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Asimadoline is an orally active, peripherally restricted kappa-opioid receptor agonist that was investigated for irritable bowel syndrome (IBS), mainly the diarrhea-predominant subtype, and for other conditions involving visceral pain.
- Improved adequate relief of pain/discomfort in diarrhea-predominant IBS patients with at least moderate baseline pain
- Reduced sensitivity to colonic distension (a marker of visceral pain) in controlled studies
- Peripheral action limits classic central opioid side effects
- Missed its primary endpoint in the broader intent-to-treat trial population
- Never completed Phase 3 development or received approval
Overview
It never reached market; it showed a real signal in patients with at least moderate baseline pain but didn't clear the bar across the whole trial population.
Mechanism
Asimadoline selectively activates kappa-opioid receptors located outside the central nervous system, particularly in the gut. Because it does not readily cross the , it can modulate visceral pain and bowel sensitivity through peripheral opioid signaling while largely avoiding central opioid effects such as sedation or euphoria.
receptor fingerprint
Kappa-opioid receptor (KOR)Agonist
Safetyrisks and cautions, not medical advice
In Phase 2 and Phase 3 trials for IBS, asimadoline was generally well tolerated at doses up to 1.0 mg twice daily, with adverse events comparable to placebo in most reports. Because it acts peripherally, it appears to carry a lower risk of the central effects and dependence potential associated with classic opioids, though it never completed the full regulatory safety review required for approval.
Subjective profileweighing the evidence above
Never proved itself. It helped the subgroup with genuinely painful diarrhea-predominant IBS but missed its primary endpoint in the broader population and never finished Phase 3, so there is no approval and no long-term safety record behind it. A smart piece of design, and no reason to chase it.
Resources
No suppliers are provided for compounds like this. This entry is here for reference.
Research
- 2004first citedEffect of asimadoline, a kappa opioid agonist, on pain induced by colonic distension in patient…
- 2010most recentAsimadoline in the treatment of irritable bowel syndrome
- 1.Novel pharmacology: asimadoline, a kappa-opioid agonist, and visceral sensation
- 2.Effect of asimadoline, a kappa opioid agonist, on pain induced by colonic distension in patients with irritable bowel syndrome
- 3.Asimadoline in the treatment of irritable bowel syndrome
3 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
What is Asimadoline used for?
It was studied as a treatment for irritable bowel syndrome, particularly the diarrhea-predominant subtype with moderate to severe pain.
How does Asimadoline work?
It activates kappa-opioid receptors outside the brain and spinal cord, mainly in the gut, to dial down pain signals and abnormal bowel sensitivity without typical opioid brain effects.
Is Asimadoline well-researched?
It went through Phase 2 and into Phase 3 trials for IBS with published results, but it was never approved and development appears to have stalled.
Limitations of the evidence
- Long-term safety outside trial settings is not established
Adverse effects
- Missed its primary endpoint in the broader intent-to-treat trial population
- Never completed Phase 3 development or received approval