Alvimopan (LY246736, ADL 8-2698, trade name Entereg) is a potent, peripherally selective mu-opioid receptor antagonist. Alvimopan was developed by Adolor Corporation (now Cubist Pharmaceuticals) and GlaxoSmithKline for the treatment of postoperative ileus. Postoperative ileus is the impairment of gastrointestinal motility after intra-abdominal surgery or other non-abdominal surgeries. This may potentially delay gastrointestinal recovery and hospital discharge until its resolution. Morphine and other mu-opioid receptor agonists are universally used for the treatment of acute postsurgical pain; however, they are known to have an inhibitory effect on gastrointestinal motility and may prolong the duration of postoperative ileus. Following oral administration, alvimopan antagonizes the peripheral effects of opioids on gastrointestinal motility and secretion by competitively binding to gastrointestinal tract mu-opioid receptors.

Lubiprostone 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). Lubiprostone acts by specifically activating ClC-2 chloride channels, which is a normal constituent of the apical membrane of the human intestine, in a protein kinase A action independent fashion. Activation of ClC-2 chloride channels causes an efflux of chloride ions into the lumen, which in turn leads to an efflux of sodium ions through a paracellular pathway to maintain isoelectric neutrality. As a result, water follows sodium into the lumen in order to maintain isotonic equilibrium, thereby increasing intestinal fluid secretion. 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. Activation of ClC-2 chloride channels may also stimulate the recovery of muscosal barrier function by restoring tight junction protein complexes in the intestine. 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. Lubiprostone is marketed under the trade name Amitiza among others.

Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy. It is a disaccharide (double-sugar) formed from one molecule each of the simple sugars (monosaccharides) fructose and galactose. Lactulose is not normally present in raw milk but is a product of heat-processed: the greater the heat, the greater amount of this substance. Lactulose is not absorbed in the small intestine nor broken down by human enzymes, thus stays in the digestive bolus through most of its course, causing retention of water through osmosis leading to softer, easier to pass stool. It has a secondary laxative effect in the colon, where it is fermented by the gut flora, producing metabolites which have osmotic powers and peristalsis-stimulating effects (such as acetate), but also methane associated with flatulence. Lactulose is metabolized in the colon by bacterial flora to short chain fatty acids including lactic acid and acetic acid. These partially dissociate, acidifying the colonic contents (increasing the H+ concentration in the gut).[14] This favors the formation of the nonabsorbable NH+4 from NH3, trapping NH3 in the colon and effectively reducing plasma NH3 concentrations. Lactulose is used in the treatment of chronic constipation in patients of all ages as a long-term treatment. Lactulose is used for chronic idiopathic constipation, i.e. chronic constipation occurring without any identifiable cause. Lactulose may be used to counter the constipating effects of opioids, and in the symptomatic treatment of hemorrhoids as a stool softener.

Sorbitol is a polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures. Used as a non-stimulant laxative via an oral suspension or enema. Sorbitol exerts its laxative effect by drawing water into the large intestine, thereby stimulating bowel movements. Sorbitol plays a vital step in the 'polyol pathway'. The sudden injection of extra sorbitol can ruin the equilibrium of enzymes that regulate the conversion of glucose to fructose in a process associated with the onset of diabetes and its complications. Further, the polyol pathway is involved with a complex network of metabolic activities; disruption leads to a cascade of problems (citations here, here and here) such as mitochondrial failure, cell apoptosis (cell death), and DNA fragmentation. In general, sorbitol induces cell hyperosmotic stress resulting in phosphorylation (uptake of phosphorus into cell) — an important on/off switch regulating enzymes and signaling networks.

Sorbitol is a polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures. Used as a non-stimulant laxative via an oral suspension or enema. Sorbitol exerts its laxative effect by drawing water into the large intestine, thereby stimulating bowel movements. Sorbitol plays a vital step in the 'polyol pathway'. The sudden injection of extra sorbitol can ruin the equilibrium of enzymes that regulate the conversion of glucose to fructose in a process associated with the onset of diabetes and its complications. Further, the polyol pathway is involved with a complex network of metabolic activities; disruption leads to a cascade of problems (citations here, here and here) such as mitochondrial failure, cell apoptosis (cell death), and DNA fragmentation. In general, sorbitol induces cell hyperosmotic stress resulting in phosphorylation (uptake of phosphorus into cell) — an important on/off switch regulating enzymes and signaling networks.

Lactitol is a sugar alcohol. This ingredient has been determined to be GRAS for specified uses as a direct food additive and foods containing lactitol are eligible for a health claim related to dental caries. Lactitol is used as an oral powder or solution in the management of hepatic encephalopathy and in case of short-term treatment of occasional constipation. Intestinal flora of large intestine is metabolize lactitol to low-molecular organic acid, which leads to an increase in osmotic pressure in intestine, increase in volume of fecal masses bowel function normalization. This drug might cause abdominal discomfort, especially flatulence and abdominal pain rarely or sometimes abdominal distension. These effects tend to diminish or disappear after a few days of regular intake of the drug. Since 'antacids and neomycin can neutralize ' acidifying effect of lactitol on stool, they should not be co-administered with lactitol in cirrhotic patients with hepatic encephalopathy; however both substances do not alter the 'laxative effect in patients with constipation.

Glycerin (glycerol) is 3-carbon alcohol naturally occurring in the human body. It is the structural backbone triacylglycerol molecules, and can also be converted to a glycolytic substrate for subsequent metabolism. Glycerin is a colorless, odorless, viscous, sweet-tasting liquid. The FDA classifies glycerol as "generally recognized as safe". Glycerin is used in the pharmaceutical industry as a sweetener in syrups, lozenges, and as an excipient in eyewash solutions. As an individual prescription product, glycerin has uses as a hyperosmotic, osmotic diuretic, and ophthalmic agent. It may be used as an eye drop in the treatment of glaucoma to reduce intraocular pressure, as a solution or suppository for short-term treatment of constipation, to evacuate the bowel prior to a colonoscopy, and in some ocular surgeries. It may be given intravenously to reduce pressure inside the brain and used externally on the skin as a moisturizer. Glycerin has many other uses in the agricultural, food and pharmaceutical industry.

Oxyphenisatin is a stimulant laxative that has been used by mouth and as an enema. Oxyphenisatin was introduced as Lavema by Winthrop in US in 1959. Oxyphenisatin was used as a cleansing enema apart from x-ray studies and prior to urinary, gastro-intestinal and cholecystography x-ray examination. Oxyphenisatin was also used for preoperative preparation of the large intestine and colon. May be mixed with barium for x-ray examination of the large intestine. Oxyphenisatin may cause jaundice. Oxyphenisatin-induced liver damage usually occurs when the drug has been taken for at least six months and usually two years. Oxyphenisatin was withdrawn in most countries in the early 1970s.

Bisacodyl is typically prescribed for relief of constipation and for the management of neurogenic bowel dysfunction as well as part of bowel preparation before medical examinations, such as for a colonoscopy. Some drugs (e.g., diuretics, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, or non-steroidal anti-inflammatory drugs) increase risk due to fluid and electrolyte changes. Most common adverse reactions (> 3%) are overall discomfort, abdominal fullness, abdominal cramping, nausea, and vomiting.