Polymyxin steroids with

Polymyxin B is not used systemically because of its neurotoxicity and nephrotoxicity. Topically, it is used in combination with other antibacterial drugs or steroids to prevent and treat skin infections and external otitis. 

Ocular polymyxin B is commercially available in combination with other antibiotics (see Table 11-6) or with steroids (seeTable 11-7) to treat infections of the lids and conjunctiva. It is also used to prevent infection when the conjunctiva or cornea is compromised or when a steroid is used. 

If a significant inflammatory component or a response to bacterial exotoxin hypersensitivity in the fiarm of marginal corneal infiltrates or phlyctenules is present, treatment may require concurrent topical steroid therapy. When chronic dacryocystitis is involved, treatment should include irrigation of the lacrimal system with trimethoprim-polymyxin B or gentamicin. Adjunctive systemic antibiotic therapy may also be required (see Chapter 24). 

Although topical antibiotics are used frequently in the management of ocular rosacea, no firm evidence demonstrates their efficacy as a sole therapeutic agent. Topical steroids, however, are effective for treating the inflammatory aspects and frequently are used four times daily in conjimction with antibiotics in combination products such asTobraDex (tobramycin-dexamethasone), Pred-G (gentamicin-prednisone), or Maxitrol (neomycin-polymyxin B-dexamethasone). Because of potential steroid-induced side effects, chronic use of these agents should be avoided. 

Neomycin currently is available in many brands of creams, ointments, and other products alone and in combination with polymyxin, bacitracin, other antibiotics and a variety of corticosteroids. There is no evidence that these topical preparations shorten the time required for healing of wounds or that those containing a steroid are more effective. 

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