Which medication is described as an antibiotic ointment?

• A. Erythromycin
• B. Vigamox
• C. Ofloxacin
• D. Acetazolamide

Answer: (A)

Erythromycin is described as an antibiotic ointment because it is traditionally formulated as an ophthalmic ointment for topical use on the eye. The ointment form stays on the surface longer, providing sustained exposure to bacteria that cause conjunctivitis or blepharitis, which is a key reason this preparation is described as an antibiotic ointment. Erythromycin belongs to the macrolide class and works by inhibiting bacterial protein synthesis, helping to curb infection on the ocular surface. The other options are antibiotics used as eye drops (solutions) rather than ointments, or in a non-antibiotic role altogether, with acetazolamide being a carbonic anhydrase inhibitor used to lower intraocular pressure rather than treating infections. Therefore, the ointment formulation of erythromycin makes it the match for an antibiotic ointment.