Osmotic laxative

Osmotic laxative is not a specific molecular target but rather a class of pharmacological agents used to treat constipation. These substances are poorly absorbed in the intestine and act by drawing water into the bowel lumen via osmosis. This increased water content softens stool and stimulates peristalsis to promote defecation. Common examples include polyethylene glycol (PEG), lactulose, magnesium hydroxide ("milk of magnesia"), sorbitol, glycerin suppositories, and magnesium citrate. Some osmotic laxatives have additional uses; for example, lactulose is also used to lower blood ammonia levels in hepatic encephalopathy. While generally safe when used as directed for short periods, overuse can lead to dehydration or electrolyte imbalances—particularly with saline-based products like those containing magnesium or phosphate ions. Osmotic laxatives are available over-the-counter in various formulations including powders for solution and oral liquids[1][3][4][5]. Note on classification error: "Osmotic laxative" refers to a drug class/mechanism—not a single molecule/receptor/therapeutic target—so it does not fit structured data fields intended for molecular targets such as receptors or enzymes.

Other names

Osmotic laxativesosmotic agent (laxative)PEG (for polyethylene glycol)Milk of Magnesia (for magnesium hydroxide)LactuloseSorbitolMagnesium citrateGlycerin suppositories

Draws water into the intestinal lumen by osmosis to soften stool and promote bowel movements[1][4][5] Some agents (e.g., lactulose) also reduce ammonia absorption in hepatic encephalopathy by promoting bacterial uptake of ammonia in the colon[4]