Amitiza - General Information
Amitiza is a medication used in the management of idiopathic chronic constipation. It is a bicyclic fatty acid (prostaglandin E1 derivative) which acts by specifically activating ClC-2 chloride channels on the apical aspect of gastrointestinal epithelial cells, producing a chloride-rich fluid secretion. These secretions soften the stool, increase motility, and promote spontaneous bowel movements (SBM).
Pharmacology of Amitiza
Chronic idiopathic constipation is generally defined by infrequent or difficult passage of stool. The signs and symptoms associated with chronic idiopathic constipation (i.e., abdominal pain or discomfort, bloating, straining, and hard or lumpy stools) may be the result of abnormal colonic motility that can delay the transit of intestinal contents and impede the evacuation of rectal contents. One approach to the treatment of chronic idiopathic constipation is the secretion of fluid into the abdominal lumen through the activation of chloride channels in the apical membrane of the gastrointestinal epithelium. Amitiza is a locally acting chloride channel activator that enhances a chloride-rich intestinal fluid secretion without altering sodium and potassium concentrations in the serum.
Additional information about Amitiza
Amitiza Indication: For the treatment of chronic idiopathic constipation in the adult population.
Mechanism Of Action: Amitiza 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. By increasing intestinal fluid secretion, lubiprostone increases motility in the intestine, thereby increasing the passage of stool and alleviating symptoms associated with chronic idiopathic constipation. Patch clamp cell studies in human cell lines have indicated that the majority of the beneficial biological activity of lubiprostone and its metabolites is observed only on the apical (luminal) portion of the gastrointestinal epithelium.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Lubiprostone
Drug Category: Anti-constipation Agents
Drug Type: Small Molecule; Approved; Investigational
Other Brand Names containing Lubiprostone: Amitiza;
Absorption: Lubiprostone has low systemic availability following oral administration and concentrations of lubiprostone in plasma are below the level of quantitation (10 pg/mL).
Toxicity (Overdose): In a definitive Phase 1 cardiac repolarization study, 51 patients were administered a single oral dose of 144 mcg of lubiprostone, which is 6 times the normal single administration dose. Thirty-nine (39) of the 51 patients experienced an adverse event. The adverse events reported in >1% of this group included the following: nausea (45.1%), vomiting (27.5%), diarrhea (25.5%), dizziness (17.6%), loose or watery stools (13.7%), headache (11.8%), retching (7.8%), abdominal pain (5.9%), flushing or hot flush (5.9%), dyspnea (3.9%), pallor (3.9%), stomach discomfort (3.9%), syncope (3.9%), upper abdominal pain (2.0%), anorexia (2.0%), asthenia (2.0%), chest discomfort (2.0%), dry mouth (2.0%), hyperhidrosis (2.0%), skin irritation (2.0%) and vasovagal episode (2.0%).
Protein Binding: 94%
Biotransformation: The results of both human and animal studies indicate that lubiprostone is rapidly and extensively metabolized by 15-position reduction, α-chain β-oxidation, and ω-chain ω-oxidation. These biotransformations are not mediated by the hepatic cytochrome P450 system but rather appear to be mediated by the ubiquitously expressed carbonyl reductase. M3, a metabolite of lubiprostone in both humans and animals is formed by the reduction of the carbonyl group at the 15-hydroxy moiety that consists of both α-hydroxy and β-hydroxy epimers. M3 makes up less than 10% of the dose of radiolabeled lubiprostone.
Half Life: 0.9 to 1.4 hours
Dosage Forms of Amitiza: Not Available
Chemical IUPAC Name: 7-[(2R,4aR,5S,7aR)-2-(1,1-difluoropentyl)-2-hydroxy-6-oxo-3,4,4a,5,7,7a-hexahydrocyclopenta[e]pyran-5-yl]heptanoic acid
Chemical Formula: C20H32F2O5
Lubiprostone on Wikipedia: http://en.wikipedia.org/wiki/Lubiprostone
Organisms Affected: Humans and other mammals