Tobramycin (Ophthalmic)
VA CLASSIFICATION
Primary: OP201
Commonly used brand name(s): AKTob; Tobrex.
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).
Category:
Antibacterial (ophthalmic)—
Indications
Note: Bracketed information in the Indications section refers to uses that are not included in U.S. product labeling.
Accepted
Ocular infections (treatment)—Ophthalmic tobramycin is indicated in the treatment of external ocular infections caused by susceptible organisms. {01} {04} {06} {08}
[Blepharitis, bacterial (treatment)]
[Blepharoconjunctivitis (treatment)]
[Conjunctivitis, bacterial (treatment)]
[Dacryocystitis (treatment)]
[Keratitis, bacterial (treatment)]
[Keratoconjunctivitis (treatment)] or
[Meibomianitis (treatment)]—Ophthalmic tobramycin is used as a primary agent in the treatment of bacterial blepharitis, blepharoconjunctivitis, bacterial conjunctivitis, dacryocystitis, bacterial keratitis, keratoconjunctivitis, and meibomianitis caused by coagulase-negative and coagulase-positive staphylococci, Pseudomonas aeruginosa , indole-positive and indole-negative Proteus species, Escherichia coli , Klebsiella pneumoniae , Haemophilus influenzae , Haemophilus aegyptius , Enterobacter aerogenes , Moraxella lacunata (Morax-Axenfeld bacillus), and Neisseria species, including N. gonorrhoeae . {07}
[Keratitis, exposure (treatment)] or
[Keratitis, neuroparalytic (treatment)]—Ophthalmic tobramycin is used in the treatment of exposure keratitis and neuroparalytic keratitis when a secondary bacterial infection is present. {07}
Note: Not all species or strains of a particular organism may be susceptible to tobramycin.
Unaccepted
Tobramycin is not effective against most strains of group D streptococci.
Pharmacology/Pharmacokinetics
Physicochemical characteristics:
Chemical group—
Aminoglycoside.
Molecular weight—
467.52
Mechanism of action/Effect:
Actively transported across the bacterial cell membrane, tobramycin binds to a specific receptor protein on the 30 S subunit of bacterial ribosomes and interferes with an initiation complex between messenger RNA (mRNA) and the 30 S subunit, thus inhibiting protein synthesis. The mRNA base sequence may be misread, thus producing nonfunctional proteins. {04}
Note: Aminoglycosides are bactericidal, while most other antibiotics that interfere with protein synthesis are bacteriostatic. {04}
Absorption:
May be absorbed in minute quantities following topical application to the eye. {07}
Precautions to Consider
Cross-sensitivity and/or related problems
Patients sensitive to other aminoglycosides may be sensitive to this medication also. {04}
Pregnancy/Reproduction
Fertility—
Adequate and well-controlled studies in humans have not been done.
Studies in three types of animals, given tobramycin at doses of up to 33 times the usual human systemic dose, have not shown that tobramycin causes impaired fertility.
Pregnancy—
Adequate and well-controlled studies in humans have not been done.
Studies in three types of animals, given tobramycin at doses of up to 33 times the usual human systemic dose, have not shown that tobramycin causes adverse effects on the fetus.
FDA Pregnancy Category B. {01} {04}
Breast-feeding
Ophthalmic aminoglycosides may be absorbed, especially if tissue damage is present. However, ophthalmic tobramycin is unlikely to be distributed into breast milk in significant amounts since the ophthalmic dose is small. In addition, aminoglycosides are poorly absorbed from the gastrointestinal tract. Therefore, it is unlikely that the nursing infant would absorb significant amounts of tobramycin or that it would cause serious problems in the nursing infant.
Pediatrics
Studies performed to date have not demonstrated pediatrics-specific problems that would limit the usefulness of ophthalmic tobramycin in children.
Geriatrics
No information is available on the relationship of age to the effects of ophthalmic tobramycin in geriatric patients.
Drug interactions and/or related problems
If topical ophthalmic tobramycin is administered while the patient is on a systemic aminoglycoside antibiotic, the patient's total serum aminoglycoside concentration should be monitored. {10}
Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).
Risk-benefit should be considered when the following medical problem exists
Sensitivity to tobramycin
Side/Adverse Effects
Note: Ophthalmic tobramycin should be discontinued if hypersensitivity reactions occur. {01} {04}
Prolonged use of anti-infective agents including tobramycin may result in the overgrowth of nonsusceptible organisms, including fungi. {10}
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Those indicating need for medical attention
Incidence less frequent
Hypersensitivity{01}{04} (itching, redness, swelling, or other sign of eye or eyelid irritation not present before therapy)
Those indicating need for medical attention only if they continue or are bothersome
Incidence less frequent
Burning or stinging of the eyes
Those not indicating need for medical attention
For ophthalmic ointment dosage form only
Blurred vision
Overdose
For more information on the management of overdose or unintentional ingestion, contact a Poison Control Center (see Poison Control Center Listing ).
Clinical effects of overdose
The following effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)-not necessarily inclusive:
Acute and chronic
Increased watering of the eyes{01}{04}
itching, redness, or swelling of the eyes or eyelids{01}{04}
punctate keratitis{10} (painful irritation of the clear front part of the eye)
Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Tobramycin (Ophthalmic).
In providing consultation, consider emphasizing the following selected information (» = major clinical significance):
Before using this medication
» Conditions affecting use, especially:
Sensitivity to tobramycin or other aminoglycosides
Proper use of this medication
Proper administration technique for ophthalmic solution and ointment
» Compliance with full course of therapy
» Proper dosing
Missed dose: Applying as soon as possible; not applying if almost time for next dose
» Proper storage
Precautions while using this medication
Checking with physician if no improvement of symptoms occurs within a few days
Side/adverse effects
Ophthalmic ointments may cause blurred vision for a few minutes after application
Signs of potential side effects, especially hypersensitivity or punctate keratitis
General Dosing Information
Tobramycin ophthalmic solution is not for injection into the eye. {01} {04}
Although some manufacturers recommend doses of 2 drops of ophthalmic solutions at appropriate intervals, the conjunctival sac usually holds less than 1 drop. {07}
When instilling two different ophthalmic solutions, wait at least 5 minutes between instillations to avoid a “wash-out” effect. {07}
At night the ophthalmic ointment may be used as an adjunct to the ophthalmic solution to provide prolonged contact of the medicine with the infection. {01}
If hypersensitivity develops, therapy with ophthalmic tobramycin should be discontinued. {01} {04}
For treatment of adverse effects
Recommended treatment consists of the following:
• For superinfection—Treatment with ophthalmic tobramycin should be discontinued and appropriate alternative therapy started. {10}
Ophthalmic Dosage Forms
TOBRAMYCIN OPHTHALMIC OINTMENT USP
Usual adult and adolescent dose
Mild to moderate infections
Topical, to the conjunctiva, a thin strip (approximately 1.25 cm) of ointment every eight to twelve hours. {01} {04} {09} {10}
Severe infections
Topical, to the conjunctiva, a thin strip (approximately 1.25 cm) of ointment every three to four hours. Treatment should be continued until improvement occurs; then the frequency of administration should be reduced. {01} {04} {09} {10}
Usual pediatric dose
Mild to moderate infections
See Usual adult and adolescent dose . {01} {04} {09} {10}
Severe infections
See Usual adult and adolescent dose . {01} {04} {09} {10}
Strength(s) usually available
U.S.—
0.3% (Rx) [Tobrex{09}{10} (chlorobutanol 0.5%) (mineral oil) (white petrolatum)]
Canada—
0.3% (Rx) [Tobrex{12} (chlorobutanol 0.5%) (mineral oil) (petrolatum base)]
Packaging and storage:
Store between 8 and 27 °C (46 and 80 °F). {10} Protect from freezing.
Auxiliary labeling:
• For the eye.
• Continue medicine for full time of treatment.
TOBRAMYCIN OPHTHALMIC SOLUTION USP
Usual adult and adolescent dose
Mild to moderate infections
Topical, to the conjunctiva, 1 drop every four hours. {07} {09} {10}
Severe infections
Topical, to the conjunctiva, 1 drop every hour. Treatment should be continued until improvement occurs; then the frequency of administration should be reduced. {07} {09} {10}
Usual pediatric dose
Mild to moderate infections
See Usual adult and adolescent dose . {01} {04} {07} {09} {10}
Severe infections
See Usual adult and adolescent dose . {01} {04} {07} {09} {10}
Strength(s) usually available
U.S.—
0.3% (Rx) [AKTob{11} (boric acid) (sodium sulfate) (sodium chloride) (tyloxapol) (sodium hydroxide) (sulfuric acid{14})] [Tobrex{09}{10} (benzalkonium chloride 0.01%) (boric acid) (sodium sulfate) (sodium chloride) (tyloxapol) (sodium hydroxide) (sulfuric acid)][Generic]{13}
Canada—
0.3% (Rx) [Tobrex{12} (benzalkonium chloride 0.01%) (boric acid) (sodium chloride) (sodium hydroxide) (sulfuric acid) (sodium sulfate) (tyloxapol)]
Packaging and storage:
Store between 8 and 27 °C (46 and 80 °F). {10} Protect from freezing.
Auxiliary labeling:
• For the eye.
• Continue medicine for full time of treatment.
Revised: 03/15/1999
References
- Tobrex package insert (Alcon—US). In: PDR Physicians' desk reference for ophthalmology. 16th ed. Montvale, NJ: Medical Economics Data Production Company; 1988. p. 86.
- Open
- Open
- Tobrex package insert (Alcon—Canada). In: Krogh CME, editor. CPS Compendium of pharmaceuticals and specialties. 23rd ed. Ottawa: Canadian Pharmaceutical Association; 1988. p. 929-30.
- Open
- Panel comments on Gentamicin (Ophthalmic) monograph, 11/27/86.
- Panel comments on Tobramycin (Ophthalmic) monograph, 2/6/89.
- USP DI Review comments, Tobramycin (Ophthalmic) monograph, 3/89-5/89.
- Tobrex ointment and solution (Alcon—US). In: PDR Physicians' desk reference for ophthalmology. 21st ed. Montvale, NJ: Medical Economics Data Production Company; 1993. p. 228.
- Tobrex ointment and solution (Alcon—US). In: PDR Physicians' desk reference for ophthalmology. 26th ed. Montvale, NJ: Medical Economics Company; 1998. p. 220.
- AKTob (Akorn). In: PDR Physicians' desk reference for ophthalmology. 26th ed. Montvale, NJ: Medical Economics Company; 1998. p. 202.
- Tobrex (Alcon). In: Gillis MC, editor. CPS Compendium of pharmaceuticals and specialties. 33rd ed. Ottawa: Canadian Pharmacists Association; 1998. p. 1685-6.
- Tobramycin (Bausch & Lomb). In: PDR Physicians' desk reference for ophthalmology. 26th ed. 1998. Montvale, NJ: Medical Economics Company; 1998. p. 246-7.
- AKTob product package (Akorn—US), Rev 8/95, Rec 9/96.
