## Core Concept
Drug-induced pemphigus is a rare autoimmune disorder caused by certain medications that trigger the production of autoantibodies against desmoglein proteins, leading to blistering of the skin and mucous membranes. Pemphigus is characterized by the formation of intraepithelial blisters due to the loss of cell-cell adhesion between keratinocytes. The condition can be induced by various drugs.

## Why the Correct Answer is Right
The correct answer, **Penicillamine**, is a well-known cause of drug-induced pemphigus. Penicillamine is a chelating agent used in the treatment of Wilson's disease, cystinuria, and rheumatoid arthritis. It can induce pemphigus by triggering the production of autoantibodies against desmoglein 3 proteins, which are crucial for maintaining adhesion between epidermal cells. This leads to the characteristic blistering seen in pemphigus.

## Why Each Wrong Option is Incorrect
* **Option A:** While certain antibiotics can cause a variety of skin reactions, they are not the most commonly associated with drug-induced pemphigus.
* **Option B:** Similarly, antihistamines can cause skin reactions but are not commonly linked to pemphigus.
* **Option D:** Though various drugs can induce pemphigus, **Penicillamine** is specifically noted for its association with this condition.

## Clinical Pearl / High-Yield Fact
A key point to remember is that drug-induced pemphigus can often be reversed by discontinuing the offending medication. However, in some cases, the condition may persist even after the drug is stopped, requiring immunosuppressive therapy. A classic association to recall is that **Penicillamine** and **Captopril** are drugs that have been commonly implicated in drug-induced pemphigus.

**Correct Answer: C. Penicillamine**