Polymyxin B

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],... 

Some polymyxins are sold for second-line systemic therapy. Polymyxin B sulfate and colistimethate sodium can be used for intravenous, intramuscular, or intrathecal administration, especially for Pseudomonas aerupinosa mP QXiosis, but also for most other gram-negative organisms, such as those resistant to first-line antibiotics. Nephrotoxicity and various neurotoxicities are common in parenteral, but not in topical, use. Resistance to polymyxins develops slowly, involves mutation and, at least in some bacteria, adaptation, a poorly understood type of resistance that is rapidly lost on transfer to a medium free of polymyxin. Resistance can involve changes in the proteins, the lipopolysaccharides, and lipids of the outer membrane of the cell (52). Polymyxin and colistin show complete cross-resistance. 

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. 

Nystatin (100,000 lU) is also available in combination with neomycin sulfate [1405-10-3] (35,000 lU), polymyxin B sulfate [1405-20-5] (35,000 lU), acetarsol [97-44-9] (150 mg), and dimethicone [8050-81-5] (2,500 mg). One or two ovules per day are inserted vaginaHy for at least 6—12 days. This combination has an antibacterial, antimycotic, and antitrichomonas action (see also Antibiotics, oligosaccharides Antiparasitic agents, antiprotozoals). 

Polymyxin B Bacillus polymyxa Gram-negative bacteria Cell membrane... 

AK-Fbly-Bac Ophthalmic Ointment—polymyxin B sulfate, bacitracin zinc... 

Fblytrim Ophthalmic Solution—polymyxin B sulfate, trimethoprim sulfate... 

Otosporia (Warner-Lambert)-comb. Polymyxin B sulfate (Pfizer)... 

Polytrim (Dominion)-comb. with polymyxin B Septrin (Glaxo Wellcome)-comb. 

The antibacterial activity of five members (A to E) of the polymyxin group is of a similar nature. However, they are all nephrotoxic although this effect is much reduced with polymyxins B and E (colistin). Colistin sulphomethate sodium is the form of colistin used for parenteral administration. Sulphomyxin sodium, a mixture of sulphomethylated polymyxin B and sodium bisulphite, has the action and uses of polymyxin B sulphate, but is less toxic. 

FIG. 9 A scheme representing lateral phase separation for anionic lipids from zwitterionic lipids in a mixed lipid bilayer induced by the peptide antibiotic, polymyxin-B. (Reprinted by permission from Ref. 41, copyright 1998, Elsevier Science.)... 

Poliovirus, inactivated IPV 0.5 mL Intramuscular, subcutaneous Allergic reaction to neomycin, streptomycin, polymyxin B... 

Polypeptides Bacitracin, colistin, and polymyxin B Eye, ear, or bladder infections... 

United States Pharmacopoeia 28 [1] describes a microbiological method under antibiotics-microbial assays for the analysis of OTC and nystatin capsules, OTC and nystatin for oral suspension, OTC HC1 and hydrocortisone ointment, and OTC HC1 and polymyxin B sulfate ointment. The methods are relative rather than absolute, which are based on the determination of the level of oxytetracycline by a microbiological response to a series of standard oxytetracycline concentrations by a... 

Systemic therapy with a variety of (3-lactams, macro-lides and lincosamides (clindamycin) has been the cornerstone of skin infection therapy for many years [17]. However, topical antibiotics can play an important role in both treatment and prevention of many primary cutaneous bacterial infections commonly seen in the dermatological practice [18], Indeed, while systemic antimicrobials are needed in the complicated infections of skin and skin structure, the milder forms can be successfully treated with topical therapy alone [18], The topical agents used most often in the treatment of superficial cutaneous bacterial infections are tetracyclines, mupirocin, bacitracin, polymyxin B, and neomycin. 

The answer is a. (Hardman, pp 1143-1144.) Polymyxin B is poorly absorbed by the oral route. It is primarily administered by the topical route for the treatment of infections of the skin, mucous membranes, eye, and ear. Penicillin G can be administered both orally and parenterally. Did oxacillin is only given by the oral route. Carbenicillin and streptomycin are administered only by the parenteral route. 

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