principles, what is the most appropriate next step?