Sam is a 33 year old solicitor who is known to have Irritable bowel syndrome and has been struggling with abdominal cramps despite using various antispasmodic drugs and peppermint oil capsules. Paracetamol has little effect. He used to have predominant diarrhoea symptoms, but these are controlled well with changes to his diet. There is no rectal bleeding, weight loss or recent change in his bowel habit.
Which of the below mediations is recommended off-label by NICE to manage pain associated with Irritable bowel syndrome?