A drug that costs just 25p a day can transform the lives of millions of people with irritable bowel syndrome, research has found.
Amitriptyline was found to significantly improve the symptoms of this debilitating disease, which affects up to 13 million Britons and 30 million Americans.
Experts said low doses of antidepressants, used to treat a variety of conditions from nerve pain to migraine prevention, should also be prescribed for irritable bowel syndrome (IBS).
In the first trial of its kind, British researchers wanted to test whether low doses of the antidepressant could benefit IBS patients in a community setting.
Amitriptyline, pictured, made people twice as likely to report an overall improvement in IBS symptoms after six months than those taking dummy medications.
Some 463 patients were recruited from 55 general practices in West Yorkshire, Wessex and the west of England, half were given amitriptyline and the other half a placebo.
Patients controlled how many tablets of the trial medication they took based on a score determined by their IBS symptoms and any side effects experienced.
Those taking amitriptyline were almost twice as likely to report an overall improvement in IBS symptoms after six months than those taking dummy medications.
Researchers from the universities of Leeds, Southampton and Bristol also monitored participants’ anxiety or depression scores.
They found that these were not altered, suggesting that the beneficial effects of the drug occurred through the intestine, not due to any antidepressant effect.
IBS, which affects approximately one in 20 people worldwide, causes excruciating pain, bloating, diarrhea and constipation, and there are few effective treatments available.
This long-term disease, which has no known cure, can have a substantial impact on sufferers’ quality of life and ability to work and socialize.
Amitriptyline belongs to a group of medications called tricyclics, which were originally used in high doses to treat depression.
But the medication is also believed to act directly on the nerves in the intestine, which has an effect on digestive discomfort.
Compounds called neurotransmitters are also present in the nerves of the digestive system, which are found in the brain and are responsible for regulating mood.
Previous small trials of low-dose tricyclic antidepressants for IBS suggested a possible benefit in patients seen in hospital-based clinics, who often have more difficult-to-treat symptoms.
But this new study, published in The Lancet, is the first to study its use for IBS in primary care.
NICE guidance states that antidepressants can be used to treat the condition if other options have failed, but doctors are often reluctant.
The researchers hope the findings will prove reassuring to GPs, along with new suggested dosing guidelines.
Alexander Ford, Professor of Gastroenterology at the University of Leeds School of Medicine, said: “Amitriptyline is an effective treatment for IBS and is safe and well tolerated.
IBS affects approximately one in 20 people worldwide and does not have many treatments available
“This rigorously conducted new research indicates that general practitioners should help primary care patients try low-dose amitriptyline if their IBS symptoms have not improved with recommended first-line treatments.”
Professor Andrew Farmer, from the National Institute of Health and Care Research, said: “The results of this study are hugely encouraging.
“This shows that a drug that is already widely available to treat other diseases appears to be safe and effective for people with IBS.”
