Bacitracin, neomycin, polymyxin Ophthalmic

Most polymyxin B sold for human use in the United States is in dermatological, otic, and ophthalmic preparations that usually contain one or more other spectmm extending antibacterials such as bacitracin, neomycin sulfate [1404-04-2], C23H4gNg023, linear gramicidin, oxytetracycline [79-57-2],... 

Rx with chloramphenicol (Chloromycetin/HC suspension—ophthalmic) with neomycin and polymyxin B (Cortisporin Otic, Drotic, Otocort—otic) with neomycin, polymyxin B, and bacitracin (Cortisporin Ointment, Neotricin HC—ophthalmic) with oxytetracycline (Terra-Cortril—ophthalmic) with urea (Carmol HC)... 

Neomycin is not usually administered parenter-ally to animals because of nephrotoxicity and ototoxicity. Only 3% of a dose of neomycin is absorbed following p.o. administration it is, therefore, used in the therapy of coliform enteritis in small and large animals. It is available as tablets, boluses and water additives, in many different combinations with antibiotics, corticosteroids and anticholinergic agents. It can also be used to decrease nitrogenous waste production by the normal gastrointestinal flora in animals with hepatic encephalopathy. Neomycin is not absorbed through the skin, so it is frequently utilized as the antibacterial constituent in ophthalmic formulations (especially in combination with bacitracin and polymyxin B) and in preparations for the treatment of otitis externa in small animals. 

Although tyrothricia is too toxic for parenteral therapy, it was formerly sold in the United States as oral lo2enges. Modem tyrothricin formulations are composed of 70—80% tyrocidines and 30—20% linear gramicidins. Tyrocidines are not as active as linear gramicidins and are too toxic for any therapeutic use by themselves. The bactericidal linear gramicidins are used in the United States solely as an ophthalmic solution in combination with polymyxin B sulfate and neomycin sulfate. The linear gramicidin is used in this aqueous product as a substitute for bacitracin, which lacks stabiUty under such conditions. 

Neosporin Ophthalmic Ointment—polymyxin B sulfate, neomycin, bacitracin zinc... 

Note Bacitracin is supplied in many forms and vehicles Intramuscular topical, ophthalmic, otic, aerosols, for irrigations. Many Bacitracin ointments are combinations with Neomycin and Polymyxin B. 

The neomycin and polymyxin B sulfates and bacitracin zinc ophthalmic ointment is a sterile antimicrobial ointment for ophthalmic use. Each gram contains neomycin sulfate... 

Bacitracin is available in ophthalmic and dermatologic ointments the antibiotic also is available as a powder for the preparation of topical solutions. The ointments are applied directly to the involved surface one or more times daily. A number of topical preparations of bacitracin, to which neomycin or polymyxin or both have been added, are available, and some contain the three antibiotics plus hydrocortisone. For open infections such as infected eczema and infected dermal ulcers, the local application of the antibiotic may be of some help in eradicating sensitive bacteria. Bacitracin rarely produces hypersensitivity. Suppurative conjunctivitis and infected comeal ulcer respond well to the topical use of bacitracin when caused by susceptible bacteria. Bacitracin has been used with limited success for eradication of nasal carriage of staphylococci. Oral bacitracin has been used with some success for the treatment of antibiotic-associated diarrhea caused by C. difficile. Serious nephrotoxicity results from the parenteral use of bacitracin. Hypersensitivity reactions rarely result from topical application. 

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