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

2. Electrolyte Replacement Therapy: ORS (WHO/IP Standard) & IV Fluids

💡 Core Concept & Clinical Context:

Acute dehydrating diarrhea (cholera, rotavirus gastroenteritis) causes life-threatening loss of water and electrolytes. Oral Rehydration Therapy (ORT) exploits the Sodium-Glucose Cotransport (SGLT-1) mechanism in small intestinal enterocytes: sodium is actively co-transported with glucose across mucosal brush borders even in severe cholera toxin diarrhea, dragging water molecules along by osmotic gradients. The World Health Organization (WHO) and Indian Pharmacopoeia (IP) prescribe the Reduced Osmolarity ORS Formulation.

Clinical Scenarios & Pharmacopoeial Examples:

1Official WHO / IP Reduced Osmolarity ORS Formulation (Per 1.0 Liter)

Precise stoichiometric quantities and osmolarity breakdown.

Step-by-Step Breakdown:

•Composition of 1 Liter ORS Solution:

•1. Sodium Chloride (NaCl): 2.60 g (Provides Na+ and Cl-)

•2. Potassium Chloride (KCl): 1.50 g (Replaces intracellular K+ lost in stool)

•3. Trisodium Citrate Dihydrate (C6H5Na3O7.2H2O): 2.90 g (Replaces bicarbonate and corrects metabolic acidosis)

•4. Anhydrous Dextrose / Glucose (C6H12O6): 13.50 g (Drives active SGLT-1 cotransport)

•Total Powder Weight per Sachet = 20.50 g dissolved in exactly 1.0 Liter of potable water.

•Ionic Concentration (mEq/L or mmol/L):

•• Sodium (Na+): 75 mEq/L

•• Chloride (Cl-): 65 mEq/L

•• Potassium (K+): 20 mEq/L

•• Citrate: 10 mmol/L (equivalent to 30 mEq/L base)

•• Glucose: 75 mmol/L

•Total Osmolarity = 245 mOsm/L (Reduced osmolarity reduces stool output and vomiting).

📋Key Takeaways & Exam Highlights

Normal Saline (0.9% w/v NaCl): Isotonic with human plasma (Osmolarity ~308 mOsm/L; 154 mEq/L $Na^+$ + 154 mEq/L $Cl^-$).
Ringer's Injection: Contains $NaCl + KCl + CaCl_2$ matching plasma electrolyte profile.
Dextrose Normal Saline (DNS): 5% Dextrose + 0.9% NaCl (provides 170 kcal/L plus hydration).
Trisodium Citrate Advantage over Sodium Bicarbonate: Citrate is far more chemically stable in tropical packaging, preventing discoloration and caramelization of dextrose in humid storage.

🇮🇳 हिन्दी व्याख्या (2. Electrolyte Replacement Therapy: ORS (WHO/IP Standard) & IV Fluids)

ORS (ओआरएस) में सोडियम क्लोराइड (2.6g), पोटैशियम क्लोराइड (1.5g), सोडियम सिट्रेट (2.9g) और ग्लूकोज (13.5g) को 1 लीटर पानी में घोला जाता है। ग्लूकोज आंतों में सोडियम और पानी को तेजी से सोखने में मदद करता है।