**Question:** Antidote for oxalic acid poisoning is

A. Calcium gluconate
B. Vitamin C
C. Glucose and insulin
D. Insulin

**Correct Answer:** A. Calcium gluconate

**Core Concept:**
The antidote for oxalic acid poisoning primarily targets the inhibition of oxalate absorption and neutralization of oxalate ions. Oxalic acid is a carboxylic acid that can cause severe systemic toxicity when ingested, leading to hyperoxaluria, hypercalciuria, and ultimately, oxalate nephropathy. Calcium salts, like calcium gluconate, are effective in neutralizing oxalate ions and reducing its systemic absorption.

**Why the Correct Answer is Right:**
Calcium gluconate is the appropriate antidote for oxalic acid poisoning because it neutralizes the oxalate ions produced by the breakdown of oxalic acid. Calcium ions form insoluble calcium oxalate crystals, which precipitate out of the blood, preventing further absorption and reducing the severity of systemic toxicity.

**Why Each Wrong Option is Incorrect:**

A. Vitamin C (B) is not an effective antidote for oxalic acid poisoning because it does not neutralize oxalate ions or inhibit oxalate absorption.

B. Glucose and insulin (C) are used in the management of diabetic ketoacidosis, not oxalic acid poisoning. They do not neutralize oxalate ions or prevent oxalate absorption.

D. Insulin (D) is used in the management of hyperglycemic emergencies like diabetic ketoacidosis, not oxalic acid poisoning. Insulin does not neutralize oxalate ions or inhibit oxalate absorption.

**Clinical Pearl:**
Oxalic acid poisoning is a rare but severe condition that can result in life-threatening complications like oxalate nephropathy. Early recognition and administration of calcium salts like calcium gluconate can significantly reduce the severity of the poisoning and its systemic effects. Always consult a medical expert for proper management of such cases, as the treatment may vary depending on the severity and duration of oxalate poisoning. In severe cases, dialysis may also be required.