MRCP2-0032

MRCP2-0032

A 65-year-old retired teacher presents with lightheadedness and a medical history of depression, osteoarthritis, and sciatica. She is currently taking codeine, ibuprofen, pregabalin, amitriptyline, and nitrofurantoin for recurrent urinary tract infections. An ECG shows normal sinus rhythm with a heart rate of 80 bpm, no dynamic ST/T changes, a PR interval of 140ms, and a prolonged QTc of 526ms. Which medication is most likely responsible for her symptoms?