The molecular switch that allows people to feel the heat of chilli peppers is a promising new target for drugs against irritable bowel syndrome, British researchers said on Tuesday.

They found people with the common and painful bowel problem had higher than usual levels of the pain receptor TRPV1 responsible for the burning sensation associated with chilli.

“What we found is that in people with irritable bowel syndrome there seem to be more nerve fibres expressing the chilli pepper receptor,” said Subrata Ghosh, a gastroenterologist at Imperial College London, who co-led the study.

“It would mean compared to a healthy person these patients may be more sensitive to triggers like chilli peppers.”

Irritable bowel syndrome affects the large intestine and causes a host of problems including bloating, abdominal cramping, diarrhoea and constipation. About 20 percent of adults suffer from the condition, Ghosh said.

One problem, however, is that widespread treatments are not available, he added.

Novartis AG pulled its drug Zelnorm from shelves last year after clinical trial data suggested a possible heart risk, and the medicine is now reserved for use only in patients whose condition is life-threatening or requires hospitalisation.

PULLED FROM THE MARKET

GlaxoSmithKline Plc’s Lotronex was also pulled from the U.S. market in 2000 after some patients experienced severe intestinal problems. U.S. health regulators allowed it to return two years later with restrictions on its use and the medicine is now sold by privately-held Prometheus Laboratories Inc.

The U.S. Food and Drug Administration in April approved Amitiza, the first U.S. drug to treat irritable bowel syndrome with constipation (IBS-C) in adult women, a medicine marketed by Takeda Pharmaceutical Co and its developer, Sucampo Pharmaceuticals Inc.

The laxative known by the generic name lubiprostone was approved for use by women over 18 years old, but not for men, because its effectiveness was not conclusively demonstrated, the FDA said.

Ghosh also said there was plenty of research into blocking the TRPV1 receptor as a way to treat other diseases.

And the latest findings mean that with some 50 pharmaceutical companies worldwide - including Glaxo - developing drugs targeting the receptor for other conditions, irritable bowel syndrome is now also a candidate.

“Many drug companies ... are focusing on making drugs that focus on blocking this particular receptor,” he said in a telephone interview.

The researchers discovered the difference in the levels of nerve fibres controlling the pain receptor after comparing biopsies of colon tissue taken from 23 people with the condition and 22 healthy volunteers.

Their findings may help to explain why people with irritable bowel syndrome often feel worse after eating spicy food and suggest that the presence of more of these nerve fibres make people with the condition more sensitive to pain, Ghosh said.

By Michael Kahn
LONDON (Reuters)