This causes the affected portion of the colon to be unable to contract and relax to help push out a bowel movement. The affected portion of the colon remains contracted, making it difficult for stool to pass through. Concern for HD should be raised in a child who has not passed stool during the first 48 hours of life. Milder forms of HD, in which only a small portion of the colon is affected, can present later in childhood as constipation, abdominal pain, and bloating. Similar disorders to HD include anal achalasia and hypoganglionosis. In hypoganglionosis, there is a low number of neural crest cells, so the colon remains contracted. In anal achalasia, the internal anal sphincter remains contracted, making it difficult for stool to pass. However, there is a normal number of neural crest cells present.There are also congenital structural anomalies that can lead to constipation, including anterior displacement of the anus, imperforate anus, strictures, and small left colon syndrome. Anterior displacement of the anus can be diagnosed on physical exam. The disease causes constipation because the inappropriate positioning of the anus which make it difficult to pass a bowel movement. Imperforate anus is an anus that ends in a blind pouch and does not connect to the rest of the persons intestines. Small left colon syndrome is a rare disease in which the left side of the babies colon has a small diameter, which makes it difficult for stool to pass.
This disruption to the electrochemical gradient is in part rectified by the passive secretion of positively charged sodium ions in to the lumen and water follows by osmosis.Plecanatide is also known to have an anti-nociceptive effect in animal models, however the exact mechanism of action is not yet fully elucidated. It has been suggested that this may be in part to the anti-inflammatory action of guanylate cyclase-C by its inhibition of pro-inflammatory cytokines, or through the inhibition of associated sensory neurons. Pharmacokinetics and metabolism
As plecanatide acts on receptors present on the apical side of endothelial cells lining the gastrointestinal tract it is able to impart its effect without ever entering circulation. As with most orally ingested peptides, plecanatide is degraded by intestinal enzymes, and so very little of the active drug enters systemic circulation. Minimal amounts of the drug are expected to be transported in to the body, and concentrations of plecanatide and its metabolites are undetectable in plasma following the recommended dosage of 3 mg. It has also been shown that dosages up to 48.6 mg produced no detectable concentration of plecanatide in human plasma at any time point after ingestion. References
External links
"Plecanatide". Drug Information Portal. U.S. National Library of Medicine.