General Toxicity

• Systemic absorption of neomycin occurs following oral administration and toxic reactions may occur. Patients treated with neomycin should be under close observations because of the potential toxicity associated with their use.

Neurotoxicity, Nephrotoxicity, Ototoxicity

• Neurotoxicity (including ototoxicity) and nephrotoxicity following the oral use of neomycin sulfate have been reported, even when used in recommended doses.
• The potential for nephrotoxicity, permanent bilateral auditory ototoxicity and sometimes vestibular toxicity is present in patients with normal renal function when treated with higher doses of neomycin and/or for longer periods than recommended.
• Serial, vestibular, and audiometric tests as well as tests of renal function, should be performed(especially in high risk patients).
• The risk of nephrotoxicity and ototoxicity is greater in patients with impaired renal function.
• Ototoxicity is often delayed in onset and patients developing cochlear damage will not have symptoms during therapy to warn of them of developing eighth nerve destruction and total or partial deafness may occur long after neomycin has been discontinued.
• Neuromuscular blockage and respiratory paralysis have been reported following the oral use of neomycin. THe possibility of the occurrence of neuro-muscular blockage and respiratory paralysis should be considered if neomycin is administered, especially to patients receiving anesthetics, neuromuscular blocking agents such as tubocurarine, succinylcholine, decamethonium, or in patients receiving massive transfusions of citrate anticoagulated blood. If blockage occurs, calcium salts may reverse these phenomena but mechanical respiratory assistance may be necessary.
• Concurrent and/or sequential systemic, oral, or topical use of other aminoglycosides including paromomycin and other potentially nephrotoxic and/or neurotoxic drugs such as bacitracin, cisplatin, vancomycin, amphotericin B, polymixin B, colistin, and viomycin should be avoided because the toxicity may be additive.
• Other factors which increase the risk of toxicity are advanced age and dehydration.
• The concurrent use of neomycin with potent diuretics such as ethacrynic acid or furosemide should be avoided since certain diuretics by themselves may cause ototoxicity. In addition, when administered intravenously, diuretics may enhance neomycin toxicity by altering the antibiotic concentration in serum and tissue.