Constipation-predominant irritable bowel syndrome: A review of current and emerging drug therapies

Table 1 Main types of pharmacologic laxatives

Type	Agents	Mechanism of action	Most common adverse events
Bulking agents	Psyllium	Increase in stool bulk and reduction in consistency by luminal water binding	Bloating
	Methylcellulose		Flatulence
	Calcium polycarbophil
Stool softeners	Docusate potassium	Softening and lubrication of stools by increasing water secretion	Nausea
(surfactants)	Docusate sodium		Vomiting
	Docusate calcium		Abdominal pain/cramps
			Rectal urgency
Osmotic laxatives	Milk of Magnesia (magnesium hydroxide)	Osmotic water retention, decreased stool consistency, and increase fecal volume and peristalsis	Sweet taste
	Magnesium citrate		Nausea
	Magnesium sulphate		Bloating
	Sodium picosulphate/magnesium citrate (Picoprep®)		Flatulence
	Lactulose/lactilol		Abdominal pain/cramps
	Sorbitol		Electrolyte disturbances (?)
	Polyethylene glycol (macrogol)
Stimulant laxatives	Anthraquinones	Luminal water retention through activation of CAMP, and induction of colonic contractions by acting on enteric nerves	Abdominal pain/cramps
	Senna		Dehydration
	Cascara		Electrolyte disturbances
	Bisacodyl		Muscle cramps
	Phenolphthalein		Melanosis coli/colonic inertia (?)

CAMP: Cyclic adenosine monophosphate.