Bacterial Ophthalmic Infections
Tobramycin ophthalmic ointment and ophthalmic solution are used for the topical treatment of superficial infections of the eye caused by susceptible bacteria.1, 2, 6
Although mild, acute bacterial conjunctivitis often resolves spontaneously without anti-infective treatment,135, 136, 137 topical ophthalmic anti-infectives may shorten the time to resolution and reduce severity and risk of complications.135, 136, 137, 141 Treatment of acute bacterial conjunctivitis generally is empiric and use of a broad-spectrum topical ophthalmic antibacterial usually is recommended;135, 136, 141 however, indiscriminate use of topical anti-infectives should be avoided.135, 141 In vitro staining and/or cultures of conjunctival material may be indicated in the management of recurrent, severe, or chronic purulent conjunctivitis or when acute conjunctivitis does not respond to initial empiric topical treatment.135, 136, 141
Because many forms of bacterial keratitis are associated with subsequent loss of vision as the result of corneal scarring or topographic irregularities and because untreated or severe bacterial keratitis may result in perforation of the cornea with the potential for endophthalmitis and possible loss of the eye, optimal management involves rapid evaluation and diagnosis, timely initiation of treatment, and appropriate follow-up.138 Treatment of community-acquired bacterial keratitis generally is empiric and use of a broad-spectrum topical ophthalmic antibacterial usually is recommended.138 Subconjunctival therapy with an appropriate anti-infective may be necessary if scleral spread or perforation is imminent.138 In vitro staining and/or cultures are indicated in the management of keratitis involving corneal infiltrates that are central, large, and extending to the middle to deep stroma; when keratitis is chronic or unresponsive to treatment with a broad-spectrum topical anti-infective; or when atypical features are present suggesting fungal, amebic, or mycobacterial infection.138
Topical ophthalmic preparations containing tobramycin in fixed combination with a corticosteroid (i.e., dexamethasone or loteprednol etabonate) are used in the management of corticosteroid-responsive ocular conditions when a corticosteroid is indicated and superficial bacterial ocular infection or risk of such infection exists.3, 4, 5, 10, 11
Ophthalmic corticosteroids may be indicated in inflammatory conditions of the palpebral and bulbar conjunctiva, cornea, and anterior segment of the globe where the inherent risk of corticosteroid use in certain infective conjunctivitides is accepted to obtain diminution in edema and inflammation.3, 4, 5, 10, 11 Ophthalmic corticosteroids also may be indicated in the treatment of chronic anterior uveitis and corneal injury from chemical, radiation, or thermal burns or penetration of foreign bodies.3, 4, 5, 10, 11
Although the manufacturers state that use of a fixed-combination ophthalmic preparation containing an anti-infective and a corticosteroid may be indicated in ocular inflammatory conditions when the risk of superficial ocular infection is high or when there is an expectation that potentially dangerous numbers of bacteria will be present in the eye,3, 4, 5, 10, 11 experts state that such preparations should be avoided in patients with bacterial conjunctivitis because of the risk of potentiating the infection.136
Clinicians should consider that use of fixed-combination ophthalmic preparations containing an anti-infective and a corticosteroid may mask the clinical signs of bacterial, fungal, or viral infections; prevent recognition of ineffectiveness of the anti-infective; and/or increase intraocular pressure.3, 4, 5, 10, 11
Tobramycin is applied topically to the eye as a 0.3% ophthalmic ointment2 or 0.3% ophthalmic solution.1, 6
Tobramycin also is commercially available in fixed combination with a corticosteroid (i.e., dexamethasone or loteprednol etabonate) for topical application to the eye as an ophthalmic ointment or suspension.3, 4, 5, 10, 11
Tobramycin ophthalmic preparations and fixed-combination ophthalmic preparations containing tobramycin and a corticosteroid are for topical ophthalmic use only ;1, 2, 3, 4, 5, 6, 10, 11 these preparations should not be injected directly into the eye.1, 2, 3, 4, 6, 11
Care should be taken to avoid contaminating the container tip with material from any source.1, 2, 3, 4, 5, 6, 10, 11
Fixed-combination ophthalmic suspensions containing tobramycin and a corticosteroid should be shaken well prior to use.3, 5, 10, 11
Bacterial Ophthalmic Infections
For the topical treatment of superficial bacterial ophthalmic infections in adults and children 2 months of age and older, a ribbon of tobramycin 0.3% ophthalmic ointment approximately 1.25 cm (½ inch) in length should be placed in the affected eye(s) 2 or 3 times daily.2 For severe infections, the ointment should be applied to the affected eye(s) every 3-4 hours initially.2
If tobramycin 0.3% ophthalmic solution is used for the topical treatment of superficial bacterial ophthalmic infections in adults and children 2 months of age or older, 1 or 2 drops of the ophthalmic solution should be instilled in the affected eye(s) every 4 hours.1, 6 For severe infections, 2 drops of the ophthalmic solution should be instilled in the affected eye(s) every hour initially.1, 6
When improvement occurs, dosage should be tapered by decreasing frequency of application until the drug is discontinued.1, 2, 6
The usual duration of topical anti-infective treatment for bacterial conjunctivitis is 5-10 days;135, 136, 141 some experts state that 5-7 days of such treatment usually is adequate for mild bacterial conjunctivitis.135
When the fixed-combination ophthalmic ointment containing tobramycin and dexamethasone (tobramycin 0.3% and dexamethasone 0.1%) is used in adults and children 2 years of age or older, a ribbon of the ointment approximately 1.25 cm (½ inch) in length should be placed into the conjunctival sac of the affected eye(s) up to 3 or 4 times daily.4
When the fixed-combination ophthalmic suspension containing tobramycin and dexamethasone (tobramycin 0.3% and dexamethasone 0.05% or tobramycin 0.3% and dexamethasone 0.1%) is used in adults and children 2 years of age or older, 1 or 2 drops of the ophthalmic suspension should be instilled into the conjunctival sac of the affected eye(s) every 4-6 hours.3, 10, 11 During the initial 24-48 hours, 1 or 2 drops of the ophthalmic suspension may be instilled into the affected eye(s) every 2 hours if necessary.3, 10, 11
When the fixed-combination ophthalmic suspension containing tobramycin and loteprednol etabonate (tobramycin 0.3% and loteprednol etabonate 0.5%) is used in adults, 1 or 2 drops of the suspension should be instilled into the conjunctival sac of the affected eye(s) every 4-6 hours.5 During the initial 24-48 hours, 1 or 2 drops of the ophthalmic suspension may be instilled into the affected eye(s) every 1-2 hours if necessary.5
If there is no improvement after 2 days of treatment with a fixed-combination ophthalmic preparation, the patient should be reevaluated.5, 10 After improvement occurs, dosage may be tapered gradually by decreasing the frequency of administration.3, 5, 10, 11 Care should be taken to not discontinue therapy prematurely.3, 5, 10, 11
The most frequent adverse reactions following topical application of tobramycin ophthalmic preparations are hypersensitivity and localized ocular toxicity, including itching and edema of the eyelid and conjunctival erythema.1, 2, 6 These reactions occur in 4% or less of patients receiving ophthalmic tobramycin.1, 2, 6 Punctate keratitis and increased lacrimation have also been reported following excessive topical application of tobramycin ophthalmic ointment or solution.1, 2
Sensitization to tobramycin may result from topical application.1, 2, 3, 4, 5, 6, 10, 11 Cross-allergenicity among the aminoglycosides has been demonstrated, and the possibility that patients who become sensitized to topical tobramycin may also be sensitive to other topical and/or systemic aminoglycosides should be considered.1, 2, 3, 4, 5, 6, 11
Precautions and Contraindications
Tobramycin ophthalmic ointment and ophthalmic solution are contraindicated in patients hypersensitive to the drug or any ingredients in the formulation.1, 2, 6
Fixed-combination ophthalmic preparations containing tobramycin and a corticosteroid (i.e., dexamethasone or loteprednol etabonate) are contraindicated in patients with known or suspected hypersensitivity to any ingredient in the formulation.3, 4, 10, 11 In addition, these fixed-combination preparations are contraindicated in patients with viral diseases of the cornea and conjunctiva, including epithelial herpes simplex keratitis (dendritic keratitis), vaccinia, and varicella, and in patients with mycobacterial infections of the eye or fungal diseases of ocular structures.3, 4, 5, 10, 11
If a sensitivity reaction occurs during topical tobramycin therapy, the drug should be discontinued and appropriate therapy initiated.1, 2, 3, 4, 5, 6, 11
Prolonged use of topical tobramycin may result in overgrowth of nonsusceptible organisms, including fungi.1, 2, 3, 4, 6, 11 If superinfection occurs, the drug should be discontinued and appropriate therapy initiated.1, 2, 3, 4, 6, 11
The manufacturers caution that ophthalmic ointments may delay corneal healing.2, 4
Contact lenses should not be worn during treatment3, 4, 5, 6, 10, 11 or when any signs or symptoms of bacterial ocular infection are present.2, 4, 6
Serious adverse reactions including ototoxicity and nephrotoxicity have occurred in patients receiving systemic tobramycin sulfate therapy. Although these effects have not been reported to date following topical use of tobramycin, the possibility of cumulative toxicity should be considered. If tobramycin is administered topically in conjunction with systemic aminoglycoside therapy, serum aminoglycoside concentrations should be monitored.1, 2, 3, 6, 10
Precautions Related to Use of Fixed Combinations Containing Corticosteroids
When ophthalmic preparations containing tobramycin in fixed combination with a corticosteroid (i.e., dexamethasone or loteprednol etabonate) are used, the usual cautions, precautions, and contraindications associated with the corticosteroid also must be considered.3, 4, 5, 10, 11
Initial prescriptions for fixed-combination ophthalmic preparations containing tobramycin and a corticosteroid and renewal prescriptions (beyond 8 g of ophthalmic ointment or beyond 20 mL of ophthalmic solution or suspension) should be made only after examining the patient with slit lamp microscopy and, when appropriate, fluorescein staining.3, 4, 5, 10, 11
Patients should be advised to contact a clinician if symptoms fail to improve after 2 days of treatment,5, 10 if pain develops,5 or if redness, pruritus, or inflammation becomes aggravated.5
Prolonged use of fixed-combination ophthalmic preparations containing a corticosteroid may result in glaucoma, with damage to the optic nerve, defects in visual acuity and fields of vision, and posterior subcapsular cataract formation.3, 4, 5, 10, 11 If an ophthalmic preparation containing a corticosteroid is used for 10 days or longer,5, 10 intraocular pressure should be routinely monitored, even though this may be difficult in children and uncooperative patients.3, 4, 5, 10, 11 Such preparations should be used with caution in patients with glaucoma and intraocular pressure should be checked routinely in such patients.4, 5, 10, 11
Use of fixed-combination ophthalmic preparations containing a corticosteroid after cataract surgery may delay healing and increase the incidence of bleb formation.3, 4, 5, 10, 11
Use of topical ophthalmic corticosteroids in patients with thin corneal and scleral tissue may result in perforation.3, 4, 5, 10, 11
Prolonged use of fixed-combination ophthalmic preparations containing a corticosteroid may suppress host responses and increase the risk of secondary ocular infections.3, 4, 5, 10, 11 Use of such preparations in patients with acute purulent conditions of the eye may mask infection or enhance existing infection.3, 4, 5, 10, 11
Use of ophthalmic preparations containing a corticosteroid may prolong the course and exacerbate severity of many viral infections of the eye (including herpes simplex).5, 10 Such preparations should be used with great caution in patients with herpes simplex.5, 10
The possibility of fungal infections of the cornea should be considered after prolonged use of ophthalmic preparations containing a corticosteroid.3, 4, 5, 10, 11 Fungal cultures should be taken when appropriate.5
Safety and efficacy of tobramycin ophthalmic ointment and ophthalmic solution have not been established in infants younger than 2 months of age.1, 2, 6
Safety and efficacy of fixed-combination ophthalmic preparations containing tobramycin and dexamethasone have not been established in children younger than 2 years of age.3, 4, 10, 11
Efficacy of the fixed-combination ophthalmic suspension containing tobramycin and loteprednol etabonate has not been established in pediatric patients.5
No overall differences in safety or efficacy of tobramycin ophthalmic preparations have been observed between geriatric and younger patients.1, 2, 3, 4, 5, 6, 10, 11
Mutagenicity and Carcinogenicity
Studies have not been performed to date to evaluate the mutagenic or carcinogenic potential of tobramycin.
Pregnancy, Fertility, and Lactation
Animal reproduction studies using systemic tobramycin dosages up to 33 times the usual human systemic dosage have not revealed evidence of impaired fertility or harm to the fetus.1, 2, 6
There are no controlled studies to date using tobramycin ophthalmic preparations in pregnant women.1, 2, 3, 4, 5, 6, 10, 11
Tobramycin ophthalmic ointment and ophthalmic solution should be used during pregnancy only if clearly needed.1, 2, 6
Fixed-combination ophthalmic preparations containing tobramycin and a corticosteroid (i.e., dexamethasone or loteprednol etabonate) should be used during pregnancy only if potential benefits justify potential risks to the fetus.3, 4, 5, 10, 11
A decision should be made whether to discontinue nursing or discontinue tobramycin ophthalmic preparations, taking into account the importance of the drug to the woman.1, 2, 6
The manufacturers state that caution is advised if fixed-combination ophthalmic preparations containing tobramycin and a corticosteroid are used in nursing women.3, 4, 5, 10, 11
Tobramycin is usually bactericidal in action. Although the exact mechanism of action has not been fully elucidated, the drug appears to inhibit protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits.
In general, tobramycin is active against many aerobic gram-negative bacteria and some aerobic gram-positive bacteria. The drug is inactive against Chlamydia, fungi, viruses, and most anaerobic bacteria.
Tobramycin is active in vitro against some gram-positive bacteria, including Staphylococcus aureus , S. epidermidis , Streptococcus pneumoniae , and group A β-hemolytic streptococci.1, 2, 6
Tobramycin also is active in vitro against some gram-negative bacteria, including Acinetobacter calcoaceticus , Haemophilus influenzae , H. aegyptius , Enterobacter aerogenes , Escherichia coli , Klebsiella pneumoniae , Moraxella lacunata , Morganella morganii , Neisseria , Proteus mirabilis , P. vulgaris , and Pseudomonas aeruginosa .1, 2, 6
Natural and acquired resistance to tobramycin has been demonstrated in both gram-negative and gram-positive bacteria. Tobramycin resistance may be due to decreased permeability of the bacterial cell wall, alterations in the ribosomal binding site, or the presence of a plasmid-mediated resistance factor which is acquired via conjugation. Plasmid-mediated resistance enables the resistant bacteria to enzymatically modify the drug by acetylation, phosphorylation, or adenylylation and can be transferred between organisms of the same or different species. Resistance to other aminoglycosides and several other anti-infectives (e.g., chloramphenicol, sulfonamides, tetracyclines) may be transferred on the same plasmid.
Partial cross-resistance occurs between tobramycin and other aminoglycosides.
Studies in rabbits suggest that tobramycin is absorbed into the aqueous humor following topical instillation onto the eye of a solution of the drug containing 3 mg/mL; it is not known whether tobramycin is absorbed into the vitreous humor following topical instillation. Absorption of tobramycin is greatest when the cornea is abraded. The manufacturer states that topically administered tobramycin ophthalmic solution is cleared from the surface of the eye in approximately 15-30 minutes.
Information on absorption of tobramycin following topical application to the eye of an ophthalmic ointment containing the drug is not currently available.
In one study in rabbits with normal corneas, peak concentrations of tobramycin were attained in the cornea and aqueous humor 1-2 hours after topical instillation of a solution of the drug containing 3 mg/mL. Within 1-2 hours, peak cornea concentrations of tobramycin in these rabbits averaged 4.5 mcg/g of cornea and peak aqueous humor concentrations averaged 0.28 mcg/mL.
Tobramycin is an aminoglycoside antibiotic derived from Streptomyces tenebrarius .12 Tobramycin occurs as a white to off-white, hygroscopic powder and is freely soluble in water and very slightly soluble in alcohol.
Tobramycin is commercially available for topical ophthalmic use as an ophthalmic ointment2 or ophthalmic solution1, 6 containing 0.3% tobramycin.1, 2, 6 Tobramycin also is commercially available for topical ophthalmic use in fixed combination with a corticosteroid (i.e., dexamethasone or loteprednol etabonate).3, 4, 5, 10, 11
Tobramycin 0.3% ophthalmic ointment is a sterile ointment containing the drug in a mineral oil and petrolatum ointment base.2 The ophthalmic ointment contains chlorobutanol as a preservative.2
Tobramycin 0.3% ophthalmic solution is a sterile, isotonic solution of the drug with a pH of 7-8.1, 6 The ophthalmic solution contains benzalkonium chloride as a preservative.1, 6
The fixed combination of tobramycin and dexamethasone is commercially available as a sterile ophthalmic ointment (tobramycin 0.3% and dexamethasone 0.1%)4 or as a sterile ophthalmic suspension (tobramycin 0.3% and dexamethasone 0.05%; tobramycin 0.3% and dexamethasone 0.1%).3, 10, 11 The fixed-combination ophthalmic ointment contains tobramycin and dexamethasone in a mineral oil and white petrolatum ointment base and contains chlorobutanol as a preservative.4 The fixed-combination ophthalmic suspension contains benzalkonium chloride as a preservative.3, 10, 11
The fixed-combination ophthalmic suspension of tobramycin and loteprednol etabonate (tobramycin 0.3% and loteprednol etabonate 0.5%) is a sterile suspension that is essentially isotonic (tonicity of 260-320 mOsm/kg), has a pH of 5.7-5.9, and contains benzalkonium chloride as a preservative.5
Tobramycin 0.3% ophthalmic ointment should be stored at 2-25°C.2
Depending on the manufacturer, tobramycin 0.3% ophthalmic solution should be stored at 2-256 or 20-25°C1 and protected from excessive heat.1
The fixed-combination ophthalmic ointment containing tobramycin 0.3% and dexamethasone 0.1% should be stored at 2-25°C.4
The fixed-combination ophthalmic suspension containing tobramycin 0.3% and dexamethasone 0.05% should be stored upright at 2-25°C and protected from light.10
Depending on the manufacturer, the fixed-combination ophthalmic suspension containing tobramycin 0.3% and dexamethasone 0.1% should be stored upright at 8-253 or 20-25°C.11
The fixed-combination ophthalmic suspension containing tobramycin and loteprednol etabonate (tobramycin 0.3% and loteprednol etabonate 0.5%) should be stored upright at 15-25°C and protected from freezing.5
Information on the physical and/or chemical compatibility of ophthalmic tobramycin with other ophthalmic preparations is not currently available.
Additional Information
The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer's labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Ophthalmic | Ointment | 0.3% | ||
Solution | 0.3%* | Tobramycin Ophthalmic Solution | ||
Tobrex® | Alcon |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Ophthalmic | Ointment | 0.3% Tobramycin and Dexamethasone 0.1% | Alcon | |
Suspension | 0.3% Tobramycin and Dexamethasone 0.05% | Alcon | ||
0.3% Tobramycin and Dexamethasone 0.1%* | TobraDex® | Alcon | ||
Tobramycin and Dexamethasone Ophthalmic Suspension |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
AHFS® Drug Information. © Copyright, 1959-2025, Selected Revisions November 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, MD 20814.
Only references cited for selected revisions after 1984 are available electronically.
1. Akorn, Inc. Tobramycin ophthalmic solution USP, 0.3% prescribing information. Lake Forest, IL; 2016 Oct.
2. Alcon Laboratories. Tobrex® (tobramycin 0.3%) ophthalmic ointment prescribing information. Fort Worth, TX; 2008 Jul.
3. Alcon Laboratories. Tobradex® (tobramycin 0.3% and dexamethasone 0.1%) ophthalmic suspension prescribing information. Fort Worth, TX; 2015 Oct.
4. Alcon Laboratories. Tobradex® (tobramycin 0,3% and dexamethasone 0.1%) ophthalmic ointment prescribing information. Fort Worth, TX; 2010 Apr.
5. Bausch & Lomb, Inc. Zylet® (loteprednol etabonate 0.5% and tobramycin 0.3%) ophthalmic suspension prescribing information. Bridgewater, NJ; 2016 Aug.
6. Alcon Laboratories, Inc. Tobrex® (tobramycin 0.3%) ophthalmic solution prescribing information. Fort Worth, TX; 2012 Jun.
10. Alcon Laboratories, Inc. Tobradex ST® (tobramycin 0.3% and dexamethasone 0.05%) ophthalmic suspension prescribing information. Fort Worth, TX; 2011 Jul.
11. Bausch & Lomb. Tobramycin 0.3% and dexamethasone 0.1% ophthalmic suspension prescribing information. Fort Worth, TX; 2016 Jun.
12. Akorn, Inc. Tobramycin sulfate injection, USP prescribing information. Lake Forest, IL; 2017 Dec.
135. American Academy of Ophthalmology. Preferred practice pattern (PPP) guidelines: conjunctivitis PPP - 2013. From American Academy of Ophthalmology website. Accessed 20 Dec 2017. [Web]
136. Azari AA, Barney NP. Conjunctivitis: a systematic review of diagnosis and treatment. JAMA . 2013; 310:1721-9. [PubMed 24150468]
137. Sheikh A, Hurwitz B, van Schayck CP et al. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev . 2012; :CD001211. [PubMed 22972049]
138. American Academy of Ophthalmology. Preferred Practice Pattern (PPP) guidelines: bacterial keratitis - 2013. From the American Academy of Ophthalmology website. Accessed 5 Dec 2016. [Web]
141. Barnes SD, Kumar NM, Pavin-Langston D et al. Microbial Conjunctivitis. In: Bennett JE, Dolin R, and Blaser MJ, eds. Mandell, Douglas, and Bennett's principles and practices of infectious diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:1392-1401.