Bulk-forming laxative
- Non-absorbable fiber absorbs water → increases stool bulk
- Bulk stretches the colon wall → stimulates peristalsis
- Requires adequate water; otherwise the added bulk can obstruct
- ⚑ Avoid with clozapine — additive risk of bowel obstruction
Drugs with this mechanism (6)
- Acacia gum — Soluble prebiotic fiber used in dietary supplements; also a pharmaceutical thickener and stabilizer.
- Calcium polycarbophil — Nonfermentable bulk-forming fiber that can normalize either hard or loose stool.
- Inulin — Fermentable prebiotic fiber; can improve bowel regularity, but gas and bloating commonly limit tolerance.
- Methylcellulose — Nonfermentable bulk-forming fiber for constipation; usually causes less gas than psyllium.
- Psyllium — Soluble fiber; needs fluid or it obstructs.
- Wheat dextrin — Soluble fiber supplement; fermentation can cause gas and bloating.
Self-check
- Why must bulk-forming laxatives be taken with adequate water?
Otherwise the added bulk can obstruct. - Which named drug makes added bulk an obstruction concern in this source?
Clozapine.
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