What is the mechanism of action of lubiprostone (Amitiza) on CIC-2 (chloride channel 2)?

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From the Guidelines

Lubiprostone activates the CIC-2 chloride channel. This medication works by increasing chloride secretion into the intestinal lumen, which leads to increased intestinal fluid secretion and enhanced intestinal motility 1. When lubiprostone activates CIC-2 channels, the resulting increase in fluid in the intestinal lumen softens stool and accelerates intestinal transit time.

Key Points

  • Lubiprostone is typically prescribed for chronic idiopathic constipation and irritable bowel syndrome with constipation (IBS-C) at doses of 8-24 mcg twice daily 1.
  • The medication is a prostaglandin E1 derivative that specifically targets CIC-2 chloride channels without significant systemic absorption, which helps minimize side effects 1.
  • Common side effects include nausea, which is dose-dependent and can be mitigated by taking the medication with food and water 1.
  • The medication's mechanism of action through CIC-2 activation represents a targeted approach to treating constipation by addressing the underlying fluid secretion issues in the intestine rather than simply stimulating motility.

Important Considerations

  • Individuals with moderate or severe hepatic insufficiency should receive a lower dose of lubiprostone (ie, 8μg twice daily) 1.
  • The medication is contraindicated in individuals with known or suspected mechanical GI obstruction 1.

From the FDA Drug Label

Lubiprostone is a locally acting chloride channel activator that enhances a chloride-rich intestinal fluid secretion without altering sodium and potassium concentrations in the serum. Lubiprostone acts by specifically activating ClC-2, which is a normal constituent of the apical membrane of the human intestine, in a protein kinase A–independent fashion Lubiprostone activates ClC-2 2

From the Research

CIC-2 Activation by Lubiprostone

  • Lubiprostone activates the type 2 chloride channel (CIC-2) in the apical membrane of the gastrointestinal epithelium, resulting in increased fluid secretion 3, 4.
  • The activation of CIC-2 by lubiprostone leads to relief of constipation by increasing chloride and fluid secretion into the intestines 4, 5.
  • Studies have shown that lubiprostone improves the number of bowel movements, stool consistency, and global assessment of constipation compared to placebo 3, 4, 6.

Mechanism of Action

  • Lubiprostone's mechanism of action involves the activation of CIC-2, which increases chloride and water secretion in the intestines 6, 7.
  • The increased fluid secretion softens the stool and promotes bowel movements, providing relief from constipation 3, 4.

Clinical Efficacy

  • Clinical trials have demonstrated the efficacy of lubiprostone in treating chronic idiopathic constipation, with significant improvements in spontaneous bowel movements and stool consistency 3, 4, 6.
  • Lubiprostone has also been shown to be effective in treating opioid-induced constipation and irritable bowel syndrome with constipation 6.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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