MRCP2-0902

A 68-year-old man with a history of chronic obstructive pulmonary disease presents to the Emergency department with an exacerbation. His GP prescribed ciprofloxacin three days ago. He is also taking high dose salmeterol fluticasone, oral theophylline, and tiotropium. He has been experiencing vomiting and dizziness for the past 24 hours. His blood pressure is 132/88 mmHg with a postural drop of 15 mmHg, and his serum potassium level is 3.0 mmol/l.

What is the most appropriate course of action?