## **Core Concept**
Isoniazid is a first-line antitubercular medication known to cause peripheral neuropathy as a side effect. This condition arises due to the interference with the metabolism of a specific vitamin. The prevention of this side effect involves supplementation with a particular vitamin.

## **Why the Correct Answer is Right**
Isoniazid-induced peripheral neuropathy is primarily caused by its interference with the metabolism of **pyridoxine (Vitamin B6)**. Isoniazid forms a hydrazone with pyridoxal phosphate, which is then excreted, leading to a deficiency of vitamin B6. Vitamin B6 plays a crucial role in the synthesis of neurotransmitters and myelin, and its deficiency can lead to neuropathy. Supplementing with **pyridoxine (Vitamin B6)** helps prevent this neuropathy without significantly affecting the antitubercular efficacy of isoniazid.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Vitamin B12 is crucial for the synthesis of myelin and the maintenance of the nervous system, but its deficiency leads to a different type of neuropathy, and it is not directly related to isoniazid-induced neuropathy.
- **Option B:** Vitamin B2 (Riboflavin) is important for energy production and can help with migraines but is not directly involved in preventing isoniazid-induced neuropathy.
- **Option D:** Vitamin B3 (Niacin) is essential for skin, hair, and brain function but is not specifically used to prevent peripheral neuropathy caused by isoniazid.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that isoniazid-induced peripheral neuropathy can be effectively prevented by administering **pyridoxine (Vitamin B6)**, 10-25 mg/day, alongside isoniazid. This is a critical preventive measure, especially in high-risk patients, such as those with a history of neuropathy or poor nutritional status.

## **Correct Answer:** . Pyridoxine (Vitamin B6)