Aminoglycosides topical

Patomomycin This oral aminoglycoside was first shown to be effective as a topical treatment for cutaneous leishmaniasis, and later as a parenteral drug against visceral leishmaniasis. Phase III clinical trials were completed in 2005 in India, 15 years after the potential of this component for treating viscer al leishmaniasis was discovered. It is currently not registered for this use. 

Gentamicin is an aminoglycoside. As aminoglycosides are not absorbed from the gastrointestinal tract, gentamicin is only presented for parenteral or topical use (as eye/ear drops). 

The biochemical mode of action of the aminoglycosides as antibacterials has long been a topic of great interest. Early experiments carried out soon after the introduction of streptomycin suggested a variety of modes of action, but these conclusions were based largely on symptomatic analyses of antibiotic-treated bacterial cultures. One important experiment done in 1948 showed that streptomycin blocks enzyme indnction in susceptible bacteria this was the closest that anyone came to identifying the mechanism of action at the time. 

Topical use Aminoglycosides are quickly and almost totally absorbed when applied topically in association with surgical procedures, except to the urinary bladder. 

Uses Prevent skin Infxn Action Topical aminoglycoside Dose Apply to skin and rub in Caution [C, /-] Contra Component aU gy Disp Cream SE Itching, rash, redness EMS See Neomycin Sulfate OD Unlikely... 

Generally replaced by the aminoglycosides or extended-spectrum penicillins for serious infections still used for bladder irrigation and gut decontamination used in combination wit hot her antibiotics and/or corticosteroids topically to treat infections of the eye and skin... 

Neomycin and kanamycin are now limited to topical and oral use. Neomycin is too toxic for parenteral use. With the advent of more potent and less toxic aminoglycosides, parenteral administration of kanamycin has also been largely abandoned. Paromomycin has recently been shown to be effective against visceral leishmaniasis when given parenterally (see Chapter 52), and this serious infection may represent an important new use for this drug. 

Topical Antibiotic Monotherapy Localized impetiginized eczema lesions can be treated successfully with topical fusidic acid or mupirocin, whereas topical application of other antibiotics (neomycin as obsolete aminoglycosid, tetracyclines, or polymyxines) should be avoided.84 Especially in children with AD, fusidic acid resistance seems to be a particular problem reflecting the chronicity and the extent of the disease (see Section 30.2.2). 

Administration The highly polar, polycationic structure of the aminoglycosides prevents adequate absorption after oral administration. Therefore, all aminoglycosides (except neomycin [nee oh MYE sin]) must be given parenterally to achieve adequate serum levels. [Note The severe nephrotoxicity associated with neomycin precludes parenteral administration, and its current use is limited to topical application or oral treatment in hepatic coma to reduce the intestinal bacterial population.]... 

Additive renal toxic effects may occur with immunosuppressants (e.g. azathioprine, ciclosporin, tacrolimus), ACE inhibitors, penicillamine, irinotecan and aminoglycoside antibiotics. A deterioration of renal function may even occur after the topical use of NSAIDs. Guidelines are variable for the use of NSAIDs with differing degrees of renal function, as assessed by creatinine clearance measurements. 

Aminoglycosides are poorly absorbed from the gastrointestinal tract, so when used systemically they must be given parenterally. Note that penicillins or cephalosporins can inactivate aminoglycosides if mixed together in the same solution fiar injection or fiar topical application each drug must be administered separately. If topical fortified cefazolin and fortified tobramycin are used to treat a corneal ulcer, each should be prepared and administered in a separate bottle. 

Neomydn. Neomycin is the oldest aminoglycoside. It is available for oral, topical, and parenteral administration, but there are almost no indications for oral and parenteral use. 

Neomycin is a topical aminoglycoside widely nsed for skin wounds and in otolaryngology. Its antibacterial activity resembles that of gentamicin and tobramycin, except that P aeruginosa, S. pneumoniae, and the a-hemolytic streptococci are generally resistant. Neomycin s usefnl-ness for treating acnte bacterial conjunctivitis is limited... 

The conjvinctivitis associated with Reiter s syndrome is usually mild and transient.A topical aminoglycoside, erythromycin, or a combination agent such as trimethoprim-polymyxin B (Polytrim) may be used to treat more severe conjimctivitis. 

More severe forms of toxic keratitis may require prophylactic antibiotic therapy to protect the inflamed cornea. The use of topical aminoglycosides should be avoided, however, as they tend to exacerbate the condi-tion.The use of a mild steroid, such as 0.12% prednisolone drops four times a day, aids the resolution of more advanced cases. Any allergic component involving the eyelids or conjunctiva should be treated appropriately. 

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