NCT07569419 Proof of Principle Study for an Efficacy Trial of Linaclotide for Cystic Fibrosis

Eligibility & Interventions

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What to Expect as a Participant

You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.

Phase 1 is the earliest stage of human testing — safety and dosage are the primary focus. Visits are frequent and medical supervision is intensive. You will be among the first people to receive this treatment.

This trial targets 26 participants in total. It began in 2026-03-09 with a primary completion date of 2026-08.

Brief Summary

Linaclotide is a medicine used to treat constipation and irritable bowel syndrome with constipation (IBS-C). It works by acting on the surface of the gut lining, where it increases the movement of salt and water into the bowel. This softens stools, makes them easier to pass, and can also reduce gut pain One advantage of linaclotide is that, unlike some natural substances in the gut, it is stable and can act throughout the intestine. Studies in animals show that it has the strongest effect in the upper small intestine, but it may act in other parts of the bowel as well. In people, however, it is not yet clear whether linaclotide mainly works in the small intestine or in the large intestine (colon). Knowing this is important, because it could help the investigators understand whether linaclotide might also be useful in other conditions, such as cystic fibrosis, where the gut does not handle fluid properly. Linaclotide is taken as a capsule, but less than 1% is absorbed into the bloodstream. Instead, it stays in the gut, where it is broken down into smaller active parts. This means both the small intestine and colon may be exposed to its effects. Until now, it has been hard to study this because traditional methods only measure one part of the gut at a time. A team at the University of Nottingham has developed MRI scanning methods that can safely and non-invasively measure water content in the small intestine and colon. The aim of this pilot study is to use MRI in healthy volunteers to see exactly where linaclotide acts. This knowledge will help optimise future studies in conditions such as cystic fibrosis.

Eligibility Criteria

Inclusion Criteria: Participant is willing and able to give informed consent for participation in the study Not currently taking any medications (except for selective serotonin reuptake inhibitors, low dose tricyclic antidepressants, antihistamines, and oral contraceptive pill). Aged between 18-60 years. Ability to conform to the study protocol, including overnight fasting, dietary and lifestyle restriction, administering linaclotide and placebo intervention, MRI scanning, consuming the rice pudding/blue dye meal, and rating stool frequency and appearance. Exclusion Criteria: Contraindication to MRI scanning (i.e. metallic implants, pacemakers, history of metallic foreign body in eye(s) and penetrating eye injury, unable to lie flat and relatively still for less than 5 minutes.) Pregnancy, lactating, or planning pregnancy during the investigation declared by candidate. History declared by the candidate of pre-existing gastrointestinal disorder that may affect bowel function. Reported history of previous resection of the oesophagus, stomach, or intestine (excluding appendix). Intestinal stoma. Any medical condition that may potentially compromise participation in the study e.g., known food intolerance to rice pudding, known contraindication to the oral administration of linaclotide or placebo. Has a body mass index (BMI) value less than 18.5 or greater than 35. Will not agree to follow dietary and lifestyle restrictions required. Unable to stop drugs known to alter GI motility including mebeverine, opiates, monoamine oxidase inhibitors, phenothiazines, benzodiazepines, calcium channel antagonists for the duration of the study. Participants who are currently (or in the past 3 months) taking antibiotics or probiotics as these may impact GI function. Participation in night shift work the week prior to the study day. Night work is defined as working between midnight and 6.00 AM. Anyone who in the opinion of the investigator is unlikely to be able to comply with the protocol e.g., cognitive dysfunction, chaotic lifestyle related to substance abuse. Having taken part in a research study in the last 3 months involving invasive procedures or an inconvenience allowance \-

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