Neomycin and polymyxin B sulfates and bacitracin zinc ophthalmic ointment, USP is a sterile antimicrobial ointment for topical ophthalmic use.

Each gram contains

Actives:neomycin sulfate equivalent to 3.5 mg neomycin base, polymyxin B sulfate equivalent to 10,000 polymyxin B units, and bacitracin zinc equivalent to 400 bacitracin units; Inactives:white petrolatum and mineral oil.

Neomycin sulfate is the sulfate salt of neomycin B and C, which are produced by the growth of Streptomyces fradiaeWaksman (Fam. Streptomycetaceae). It has a potency equivalent of not less than 600 micrograms of neomycin standard per mg, calculated on an anhydrous basis. The structural formulae are:

Polymyxin B sulfate is the sulfate salt of polymyxin B 1and B 2which are produced by the growth of Bacillus polymyxa(Prazmowski) Migula (Fam. Bacillaceae). It has a potency of not less than 6,000 polymyxin B units per mg, calculated on an anhydrous basis.

The structural formulae are:

Bacitracin zinc is the zinc salt of bacitracin, a mixture of related cyclic polypeptides (mainly bacitracin A) produced by the growth of an organism of the licheniformisgroup of Bacillus subtilisvar Tracy. It has a potency of not less than 40 bacitracin units per mg.