What is the active antibiotic ingredient in Tobrex (tobramycin)?

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Last updated: June 26, 2025View editorial policy

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From the FDA Drug Label

Tobramycin ophthalmic solution USP, 0.3% is a sterile topical ophthalmic antibiotic formulation prepared specifically for topical therapy of external ophthalmic infections. Each mL of tobramycin ophthalmic solution USP, 0.3% contains:Active: tobramycin 0.3 % (3 mg). Tobramycin is a water-soluble aminoglycoside antibiotic active against a wide variety of gram-negative and gram-positive ophthalmic pathogens.

The active antibiotic ingredient in Tobrex is tobramycin, an aminoglycoside antibiotic 1.

  • Key points:
    • Antibiotic class: Aminoglycoside
    • Active ingredient: Tobramycin
    • Concentration: 0.3% (3 mg/mL)

From the Research

Tobramycin is the active antibiotic ingredient in Tobrex, and it is an aminoglycoside antibiotic that works by binding to bacterial ribosomes and inhibiting protein synthesis, which kills susceptible bacteria. The most recent and highest quality study 2 supports the use of tobramycin in the treatment of bacterial eye infections, including conjunctivitis, keratitis, and corneal ulcers. Tobrex is typically available as an ophthalmic solution (0.3%) or ointment, and it is particularly effective against gram-negative organisms, including Pseudomonas aeruginosa, as well as some gram-positive bacteria.

Key Points to Consider

  • Tobramycin has a broad spectrum of activity, making it useful in controlling both superficial and deep infections of the eye and ocular adnexa 3.
  • The medication should be applied after washing hands thoroughly, and care should be taken to avoid touching the tip of the container to any surface to prevent contamination.
  • Patients should be aware that aminoglycosides like tobramycin can occasionally cause local irritation, and if severe reactions occur, they should contact their healthcare provider.
  • It is essential to complete the full course of treatment as prescribed, even if symptoms improve before completion.

Treatment and Administration

  • Tobrex is typically administered topically, and the dosage may vary depending on the specific condition being treated.
  • The most recent study 2 compared the safety and efficacy of a new enhanced viscosity ophthalmic formulation of tobramycin with the existing four times daily treatment regimen in patients with acute bacterial conjunctivitis, and found that the enhanced viscosity formulation was well tolerated and had equivalent efficacy to the established treatment regimen.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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