Chronic constipation and IBS-C are two of the most common functional bowel disorders encountered by primary care providers and gastroenterologists, affecting up to 27% of the population in Western countries.
The treatment of these disorders is often empiric [whatever is found to be effective] and most current therapies are indicated for episodic constipation. Over time, most patients become refractory [resistant] to one or more laxatives.
Lubiprostone (Amitiza) has been approved by the US Food and Drug Administration (FDA) for the treatment of chronic-idiopathic constipation. It is an oral bicyclic fatty acid that selectively activates type 2 chloride channels in the apical membrane of the intestinal epithelial cells, hence stimulating chloride secretion, along with passive secretion of sodium and water, inducing peristalsis and laxation [loosening and movement], without stimulating gastrointestinal smooth muscle.
Several trials have shown it to be effective in the treatment of chronic idiopathic constipation, and recently also IBS-C.
It has little systemic absorption [confined within gut] and is almost free of any serious adverse effects. However, occasionally can cause nausea.
Based on the available evidence, it is reasonable to conclude that lubiprostone should be added to the short list of evidence-based pharmacotherapies for chronic constipation and IBS-C.
Given the overlap between chronic constipation and IBS-C, clinicians can consider two strategies when deciding on the initial dose of lubiprostone. Based on current product labeling, it is recommended that:
• 8 micrograms twice daily be started in patients with IBS-C, whereas
• 24 micrograms twice daily be used in those with chronic constipation.
Thus far, lubiprostone offers a novel approach to our therapeutic armamentarium.
However, there is a need for more drugs with different mechanisms of action, in order to treat constipation that is often multifunctional [involving multiple factors].
Source: Digestive Diseases and Sciences, Apr 27, 2011. PMID: 21523369, by Schey R, Rao SS. Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA. [Email: firstname.lastname@example.org]