Pharmacia & Upjohn
Action And Clinical Pharmacology: Neomycin is an aminoglycoside antibiotic, active against many strains of Gram-negative bacteria. Neomycin is poorly absorbed from the normal gastrointestinal tract. The small absorbed fraction is rapidly distributed in the tissues and is excreted by the kidney in keeping with the degree of kidney function. The unabsorbed portion of the drug (approximately 97%) is eliminated unchanged in the feces.
Growth of most intestinal bacteria is rapidly suppressed following oral administration of neomycin, with the suppression persisting for 48 to 72 hours. Nonpathogenic yeasts and occasionally resistant strains of E. aerogenes (formerly A. aerogenes) replace the intestinal bacteria.
As with other aminoglycosides, the amount of systemically absorbed neomycin transferred to the tissues increases cumulatively with each repeated dose administered until a steady state is achieved. The kidney functions as the primary excretory path as well as the tissue binding site with the highest concentration found in the renal cortex. With repeated dosings, progressive accumulation also occurs in the inner ear. Release of tissue bound neomycin occurs slowly over a period of several weeks after dosing has been discontinued.
Protein binding studies have shown that the degree of aminoglycoside protein binding is low and depending upon the methods used for testing, this may be between 1 and 30%.
Indications And Clinical Uses: For adjunctive therapy in the preoperative preparation of the bowel prior to abdominal or perineal surgery involving the lower intestinal tract. Neomycin has also proved a valuable adjunct in the management of hepatic coma by reducing the ammonia-forming bacteria in the intestinal tract.
Contra-Indications: In the presence of intestinal obstruction and in individuals with a history of hypersensitivity to the drug.
Patients with a history of hypersensitivity or serious toxic reaction to other aminoglycosides may have a cross-sensitivity to neomycin.
Also contraindicated in patients with inflammatory or ulcerative gastrointestinal disease because of the potential for enhanced gastrointestinal absorption of neomycin.
Manufacturers’ Warnings In Clinical States: Systemic absorption of neomycin occurs following oral administration, and toxic reactions may occur. Patients treated with neomycin should be under close clinical observation because of the potential toxicity associated with their use.
Neurotoxicity (including ototoxicity) and nephrotoxicity following the oral use of neomycin 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 them of developing eighth nerve destruction and total or partial deafness may occur long after neomycin has been discontinued.
Neuromuscular blockade and respiratory paralysis have been reported following the oral use of neomycin. The possibility of the occurrence of neuromuscular 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, polymyxin 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 i.v., diuretics may enhance neomycin toxicity by altering the antibiotic concentration in serum and tissue.
Additional manifestations of neurotoxicity may include numbness, skin tingling, muscle twitching, and convulsions.
The risk of hearing loss continues after drug withdrawal.
Pregnancy: Aminoglycosides can cause fetal harm when administered to a pregnant woman. Aminoglycoside antibiotics cross the placenta and there have been several reports of total irreversible bilateral congenital deafness in children whose mothers received streptomycin during pregnancy. Although serious side effects to fetus or newborn have not been reported in the treatment of pregnant women with other aminoglycosides, the potential for harm exists. Animal reproduction studies of neomycin have not been conducted. If neomycin is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.
Precautions: General: As with other antibiotics, use of oral neomycin may result in overgrowth of nonsusceptible organisms, particularly fungi. If this occurs, appropriate therapy should be instituted.
Neomycin is quickly and almost totally absorbed from body surfaces (except the urinary bladder) after local irrigation and when applied topically in association with surgical procedures. Delayed-onset, irreversible deafness, renal failure, and death due to neuromuscular blockade (regardless of the status of renal function) have been reported following irrigation of both small and large surgical fields with minute quantities of neomycin.
Aminoglycosides should be used with caution in patients with muscular disorders such as myasthenia gravis or parkinsonism since these drugs may aggravate muscle weakness because of their potential curare-like effect on the neuromuscular junction.
Small amounts of orally administered neomycin are absorbed through intact intestinal mucosa. The drug may be absorbed from ulcerated or denuded areas.
There have been many reports in the literature of nephrotoxicity and/or ototoxicity with the oral use of neomycin. If renal insufficiency develops during oral therapy, consideration should be given to reducing the drug dosage or discontinuing therapy.
An oral neomycin dose of 12 g/day produces a malabsorption syndrome for a variety of substances including fat, nitrogen, cholesterol, carotene, glucose, xylose, lactose, sodium, calcium, cyanocobalamin and iron.
Orally administered neomycin increases fecal bile acid excretion and reduces intestinal lactase activity.
Laboratory Tests: Patients with renal insufficiency may develop toxic neomycin blood levels unless doses are properly regulated. If renal insufficiency develops during treatment, the dosage should be reduced or the antibiotic discontinued. To avoid nephrotoxicity and eighth nerve damage associated with high doses and prolonged treatment, the following should be performed prior to and periodically during therapy: urinalysis for increased excretion of protein, decreased specific gravity, casts and cells; renal function tests such as serum creatinine, BUN or creatinine clearance; tests of the vestibulocochlearis nerve (eighth cranial nerve) function.
Serial, vestibular and audiometric tests should be performed (especially in high risk patients). Since elderly patients may have reduced renal function which may not be evident in the results of routine screening tests such as BUN or serum creatinine, a creatinine clearance determination may be more useful.
Drug Interactions: Caution should be taken in concurrent or serial use of other neurotoxic and/or nephrotoxic drugs because of possible enhancement of the nephrotoxicity and/or ototoxicity of neomycin (see Warnings).
Caution should also be taken in concurrent or serial use of other aminoglycosides and polymyxins because they may enhance neomycin’s nephrotoxicity and/or ototoxicity and potentiate neomycin’s neuromuscular blocking effects.
Oral neomycin inhibits the gastrointestinal absorption of penicillin V, oral vitamin B12, methotrexate and 5-fluorouracil. The gastrointestinal absorption of digoxin also appears to be inhibited. Therefore, digoxin serum levels should be monitored.
Oral neomycin may enhance the effect of coumarin anticoagulants by decreasing vitamin K availability.
Carcinogenesis, Mutagenesis, Impairment of Fertility: No long-term animal studies have been performed with neomycin to evaluate carcinogenic or mutagenic potential or impairment of fertility.
Lactation: It is not known whether neomycin is excreted in human milk but it has been shown to be excreted in cow milk following a single i.m. injection. Other aminoglycosides have been shown to be excreted in human milk. Because of the potential for serious adverse reactions from the aminoglycosides in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Children: The safety and efficacy of oral neomycin in patients less than 18 years of age have not been established. If treatment of a patient less than 18 years of age is necessary, neomycin should be used with caution and the period of treatment should not exceed 2 weeks because of absorption from the gastrointestinal tract.
Adverse Reactions: The most common adverse reactions to oral neomycin are nausea, vomiting and diarrhea. The “Malabsorption Syndrome” characterized by increased fecal fat, decreased serum carotene and fall in xylose absorption has been reported with prolonged therapy.
Nephrotoxicity, ototoxicity, and neuromuscular blockage have been reported (see Warnings and Precautions).
Symptoms And Treatment Of Overdose: Symptoms and Treatment: Because of low absorption, it is unlikely that acute overdosage would occur with oral neomycin. However, prolonged administration could result in sufficient systemic drug levels to produce neurotoxicity, ototoxicity, and/or nephrotoxicity.
Hemodialysis will remove neomycin from the blood.
Dosage And Administration: To minimize the risk of toxicity use the lowest possible dose and the shortest possible treatment period to control the condition. Treatment for periods longer than 2 weeks is not recommended.
Bowel Preparation Prior to Surgery: Where there is no contraindication to the use of neomycin, the following regimen is recommended. 1. Low-residue diet. 2. One gram of neomycin (2 tablets) immediately following a cathartic. Repeat dose every 4 hours to a total of 6 g. Preoperative treatment should ordinarily be carried out for 24 hours, and should not extend beyond 72 hours in any case.
Note: Neomycin is usually used in combination with erythromycin or metronidazole.
Hepatic Coma: For use as an adjunct in the management of hepatic coma, the recommended dose is 4 to 12 g/day given in the following regimen: 1. Withdraw protein from diet. Avoid use of diuretic agents. 2. Give supportive therapy including blood products, as indicated. 3. Give neomycin Oral Solution in doses of 4 to 12 g of neomycin/day in divided doses. Treatment should be continued over a period of 5 to 6 days during which time protein should be returned incrementally to the diet. 4. If less potentially toxic drugs cannot be used for chronic hepatic insufficiency, neomycin in doses of up to 4 g daily may be necessary. The risks for the development of neomycin induced toxicity progressively increase when treatment must be extended to preserve the life of a patient with hepatic encephalopathy who has failed to fully respond. Frequent periodic monitoring of these patients to ascertain the presence of drug toxicity is mandatory (see Precautions). Also, neomycin serum concentrations should be monitored to avoid potentially toxic levels. The benefits to the patient should be weighed against the risks of nephrotoxicity, permanent ototoxicity and neuromuscular blockade following the accumulation of neomycin in the tissues.
Availability And Storage: Oral Solution: Each 5 mL of clear red, cherry-flavored solution contains: neomycin sulfate 125 mg. Nonmedicinal ingredients: benzoic acid, cherry flavor, FD&C Red No. 4, glycerin, methylparaben, propylparaben, purified water, sodium cyclamate and sodium phosphate, standard supercel and sulfuric acid. Bottles of 100 mL.
Tablets: Each ivory, full oval, compressed tablet contains: neomycin sulfate 0.5 g. Nonmedicinal ingredients: alcohol, calcium stearate and povidone. Bottles of 100.
Store at controlled room temperature 15 to 30°C in tight, light-resistant containers. (Shown in Product Recognition Section)
MYCIFRADIN® Pharmacia & Upjohn Neomycin Sulfate Antibiotic
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