His antihypertensive medications should all be discontinued at present. He has significant and symptomatic orthostatic hypotension (all), AKI (bendroflumethiazide, perindopril) and hyponatraemia (bendroflumethiazide).
He needs antibiotic therapy for his UTI.
Trimethoprim would be the preferred agent, as it’s given twice daily and is better tolerated than nitrofurantoin (QDS).
Prescription of paracetamol for his pyrexia would also be appropriate, as would low dose prophylactic dalteparin.
In order to get some prescribing resources out there we intend to publish a series of prescribing problems on the website. The problems will appear at least weekly with the "answers" appearing a couple of days later. We'll use the standard exam stationery available on the LSE, but also available below in case you haven't got access to the LSE.