Bacitracin/Neomycin/Polymyxin B

Veterinary Form:

Triple Antibiotic Ophthalmic Ointment
(Bacitracin/Neomycin/Polymyxin B)
Also known as: BNP


Mycitracin (ophthalmic ointment), Trioptic-P, Vetropolycin, Neobacimyx

Human product: Neosporin Ophthalmic Solution uses gramicidin in place of bacitracin. They are virtually the same except that gramicidin is more soluble in water when using in a solution.


  • Veterinary ophthalmic ointment comes in 3.5 gm size tubes.


BNP: Bacitracin zinc, Neomycin sulfate, and Polymyxin B sulfate is a triple antibiotic combination ointment used for external bacterial infections of the eye.

Bacitracin zinc, rarely used systemically due to its nephrotoxic effects, but when used as an ophthalmic preparation does not penetrate the cornea in therapeutic amounts and causes no systemic effect. It is also nonirritating to the eye.

It is useful in the treatment of superficial infections caused by Gram-positive bacteria. A broader spectrum of antimicrobial activity occurs when combined with neomycin and polymyxin B in ophthalmic ointment.

Neomycin sulfate contained in the combination eye ointment has a broad antibacterial spectrum and a low index of allergenicity. It is an active topical sensitizer and can cause cross-sensitivity reactions to systemic use antibiotics that are chemically related to neomycin. It is effective when used in combination with bacitracin and polymyxin for treating superficial ocular infections involving the conjunctiva and cornea.

Polymyxin B sulfate has activity against Gram-negative bacteria. Hypersensitivity reactions to the topical Polymyxin are practically unheard of. An intact corneal epithelium prevents penetration into the eye, but in the presence of epithelial damage from abrasion or ulceration penetration is effective.

The combination of these three antibiotics provides a more effective bactericidal action against Gram-positive and Gram-negative bacteria infections of the eyes.


Used for superficial bacterial infections of the conjunctiva and eyelid, as prophylactic treatment for surgery, or as prophylactic treatment in the presence of corneal injuries.

Drug Interactions or Contraindications

  • Not recommended for long-term use due to possible overgrowth of non-susceptible organisms.
  • Do not use in infections where viral or fungal organisms are believed to be the cause.

Adverse Reactions

EENT: blurred vision, burning or stinging on instillation, lid itching or swelling, conjunctival redness

Other: overgrowth of non-susceptible organisms

Dosage Recommendations

Apply thin film to affected eye 2 to 3 times per day, or as directed by the vet. 12, 26


Apply thin film 4 times daily, and up to every 30 minutes in established corneal infections (under direction of a veterinarian).  27


Instillation of a triple antibiotic ophthalmic solution as directed by veterinarian.


  • Pet owners should be sure to wash hands before and after applying drops or ointment to a rat’s eye(s). Wipe excessive lacrimation (porphyrin around the eyes in rats) or debris from eye(s) before application. Do not touch tube opening to any surface, including eyes or hands. The tube opening is sterile, and if contaminated it could cause additional infection in the eye.
  • Do not use any tube where the ointment is discolored, or the solution has particles in it. Check expiration date.
  • Discontinue use, and contact veterinarian, if the following occurs: keratitis, redness, increased lacrimation, swelling of eye, or if rat starts to scratch eye in attempt to relieve itching.
  • Unopened ophthalmic ointment may be stored for up to a year at room temperature away from moisture and heat, or until expiration date.


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