Tobrex®
Tobramycin 0.3% · ophthalmic solution
Antibiotic
Approved uses
Bacterial conjunctivitis
1 or 2 drops into the affected eye(s) every 4 hours (mild to moderate disease)
About 90% clinical cure by day 7, and cure sustained to day 12 after a 7-day course.
Severe external ocular infection
2 drops into the affected eye(s) hourly until improvement, then reduce frequency before discontinuing
OFF-LABELNot in the FDA label for this product
Bacterial keratitis, as fortified tobramycin 1.3% with cefazolin 5%
Fortified tobramycin 1.3%: 1 to 2 drops every 30 minutes for 6 hours, then hourly for the rest of day 1, hourly on days 2 to 3, every 2 hours on days 4 to 5, every 4 hours on days 6 to 14, with cefazolin 5% instilled 5 to 15 minutes after each dose
RCT · n=324 · compounded
Randomized, double-masked, multicenter trial in 324 patients (176 culture-positive evaluable): fortified tobramycin plus cefazolin achieved 86.2% clinical success versus 91.5% for ciprofloxacin 0.3% monotherapy (P = 0.34, no significant difference), with significantly more discomfort on the fortified regimen (P = 0.01). The regimen studied was a compounded 1.3% concentration, not the commercial 0.3% solution.
Antibacterial cover after penetrating keratoplasty
1 drop QID until complete re-epithelialization (with topical dexamethasone)
RCT · n=46 · not prophylaxis
Prospective single-center randomized trial, 46 patients: mean time to complete re-epithelialization was 4.14 ± 1.17 days with Tobrex versus 4.13 ± 1.82 days with azithromycin (P = 0.89), and superficial punctate keratitis scores were similar (1.39 versus 1.34). No infection occurred in either arm, so the trial speaks to healing and tolerance, not to prophylactic efficacy.
Contraindications
Known hypersensitivity to tobramycin or any component of the formulation.
Available FormsOphthalmic solution, 2 mL, 5 mL dropper bottles, 0.3% (3 mg/mL)
Mechanism of ActionAminoglycoside that binds the bacterial 30S ribosomal subunit and disrupts protein translation, killing susceptible organisms. In vitro coverage includes staphylococci (penicillin-resistant strains included), some streptococci, Pseudomonas aeruginosa and other gram-negatives; some gentamicin-resistant isolates remain susceptible.
Warnings & Precautions
- Topical ophthalmic use only: Not for injection into the eye.
- Aminoglycoside hypersensitivity: Reactions range from local effects to generalized erythema, itching, urticaria, skin rash, anaphylaxis, anaphylactoid or bullous reactions; discontinue if sensitivity occurs.
- Aminoglycoside cross-sensitivity: Sensitivity to other aminoglycosides may occur; discontinue and institute appropriate therapy.
- Superinfection: Prolonged use may cause overgrowth of nonsusceptible organisms, including fungi.
- Corneal epithelial toxicity: In a rabbit wound-healing model, tobramycin, gentamicin and chloramphenicol were the most toxic of eight topical antibiotic solutions tested, and fortified preparations did not appear more toxic than the 0.3% solutions; the authors concluded topical antibiotics should not be assumed innocuous when treating an epithelial defect.
- Systemic aminoglycoside class effects: Neurotoxicity, ototoxicity and nephrotoxicity have occurred with systemic aminoglycoside therapy, which may also aggravate muscle weakness in neuromuscular disorders such as myasthenia gravis or Parkinson disease.
- Contact lens wear: Not advised while signs and symptoms of bacterial ocular infection are present.
Common Side Effects
- Ocular: Hypersensitivity and localized ocular toxicity, including lid itching and swelling and conjunctival erythema; fewer than 3 of 100 treated patients.
- Systemic: Anaphylactic reaction, Stevens-Johnson syndrome, erythema multiforme; postmarketing reports.
Pregnancy & LactationPregnancy: Reproduction studies in 3 animal species at up to 33 times the human systemic dose showed no impaired fertility and no fetal harm; no adequate, well-controlled studies in pregnant women, so use only if clearly needed.
Lactation: Given the potential for adverse reactions in nursing infants, decide between discontinuing nursing and discontinuing the drug.
Pediatric UseNot established below age 2 months.