Step 1: What is Ketoconazole?
Ketoconazole is a broad-spectrum antifungal drug used for systemic and superficial fungal infections. It works by inhibiting the enzyme lanosterol 14-alpha-demethylase (a CYP450 enzyme), which is needed to make ergosterol, the main sterol in fungal cell membranes.
Step 2: Chemical classification of antifungals.
Azole antifungals are classified by the number of nitrogen atoms in their azole ring: imidazoles have 2 nitrogens (e.g., ketoconazole, miconazole, clotrimazole) and triazoles have 3 nitrogens (e.g., fluconazole, itraconazole, voriconazole).
Step 3: Identify Ketoconazole's class.
Ketoconazole has an imidazole ring in its structure. It was one of the first oral azole antifungals. Its chemical name includes the imidazole moiety. It is correctly classified as an imidazole antifungal.
Step 4: Eliminate wrong options.
Triazole: applies to fluconazole, itraconazole, not ketoconazole. Polyene: applies to amphotericin B and nystatin (completely different structure, binds ergosterol directly). Tetrazole: a 4-nitrogen ring, not used in antifungals like ketoconazole.
Step 5: Confirm.
Ketoconazole is chemically an imidazole derivative.
Answer: Option (2) — Imidazole