Neosporin Ophthalmic Solution (neomycin and polymyxin B sulfates and gramicidin ophthalmic solution) is a sterile antimicrobial solution for ophthalmic use. Each mL contains: neomycin sulfate equivalent to 1.75 mg neomycin base, polymyxin B sulfate equivalent to 10,000 polymyxin B units, and gramicidin 0.025 mg. The vehicle contains alcohol 0.5%, thimerosal 0.001% (added as a preservative), and the inactive ingredients propylene glycol, polyoxyethylene polyoxypropylene compound, sodium chloride, and Water for Injection.

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

Polymyxin B sulfate is the sulfate salt of polymyxin B1 and B2 which 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:

Gramicidin (also called Gramicidin D) is a mixture of three pairs of antibacterial substances (Gramicidin A, B, and C) produced by the growth of Bacillus brevis Dubos (Fam. Bacillaceae). It has a potency of not less than 900 µg of standard gramicidin per mg. The structural formulae are:^[1]

Adapted from the FDA Package Insert.