Brand names: Neo-Fradin, Neo-Rx
Drug class: Aminoglycosides
CAS number: 1405-10-3

Introduction

Antibacterial; aminoglycoside antibiotic obtained from cultures of Streptomyces fradiae.^{1 2 14 23}

Uses for Neomycin

Hepatic Encephalopathy

Management of hepatic encephalopathy.^{1 2 11 13 26 27 28} Used to inhibit ammonia-forming bacteria in the GI tract in patients with hepatic (portal-systemic) encephalopathy as an adjunct to protein restriction and supportive therapy.^{1 2 11 13 26 27 28} Subsequent reduction in blood ammonia may result in neurologic improvement.^{1 2 11 27}

Although efficacy of such adjunctive treatment is not clearly established,¹² it has been suggested that nonabsorbable disaccharides (lactulose) are first-line treatment to reduce blood ammonia in adults with acute hepatic encephalopathy and anti-infectives (e.g., oral neomycin or metronidazole) are alternatives.^{11 28}

Perioperative Prophylaxis

Adjunct to mechanical cleansing of the large intestines for preoperative prophylaxis in patients undergoing colorectal surgery.^{2 3 6 13} Used in conjunction with oral erythromycin or oral metronidazole and with an appropriate diet and catharsis.^{2 3 6}

Preferred regimens for patients undergoing colorectal surgery are IV cefoxitin or IV cefotetan alone; IV cefazolin and IV metronidazole; oral erythromycin and oral neomycin; or oral metronidazole and oral neomycin.^{3 6}

Hypercholesterolemia

Treatment of hypercholesterolemia^{† [off-label]}.^{13 16 17 20 25} Therapeutic value may be due in part to reduction in GI absorption of cholesterol, resulting in enhanced elimination of cholesterol as neutral sterols in the feces.^{13 16 20}

Not a first- or second-line agent; use only after all conventional treatments have been tried.^{18 25}

GI Infections

Not recommended for treatment of any GI infections^{† [off-label]}.¹³

Neomycin Dosage and Administration

Administration

Oral Administration

Administer orally.^{1 2}

Dosage

Available as neomycin sulfate; dosage expressed in terms of the sulfate.^a

To minimize risk of toxicity, use lowest possible dosage and shortest duration of therapy.^{1 2} Closely monitor patients for aminoglycoside toxicity, especially when used for adjunctive treatment of chronic hepatic insufficiency.^{1 2 11}

Treatment duration >2 weeks is not recommended.^{1 2} Weigh risks of nephrotoxicity, permanent ototoxicity, and neuromuscular blockade against benefits of prolonged treatment.¹ If treatment is prolonged, closely monitor serum neomycin concentrations and renal, auditory, and vestibular functions.¹

Individualize dosage taking into consideration the patient’s pretreatment body weight, renal status, and serum concentrations of the drug.^b Because of potential toxicity, fixed-dosage recommendations that are not based on patient weight or serum drug concentrations are not advised.^b

Pediatric Patients

General Pediatric Dosage

Oral

Neonates ≤1 month of age^{† [off-label]}: AAP recommends 25 mg/kg every 6 hours.⁵

Infants and children >1 month of age^{† [off-label]}: AAP recommends 100 mg/kg daily given in 4 equally divided doses.⁵

Manufacturers state that if neomycin is considered necessary in children <18 years of age^{† [off-label]}, duration of therapy should not exceed 2 weeks^{1 2} . (See Pediatric Use under Cautions.)

Hepatic Encephalopathy

Oral

Children^†: 100 mg/kg daily given in 4 divided doses for ≤7 days.²⁷

Prior to initiation of neomycin, withdraw protein from the diet and avoid diuretics; incrementally return protein back to the diet during treatment.^{1 2} Monitor closely;^{1 2 11} give supportive therapy (including blood products) as indicated.^{1 2}

Adults

Hepatic Encephalopathy

Oral

Hepatic coma: 4–12 g daily given in divided doses (e.g., 4 doses daily) for 5–6 days recommended by the manufacturers and others.^{1 2 26 28}

Chronic hepatic insufficiency when less toxic drugs cannot be used: Up to 4 g daily recommended by the manufacturers.^{1 2}

Some clinicians recommend 3–6 g daily for 1–2 weeks for acute encephalopathy¹¹ and 1–2 g daily for chronic encephalopathy.¹¹

Prior to initiation of neomycin, withdraw protein from the diet and avoid diuretics; incrementally return protein back to the diet during treatment.^{1 2} Monitor closely;^{1 2 11} give supportive therapy (including blood products) as indicated.^{1 2}

Perioperative Prophylaxis

Adjunct to Mechanical Cleansing in Patients Undergoing Colorectal Surgery

Oral

For 8 a.m. surgery: Give 1 g neomycin sulfate and 1 g erythromycin base at 1 p.m., 2 p.m., and 11 p.m. on the day preceding surgery.^{2 3 6} Alternatively, give 2 g neomycin sulfate and 2 g metronidazole at 7 p.m. and 11 p.m. on the day preceding surgery.³

Begin a minimum residue or clear liquid diet 1–3 days before colorectal surgery with appropriate catharsis.^{2 3 6}

Hypercholesterolemia†

Oral

0.5–2 g daily.^{16 25} Do not use for long-term treatment.¹³

Prescribing Limits

Adults

Hepatic Encephalopathy

Chronic Hepatic Encephalopathy

Oral

Maximum: 4 g daily.^{1 2}

Special Populations

Hepatic Impairment

No specific dosage recommendations at this time other than those for patients with hepatic encephalopathy.^{1 2 a}

Renal Impairment

Reduce dosage or discontinue drug in patients with renal impairment.¹

Some clinicians recommend that doses be given every 6 hours in those with GFR >50 mL/minute, every 12–18 hours in those with GFR 10–50 mL/minute, or every 18–24 hours in those with GFR <10 mL/minute.²⁴

Geriatric Patients

Select dosage with caution and closely monitor renal function because of age-related decreases in renal function.^{1 2}

Cautions for Neomycin

Contraindications

• History of hypersensitivity or serious toxic reactions to neomycin or other aminoglycosides.^{1 2}

• Intestinal obstruction.^{1 2}

• Inflammatory or ulcerative GI disease; may enhance GI absorption of neomycin.^{1 2}

Warnings/Precautions

Warnings

Neurotoxicity and Ototoxicity

Patients receiving aminoglycosides should be under close clinical observation because of possible ototoxicity.^{1 2}

Vestibular and permanent bilateral auditory ototoxicity occurs most frequently in those with past or present history of renal impairment, those receiving other ototoxic drugs, and those who receive high dosages or prolonged treatment.^{1 2}

Perform serial, vestibular, and audiometric tests, if feasible, in patients old enough to be tested, particularly in high-risk patients.^{1 2}

Perform tests of the vestibulocochlearis nerve (eighth cranial nerve) function prior to and periodically during neomycin therapy.^{1 2}

Numbness, skin tingling, muscle twitching, and convulsions also may be signs of neurotoxicity.^{1 2}

Risk of hearing loss continues after drug withdrawal.^{1 2}

Some aminoglycosides have caused fetal ototoxicity when administered to pregnant women.^{1 2} (See Pregnancy under Cautions.)

Nephrotoxicity

Patients receiving aminoglycosides should be under close clinical observation because of possible nephrotoxicity.^{1 2} Renal function should be assessed prior to therapy and daily, or more frequently, during therapy.^{1 2}

Nephrotoxicity occurs most frequently in those with past or present history of renal impairment, those receiving other nephrotoxic drugs, and those who receive high dosage or prolonged treatment.^{1 2}

Monitor urine for increased protein excretion, decreased specific gravity, and the presence of cells and casts.^{1 2} Obtain Cl_cr, S_cr, and/or BUN at the onset of therapy and periodically during therapy.^{1 2}

Decrease dosage or discontinue drug if renal insufficiency develops.^{1 2}

Neuromuscular Blockade

Neuromuscular blockade and respiratory paralysis reported following oral neomycin.^{1 2}

Possibility of neuromuscular blockade should be considered, especially in patients receiving anesthetics or neuromuscular blocking agents (e.g., tubocurarine, succinylcholine, decamethonium) or in those receiving massive transfusions of citrate-anticoagulated blood.^{1 2}

Calcium salts may reverse neuromuscular blockade, but mechanical respiratory assistance may be necessary.^{1 2}

Sensitivity Reactions

Hypersensitivity

Serious and occasionally fatal hypersensitivity reactions, including anaphylaxis, reported with aminoglycosides.^{c d e f g h i i j k l m n}

Cross-sensitivity

Cross-sensitivity occurs among the aminoglycosides.^{1 2}

General Precautions

Selection and Use of Anti-infectives

To reduce development of drug-resistant bacteria and maintain effectiveness of neomycin and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.²

When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing.² In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.²

Topical Instillation

Quickly and almost totally absorbed from body surfaces (except the urinary bladder) after local irrigation or intraoperative topical application in association with medical procedures; neurotoxicity, nephrotoxicity, neuromuscular blockade, or respiratory paralysis may occur, even with minute quantities of neomycin, regardless of renal function.^{1 2}

Neuromuscular Disorders

Use with caution in patients with neuromuscular disorders such as myasthenia gravis or parkinsonism; may aggravate muscle weakness because of potential curare-like effect on the neuromuscular junction.^{1 2}

Superinfection

Possible emergence and overgrowth of nonsusceptible bacteria or fungi.^{1 2} Institute appropriate therapy if superinfection occurs.^{1 2}

Malabsorption Syndrome

May produce a malabsorption syndrome for a variety of substances including fat, nitrogen, cholesterol, carotene, glucose, xylose, lactose, sodium, calcium, cyanocobalamin, and iron.^{1 2} Usually reversible and dose-related; occurs most frequently in prolonged therapy or at high dosage (i.e., 12 g daily).^{1 2 13 23}

Specific Populations

Pregnancy

Category D.^{1 2}

Possibility of fetal harm if administered to a pregnant woman.^{1 2} Complete, irreversible, bilateral congenital deafness reported when another aminoglycoside (i.e., streptomycin) was used during pregnancy.^{1 2}

Lactation

IM neomycin is distributed into milk in cows; not known whether distributed into human milk.^{1 2} Discontinue nursing or the drug.^{1 2}

Pediatric Use

Safety and efficacy not established in children <18 years of age.^{1 2}

If neomycin is considered necessary in children <18 years of age^†, use with caution ^{1 2} and do not treat for >2 weeks^{1 2} since GI absorption may occur.^{1 2}

Risk of toxicity is increased in premature infants and neonates^†.^{1 2}

Geriatric Use

Increased risk of toxicity; use with caution and closely monitor renal function.^{1 2}

When assessing renal function in geriatric patients, Cl_cr may be more useful than BUN or S_cr.^{1 2}

Renal Impairment

Patients with renal impairment are at higher risk of nephrotoxicity and ototoxicity.^{1 2}

Patients with renal insufficiency may develop toxic blood concentrations unless doses are properly regulated.^{1 2}

Common Adverse Effects

Nausea,^{1 2} vomiting,^{1 2} diarrhea,^{1 2} abdominal cramps.^{13 23}

Drug Interactions

Neurotoxic, Ototoxic, or Nephrotoxic Drugs

Concomitant or sequential use with other drugs that have neurotoxic, ototoxic, or nephrotoxic effects may result in additive toxicity and should be avoided, if possible.^{1 2}

Because of the possibility of an increased risk of ototoxicity due to additive effects or altered serum and tissue aminoglycoside concentrations, do not use concurrently with potent diuretics.^{1 2}

Specific Drugs

Neomycin Pharmacokinetics

Absorption

Bioavailability

Poorly absorbed from the GI tract;^{26 29} about 3% of an oral dose is absorbed.^{1 2 21 22} Damaged or inflamed mucosa may increase GI absorption.²⁹

Rapidly and almost totally absorbed from body surfaces (except the urinary bladder) after local irrigation or intraoperative topical application in association with medical procedures.^{1 2}

Plasma Concentrations

In adults, a single 4-g oral dose produced peak plasma concentrations of 2.5–6.1 mcg/mL at 1–4 hours after the dose.²¹

Distribution

Extent

Distributed in low concentrations in intestinal wall and muscles.¹⁹

Distributed into milk in animals; not known whether distributed into human milk.^{1 2}

Plasma Protein Binding

0–30%.^{1 2}

Elimination

Elimination Route

Excreted principally in feces (97%) as unchanged drug^{1 2 13 26} and in urine (1%).^{13 21 22}

Removed by hemodialysis.^{1 2}

Half-life

Adults with normal renal function: 2–3 hours.^{23 24 29}

Severe renal impairment: 12–24 hours.²⁴

Stability

Storage

Oral

Tablets

20–25°C in tight container.²

Oral Solution

15–30°C.¹

Actions and Spectrum

• Usually bactericidal.^{1 2 b}

• Inhibits protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits.^b

• Following oral administration, rapidly suppresses growth of most intestinal bacteria; these are replaced by nonpathogenic yeasts and, occasionally, resistant strains of Enterobacter aerogenes.^{1 2} Suppression persists for 48–72 hours after the dose.^{1 2}

• In vitro spectrum of activity includes many gram-negative aerobic bacteria and some aerobic gram-positive bacteria.^{1 2} Inactive against fungi,^b viruses,^b and most anaerobic bacteria.^{1 2 b}

• Gram-negative aerobes: Active in vitro against Enterobacter, Escherichia coli, and Klebsiella.^{1 2}

• Partial cross-resistance occurs between neomycin and other aminoglycosides.^b

Advice to Patients

• Advise patients that antibacterials (including neomycin) should only be used to treat bacterial infections and not be used to treat viral infections (e.g., the common cold).²

• Importance of completing full course of therapy, even if feeling better after a few days.²

• Advise patients that skipping doses or not completing the full course of therapy may decrease effectiveness and increase the likelihood that bacteria will develop resistance and will not be treatable with neomycin or other antibacterials in the future.²

• Advise patients of the risk of toxic effects on the eighth nerve, including partial or total deafness.^{1 2} Inform patients that the possibility of acute toxicity is increased in premature infants and neonates.^{1 2}

• Importance of informing clinician if there is evidence of ototoxicity (dizziness, vertigo, tinnitus, roaring in the ears, hearing loss), other neurotoxicity (numbness, skin tingling, muscle twitching, seizures), or nephrotoxicity (e.g., decreased urine output).^{1 2}

• Importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.^{1 2}

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^{1 2}

• Importance of advising patients of other important precautionary information.^{1 2} (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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