Also known as triarylmethane derivatives, this group of synthetic laxatives includes Phenolphthalein, bisacodyl, picosulfate and oxyphenisatin. The later two drugs are not available in the United States but are used in Europe. All of these drugs decrease glucose and electrolyte absorption in the small intestine; they may also evoke active secretion of ions into the intestinal lumen (Farak et al. 1985; Ewe 1987; de Witte et al. 1991) and alter intestinal motility (Leng-Peschlow 1986) mostly in the colon (Forth et al. 1966). The mechanisms of action are unclear for all these drugs because of conflicting data from different experimental preparations. Some results indicate increases in prostaglandins and cyclic nucleotides (Rachmilewitz et al. 1980; Autore et al. 1984; Farak and Nell 1984; Capasso et al. 1986) or changes in mucosal permeability (Saunders et al. 1975, 1977; Meisel et al. 1977). Others show inhibition of Na+, K+-ATPase (Donowitz and Welsh 1987). Their effects on motility are inconsistent and poorly characterized (Gullikson and Bass 1984). These laxatives, like castor oil and the anthraquinones, probably act through causing multiple changes in normal gut physiology. They usually do not act in less than 6 h after oral administration; therefore they are taken at bedtime to produce their effect the next morning.
KeywordsNitric Oxide Intestinal Motility Laxative Effect Mucosal Permeability Dioctyl Sodium Sulfosuccinate
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