Which of the following Sulfonamides is used as eye drops?
**Core Concept**
Sulfonamides are a class of antimicrobials that inhibit folic acid synthesis in bacteria, leading to their bacteriostatic effect. Topical sulfonamides are used to treat ocular infections by reducing bacterial growth in the eye.
**Why the Correct Answer is Right**
The correct answer is Mafenide, which is a sulfonamide antibiotic used topically in the form of eye drops or creams to treat bacterial conjunctivitis and keratitis. Mafenide works by inhibiting dihydropteroate synthetase, an enzyme essential for the synthesis of folic acid in bacteria. This leads to the inhibition of bacterial growth and proliferation in the eye.
**Why Each Wrong Option is Incorrect**
**Option A:** Silver Sulfadiazine is a sulfonamide antibiotic used topically to treat burns, but it is not used as eye drops.
**Option B:** Sulfacetamide is a sulfonamide antibiotic used topically to treat bacterial conjunctivitis, but it is not the correct answer as it is not used as eye drops.
**Option C:** Sulfadiazine is a sulfonamide antibiotic used systemically to treat bacterial infections, but it is not used as eye drops.
**Clinical Pearl / High-Yield Fact**
Topical sulfonamides, such as Mafenide and Sulfacetamide, are commonly used to treat ocular infections due to their ability to reduce bacterial growth and proliferation in the eye without causing significant systemic side effects.
**Correct Answer: C. Mafenide.**