16th May 2025

A 65-year-old gentleman presents to hospital with nausea, vomiting, abdominal pain, and palpitations.

A 65-year-old gentleman presents to hospital with nausea, vomiting, abdominal pain, and palpitations. His history is significant of asthma for which he was recently started on theophylline. His vital signs are blood pressure 140/78, heart rate 120/min, temperature 37C. His laboratory results are sodium 142 mmol/L, potassium 3.1 mmol/L, magnesium 1.1mmol/L and glucose 6.8 mmol/L. On physical examination he has an irregularly irregular pulse and his FEV1 is 55% of predicted. Which of the following is the most likely adverse effect of theophylline?

Select the SINGLE most appropriate option from the list below. Select ONE option only.