Generic Name

Neosporin

Mechanism

• Bacitracin: Inhibits bacterial cell wall synthesis by interfering with the dephosphorylation of bacitracin‑binding protein, thereby preventing peptidoglycan cross‑linking.
• Polymyxin B: Disrupts the outer membrane of Gram‑negative bacteria by binding to lipopolysaccharides and phospholipids, leading to increased cell membrane permeability and cell death.
• Neomycin: Binds sub‑unit 1 of the bacterial 30S ribosomal subunit, causing misreading of mRNA and inhibition of protein synthesis.

Collectively, these agents have broad Gram‑positive and Gram‑negative coverage, reducing the risk of infection development in minor wounds.

Pharmacokinetics

• Absorption: Minimal systemic absorption due to topical application; negligible plasma concentrations.
• Distribution: Localized to the wound bed; not systemically distributed.
• Metabolism & Elimination: No significant metabolism; excretion is negligible owing to limited absorption.

Typical serum concentrations remain below levels that would induce systemic toxicity.

Indications

• Post‑procedural care and superficial cuts, lacerations, abrasions, and puncture wounds.
• Minor burns  1 cm, or ophthalmic/ear/respiratory tract infections.*

Contraindications

• Allergy to any component (bacitracin, polymyxin B, neomycin).
• Known penicillin/streptomycin cross‑reactive allergies may predispose to hypersensitivity.
• Open, necrotic, or heavily contaminated wounds – insufficient penetration.
• Use in the ocular area may cause keratitis if accidental contamination occurs.
• Neuromuscular disorders – neomycin can exacerbate neuromuscular blockade.

Warnings:
• Contact dermatitis or anaphylactoid reactions are possible.
• Systemic absorption is unlikely but can occur in large surface areas or prolonged use, potentially leading to ototoxicity or nephrotoxicity.

Dosing

• Apply 1–2 mg of ointment to the wound surface.
• Frequency: 2–3 times daily or after cleaning/rinsing the wound.
• Duration: Stop once the wound has healed or after 7–10 days if healing is slower.
• Technique: Apply a thin layer and cover with a sterile dressing if needed.
• Storage: Keep at room temperature, away from moisture and direct sunlight.

Do not exceed 10 g per day in a single patient area.

Adverse Effects

Monitoring

• Cutaneous response: Observe for signs of infection (increased erythema, purulent drainage, unexplained pain).
• Allergic signs: Watch for rash, swelling, or respiratory distress.
• Systemic signs: Hearing changes, renal function decline (rare) – counsel patients to report tinnitus or decreased urine output.
• Duration of use: Ensure therapy does not exceed 10 days unless under physician guidance.

Clinical Pearls

• Use sparingly – a pea‐size amount is often adequate; excess ointment provides no additional benefit and may increase irritation.
• Avoid large surface area – especially in children, infants, or patients with compromised skin to minimize absorption.
• Wash hands after application – prevents inadvertent ingestion or ocular exposure.
• Alternate for allergic patients – use mupirocin or silver sulfadiazine for individuals with neomycin or bacitracin hypersensitivity.
• Do not use on open femur fractures or deep abscesses – systemic agents are required.
• Pre‑treatment evaluation – screen for aminoglycoside allergy, particularly in patients with a history of nephrotoxic drug exposure.

Key Takeaway: Neosporin’s broad topical coverage makes it a convenient first‑line agent for minor superficial wounds, but judicious use and awareness of contraindications are essential for safe therapy.