**Question:** Activated charcoal is used in -

A. Gastric lavage
B. Oral rehydration therapy
C. Hemodialysis
D. Injection therapy

**Core Concept:**
Activated charcoal is a form of carbon that has been processed to increase its surface area, making it highly effective in absorbing toxic substances and reducing their absorption in the gastrointestinal tract. It is commonly used in the treatment of poisoning cases where an antidote is not available or sufficient.

**Why the Correct Answer is Right:**
Activated charcoal is mainly used in the treatment of poisoning cases. It works by adsorption, a process where charcoal binds to toxic substances on its surface, preventing them from being absorbed into the bloodstream and distributed to vital organs.

**Why Each Wrong Option is Incorrect:**
A. Gastric lavage: This is a procedure where the stomach is emptied using a tube. Activated charcoal is not used in gastric lavage as it would be wasted during the lavage process.
B. Oral rehydration therapy: This is a method used to treat dehydration due to diarrhea. Activated charcoal is not required in oral rehydration therapy, as the primary focus is on restoring fluid and electrolyte balance.
C. Hemodialysis: Hemodialysis is a renal replacement therapy used to remove excess waste products and electrolytes from the blood. Activated charcoal is not used in hemodialysis as it is a gastrointestinal procedure and not renal.
D. Injection therapy: Activated charcoal is usually administered orally or via nasogastric tube, not intravenously. Injection therapy involves administering medications or substances directly into the bloodstream, which is not the case with activated charcoal.

**Clinical Pearl:**
In cases of poisoning, activated charcoal can be administered orally or via nasogastric tube to neutralize the absorbed toxins in the gastrointestinal tract. Its effectiveness depends on the timing of administration relative to the ingestion of the toxic substance. If given within 1 hour of toxin ingestion, it can reduce the absorption of a wide range of toxic substances, thereby improving patient outcomes.