Tobramycin (0.3% w/v) is an ophthalmic solution containing a potent aminoglycoside antibiotic. It is bactericidal and is primarily used for the treatment of external ocular infections caused by susceptible strains of bacteria, particularly Pseudomonas aeruginosa, which is a major concern in the Indian context due to high rates of infection and resistance. It is a first-line agent for bacterial keratitis and blepharitis.
Adult: For mild to moderate infections: Instill 1 or 2 drops into the affected eye(s) every 4 to 6 hours. For severe infections: Instill 2 drops every hour initially, reducing frequency as infection improves.
Note: 1. Wash hands before use. 2. Tilt head back, pull lower eyelid down to form a pouch. 3. Instill prescribed number of drops. 4. Close eyes gently for 1-2 minutes, applying gentle pressure to the nasolacrimal duct (inner corner of eye) to minimize systemic absorption. 5. Do not touch dropper tip to any surface to avoid contamination. 6. Wait at least 5-10 minutes before instilling any other ophthalmic medication.
Tobramycin binds irreversibly to the bacterial 30S ribosomal subunit. This binding interferes with the initiation complex, misreads mRNA, and causes premature termination of protein synthesis, leading to bacterial cell death.
Pregnancy: Category D (US FDA). There is positive evidence of human fetal risk (ototoxicity, nephrotoxicity from systemic use), but the benefits may outweigh risks in serious infections. For topical ophthalmic use, risk is low but should be used only if clearly needed. Consult an ophthalmologist and gynecologist.
Driving: May cause transient blurring of vision after instillation. Patients should not drive or operate machinery until vision clears.
| Other Aminoglycosides (e.g., Gentamicin, systemic) | Additive risk of nephrotoxicity and ototoxicity. | Major |
| Neuromuscular Blocking Agents (e.g., Succinylcholine, Atracurium) | Enhanced neuromuscular blockade, leading to respiratory depression. | Major |
| Loop Diuretics (e.g., Furosemide, Ethacrynic acid) | Additive risk of ototoxicity. | Major |
| Cephalosporins (systemic) | Potential additive nephrotoxicity. | Moderate |
| Vancomycin (systemic) | Increased risk of nephrotoxicity. | Moderate |
| Other Topical Ophthalmic Agents | Physical or chemical incompatibility. Administer at least 5-10 minutes apart. | Minor |