Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
BACITRACIN-NEOMYCIN-POLYMYXIN vs BETHKIS
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Bacitracin inhibits bacterial cell wall synthesis by interfering with dephosphorylation of the lipid carrier that transports peptidoglycan precursors. Neomycin and polymyxin B are aminoglycoside and polypeptide antibiotics, respectively; neomycin binds to the 30S ribosomal subunit, causing misreading of m RNA and inhibiting protein synthesis, while polymyxin B disrupts bacterial cell membrane integrity by interacting with lipopolysaccharides and phospholipids, leading to increased permeability and cell death.
Tobramycin, an aminoglycoside antibiotic, binds to the 30S ribosomal subunit, causing misreading of m RNA and inhibiting protein synthesis, leading to bacterial cell death.
Treatment of superficial bacterial infections of the skin and mucous membranes (e.g., wounds, burns, impetigo, folliculitis),Prophylaxis of minor skin abrasions and wounds to prevent infection,Off-label: Use in conjunctival irrigation or ophthalmic infections (as combination ophthalmic preparations)
Management of cystic fibrosis patients with Pseudomonas aeruginosa infection
Apply topically to affected area 2-5 times daily.
4 IU/kg (1 mg/kg) intramuscularly or subcutaneously once weekly for 4 weeks, then a maintenance dose of 2 IU/kg (0.5 mg/kg) once weekly.
Bacitracin: 1.5 hours (prolonged in renal impairment); Neomycin: 2-3 hours (accumulates with renal dysfunction); Polymyxin B: 6-9 hours (increased in renal impairment).
Terminal elimination half-life 2-3 hours in patients with normal renal function; prolonged to 20-40 hours in severe renal impairment (Cr Cl <30 m L/min).
Not extensively metabolized. Systemic absorption from topical application is minimal; absorbed drug may undergo hepatic metabolism or be excreted renally unchanged.
Primarily excreted unchanged in urine via glomerular filtration; minimal hepatic metabolism.
Bacitracin: primarily renal (>90% unchanged); Neomycin: renal (30-50% unchanged) with non-renal clearance; Polymyxin: renal excretion of parent drug (60-80% unchanged) with some biliary and fecal elimination.
Primarily renal excretion of unchanged drug via glomerular filtration; ~90% of absorbed dose excreted in urine within 24 hours; biliary/fecal elimination <5%.
Bacitracin: <10% bound to plasma proteins; Neomycin: 0-30% bound; Polymyxin B: 50-70% bound, primarily to alpha-1-acid glycoprotein and lipoproteins.
Low protein binding: 10-20%; primarily binds to albumin.
Bacitracin: 0.3 L/kg (confined to extracellular fluid); Neomycin: 0.2-0.3 L/kg (low tissue penetration except renal cortex); Polymyxin B: 0.7-1.0 L/kg (extensive tissue binding).
0.2-0.4 L/kg; distributes primarily into extracellular fluid; limited intracellular penetration.
Oral: negligible (<1%) for all three components; topical: minimal systemic absorption via intact skin (<0.5%); ophthalmic/otic: minimal absorption via mucosal surfaces.
Inhalation: ~50-60% of nominal dose reaches systemic circulation; oral: negligible (<1% due to poor gastrointestinal absorption).
No systemic absorption; no dosage adjustment required.
No dose adjustment required for renal impairment. Not removed by hemodialysis.
No systemic absorption; no dosage adjustment required.
No dose adjustment recommended for mild to moderate hepatic impairment (Child-Pugh A or B). Use with caution in severe hepatic impairment (Child-Pugh C) due to lack of data.
Apply topically to affected area 2-5 times daily; same as adult dose.
Weight-based dosing: 4 IU/kg (1 mg/kg) intramuscularly or subcutaneously once weekly for 4 weeks, then 2 IU/kg (0.5 mg/kg) once weekly. Safety and efficacy in children <18 years not established.
Apply topically to affected area 2-5 times daily; same as adult dose.
No specific dose adjustments recommended. Use with caution due to potential age-related decline in renal and hepatic function. Monitor for adverse effects.
Not applicable for topical formulations. However, systemic use of bacitracin (rare) may cause nephrotoxicity and anaphylactic reactions. Neomycin may cause ototoxicity and nephrotoxicity with systemic absorption.
Risk of nephrotoxicity and ototoxicity; monitor renal function and hearing during therapy.
Prolonged use may result in overgrowth of nonsusceptible organisms including fungi.,Topical use may cause allergic contact dermatitis, especially with neomycin.,Avoid application to large areas, open wounds, or damaged skin due to potential systemic absorption and toxicity.,Use with caution in patients with renal impairment or pre-existing hearing loss (neomycin component).,Ototoxicity and nephrotoxicity may occur if significant systemic absorption occurs.
Nephrotoxicity, ototoxicity (vestibular and auditory), neuromuscular blockade, hypersensitivity, superinfection.
Hypersensitivity to any component (bacitracin, neomycin, polymyxin B) or other aminoglycosides/polypeptide antibiotics.,Ophthalmic use in eyes with corneal abrasions or perforation (relative).,Known history of neomycin-associated ototoxicity or nephrotoxicity.
Hypersensitivity to tobramycin or other aminoglycosides.
No significant food interactions; topical application minimizes systemic absorption. No dietary restrictions.
No specific food interactions. Maintain adequate hydration; avoid excessive salt intake if concurrent diuretics are used.
Bacitracin-Neomycin-Polymyxin is a topical combination with negligible systemic absorption; thus, fetal risk is minimal. No known teratogenic effects reported; animal studies for individual components show no fetal harm at systemic doses. However, neomycin has theoretical risk of ototoxicity if systemically absorbed, but topical use is considered low risk. FDA Pregnancy Category C for components, but topical use deemed safe.
Insufficient human data; animal studies show no teratogenic effects at doses up to 4 times the human dose. Risk cannot be ruled out; use only if clearly needed.
Minimal systemic absorption after topical application; excretion into breast milk is unlikely. M/P ratio not determined; safe for use during breastfeeding if applied to small areas and not to open wounds.
Unknown if excreted in human breast milk; M/P ratio not available. Caution advised due to risk of infant bowel flora alteration and potential for tobramycin-related ototoxicity or nephropathy.
No dosing adjustments necessary for pregnancy. Pharmacokinetic changes due to pregnancy (e.g., increased skin blood flow, hydration) are not clinically significant for this topical combination. Standard topical application is appropriate.
No specific dose adjustments recommended; pharmacokinetics may be altered due to increased volume of distribution and GFR; monitor serum levels and adjust to maintain therapeutic trough <2 mcg/m L.
Triple antibiotic ointment (bactiracin-neomycin-polymyxin) is first-line for prophylaxis of minor skin infections; avoid use on large areas, deep wounds, or burns due to risk of systemic absorption and nephrotoxicity. Neomycin carries high risk of allergic contact dermatitis; consider alternative in patients with known hypersensitivity. Topical use only; not for ophthalmic or intranasal application due to polymyxin ocular toxicity. Synergistic coverage includes Gram-positive (bacitracin), Gram-negative (polymyxin), and broad-spectrum (neomycin).
Administer via inhalation only using a suitable nebulizer; do not mix with other drugs in the nebulizer. Monitor for bronchospasm; consider pretreatment with a bronchodilator in patients with reactive airway disease. Assess renal function before and during therapy due to potential nephrotoxicity. Obtain audiometric testing at baseline and periodically due to ototoxicity risk. Avoid concurrent use of loop diuretics or other nephrotoxic drugs. Trough serum tobramycin concentrations should be measured after 2–3 doses when systemic absorption is suspected.
Apply a thin layer to clean, minor cuts, scrapes, or burns 1-3 times daily.,Do not use on large body areas, deep puncture wounds, animal bites, or serious burns.,Stop use and consult doctor if rash, irritation, or signs of infection (worsening redness, swelling, pus) develop.,Avoid use on eyes, nose, or mouth; if contact occurs, rinse thoroughly with water.,Tell your doctor if you have kidney problems or are allergic to any of the ingredients (bacitracin, neomycin, polymyxin B).
Use Bethkis exactly as prescribed; do not skip doses or double up.,Do not swallow or inject Bethkis; it is for inhalation only.,Use a nebulizer with a mouthpiece; do not use a face mask unless necessary.,Store vials in the refrigerator; protect from light.,Clean and disinfect the nebulizer after each use.,Report hearing loss, ringing in the ears, dizziness, or changes in urine output immediately.,Avoid other inhaled medications within 30 minutes of Bethkis unless directed.,Inform your healthcare provider of all other medications, especially diuretics and other antibiotics.
"The therapeutic efficacy of Picosulfuric acid can be decreased when used in combination with Bacitracin."
"Bacitracin may increase the nephrotoxic activities of Colistimethate."
"Bacitracin may increase the nephrotoxic activities of Streptomycin."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about BACITRACIN-NEOMYCIN-POLYMYXIN vs BETHKIS, answered by our medical review team.
BACITRACIN-NEOMYCIN-POLYMYXIN is a Aminoglycoside Antibiotic that works by Bacitracin inhibits bacterial cell wall synthesis by interfering with dephosphorylation of the lipid carrier that transports peptidoglycan precursors. Neomycin and polymyxin B are aminoglycoside and polypeptide antibiotics, respectively; neomycin binds to the 30S ribosomal subunit, causing misreading of m RNA and inhibiting protein synthesis, while polymyxin B disrupts bacterial cell membrane integrity by interacting with lipopolysaccharides and phospholipids, leading to increased permeability and cell death.. BETHKIS is a Aminoglycoside Antibiotic that works by Tobramycin, an aminoglycoside antibiotic, binds to the 30S ribosomal subunit, causing misreading of m RNA and inhibiting protein synthesis, leading to bacterial cell death.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between BACITRACIN-NEOMYCIN-POLYMYXIN and BETHKIS depend on the specific clinical indication. These are both Aminoglycoside Antibiotic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of BACITRACIN-NEOMYCIN-POLYMYXIN is: Apply topically to affected area 2-5 times daily.. The standard adult dose of BETHKIS is: 4 IU/kg (1 mg/kg) intramuscularly or subcutaneously once weekly for 4 weeks, then a maintenance dose of 2 IU/kg (0.5 mg/kg) once weekly.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between BACITRACIN-NEOMYCIN-POLYMYXIN and BETHKIS in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. BACITRACIN-NEOMYCIN-POLYMYXIN is classified as Category A/B. Bacitracin-Neomycin-Polymyxin is a topical combination with negligible systemic absorption; thus, fetal risk is minimal. No known teratogenic effects reported; animal studies for i. BETHKIS is classified as Category C. Insufficient human data; animal studies show no teratogenic effects at doses up to 4 times the human dose. Risk cannot be ruled out; use only if clearly needed.. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.