Which laxative is osmotic and commonly used for constipation?

• A. Macrogol
• B. Ispaghula husk
• C. Psyllium
• D. Glycerol

Answer: (A)

Osmotic laxatives work by drawing water into the bowel, increasing stool water content and softening the stool to promote safer, easier passage. Macrogol (polyethylene glycol) is a non-absorbable osmotic laxative that stays in the gut and pulls water into the lumen, leading to a soft, well-formed stool within a day or two. It is widely used for chronic constipation and for bowel cleansing because it is effective, well tolerated, and suitable for various patients, including children and those needing long-term help.

In contrast, ispaghula husk and psyllium are bulk-forming laxatives. They work by absorbing water to form a larger, softer stool mass, but they are not osmotic agents. They require adequate fluid intake and act by increasing stool bulk rather than pulling water into the stool.

Glycerol can act as an osmotic laxative when used rectally as glycerin suppositories or enemas for short-term relief, but it is not the common oral osmotic laxative used for routine constipation management. Macrogol remains the typical choice for widespread use.

So, the best answer is macrogol.