BP106T • Unit 2Topic 3 of 3⏱ 5 Min Read

3. Protectives, Adsorbents & Saline Cathartics

💡 Core Concept & Clinical Context:

Protectives and Adsorbents are chemically inert, insoluble, fine inorganic powders administered orally to coat inflamed intestinal mucosa, form a protective barrier against irritants, and physically adsorb bacterial enterotoxins and toxic chemicals in diarrhea (e.g., Bismuth Subcarbonate, Light Kaolin / Hydrated Aluminum Silicate). Cathartics / Purgatives are agents that accelerate intestinal evacuation of feces. Saline (Osmotic) Cathartics are poorly absorbed hypertonic inorganic salts (e.g., Magnesium Sulphate / Epsom Salt, $MgSO_4\cdot 7H_2O$; Sodium Potassium Tartrate / Rochelle Salt) that retain water within the intestinal lumen via osmotic pressure, distending the bowel and stimulating reflex peristalsis.

Clinical Scenarios & Pharmacopoeial Examples:

1Mechanism of Saline Osmotic Cathartics

Epsom salt physiological mechanism.

Step-by-Step Breakdown:

•Oral Ingestion of Magnesium Sulphate (MgSO4.7H2O - Epsom Salt, 5-15 g):

•1. Mg2+ and SO4(2-) ions are poorly absorbed across intestinal mucosal epithelium.

•2. The hypertonic salt solution creates high osmotic pressure within the intestinal lumen.

•3. Water is drawn from blood and surrounding tissue fluids into the bowel lumen.

•4. The increased fluid volume distends the bowel wall, stimulating stretch mechanoreceptors.

•5. Reflex peristaltic contractions propel fluid intestinal contents, causing rapid watery evacuation within 1 to 3 hours.

📋Key Takeaways & Exam Highlights

Bismuth Subcarbonate: Insoluble protective that forms black bismuth sulfide ($Bi_2S_3$) in stools (harmless side effect).
Kaolin: Purified natural hydrated aluminum silicate [$Al_2Si_2O_5(OH)_4$]; highly porous adsorbent for diarrheal enterotoxins.
Rochelle Salt: Sodium Potassium Tartrate [$KOOC(CHOH)_2COONa\cdot 4H_2O$]; key ingredient in effervescent Seidlitz powder.

🇮🇳 हिन्दी व्याख्या (3. Protectives, Adsorbents & Saline Cathartics)

काओलिन (Kaolin) और बिस्मथ दस्त में आंतों पर सुरक्षा परत बनाकर बैक्टीरिया के जहर को सोख लेते हैं। मैग्नीशियम सल्फेट (एप्सम साल्ट) आंतों में पानी खींचकर पेट को तेजी से साफ (Cathartic) करता है।