Professional Information
Gentamicin (Otic)
VA CLASSIFICATION
Primary: OT101
Commonly used brand name(s): Garamycin Otic Solution.
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).
*Not commercially available in the U.S.
Category:
Antibacterial (otic)—
Indications
Accepted
Mastoidectomy cavity infections (treatment)
Otitis media, chronic suppurative (treatment)
Otitis media, subacute purulent (treatment) or
Otitis, external (treatment)—Gentamicin otic preparations are used in the treatment of mastoidectomy cavity infections, chronic suppurative otitis media, subacute purulent otitis media with tympanic membrane perforation, {06} or external otitis. {01} {06}
Note: Not all species or strains of a particular organism may be susceptible to gentamicin.
Pharmacology/Pharmacokinetics
Physicochemical characteristics:
Chemical group—
Aminoglycosides. {02}
Mechanism of action/Effect:
Aminoglycoside; actively transported across the bacterial cell membrane, binds to a specific receptor protein on the 30S subunit of bacterial ribosomes, and interferes with an initiation complex between mRNA (messenger RNA) and the 30S subunit, inhibiting protein synthesis. DNA may be misread, thus producing nonfunctional proteins; polyribosomes are split apart and are unable to synthesize protein {03} {04}.
Note: Aminoglycosides are bactericidal, while most other antibiotics that interfere with protein synthesis are bacteriostatic.
Absorption:
Gentamicin may be absorbed in minute quantities following topical application to the ear, especially if the eardrum is perforated or if tissue damage is present.
Precautions to Consider
Cross-sensitivity and/or related problems
Patients sensitive to one aminoglycoside may be sensitive to other aminoglycosides also.
Pregnancy/Reproduction
Adequate and well-controlled studies in humans have not been done. Some studies were done in pregnant rats given systemic doses of gentamicin at 500 times the maximum recommended ophthalmic adult human dose. Newborn rats showed a decrease in kidney weight, body weight, and median glomerular counts. {02}
FDA Pregnancy Category C. {03}
Breast-feeding
It is not known whether otic gentamicin is distributed into breast milk. However, problems in humans have not been documented.
Pediatrics
Appropriate studies on the relationship of age to the effects of gentamicin have not been performed in children up to 6 years of age. Safety and efficacy have not been established. {01}
Geriatrics
Appropriate studies on the relationship of age to the effects of gentamicin have not been performed in the geriatric population. However, no geriatrics-specific problems have been documented to date.
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 problems exist
Perforated or absent eardrum
Sensitivity to aminoglycosides
Side/Adverse Effects
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
Note: Aminoglycosides have been associated with ototoxicity and nephrotoxicity that may be directly related to the dose and duration of treatment. Tinnitus and vertigo are indications of vestibular damage and impending hearing loss. Renal damage is reversible. Serum concentrations of aminoglycosides should be monitored if possible. {03}
Incidence less frequent
Hypersensitivity{01} (itching, redness, swelling, or other sign of irritation not present before therapy)
Those indicating need for medical attention only if they continue or are bothersome
Incidence less frequent
Burning or stinging in the ear
Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Gentamicin (Otic).
In providing consultation, consider emphasizing the following selected information (» = major clinical significance):
Before using this medication
» Conditions affecting use, especially:
Sensitivity to aminoglycosides
Proper use of this medication
Proper administration technique
» 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 within a few days
Side/adverse effects
Signs of potential side effects, especially hypersensitivity
Otic Dosage Forms
Note: The strengths of the dosage forms available are expressed in terms of gentamicin base (not the sulfate salt).
GENTAMICIN SULFATE OTIC SOLUTION
Usual adult and adolescent dose
Topical, to the ear canal, 3 or 4 drops three times a day. {01}
Usual pediatric dose
Safety and efficacy have not been established in children up to 6 years of age.
Strength(s) usually available
U.S.—
Not commercially available. Gentamicin sulfate ophthalmic solution is not indicated for otic use. {02}
Canada—
0.3% (base) (Rx) [Garamycin Otic Solution{01} (benzalkonium chloride) (sodium chloride) (sodium phosphate dibasic and monobasic)]
Packaging and storage:
Store between 2 and 30 °C (36 and 86 °F), unless otherwise specified by manufacturer. Store in a tight container. Protect from freezing.
Auxiliary labeling:
• For the ear.
• Continue medication for full time of treatment.
Note: Dispense in original unopened container.
Revised: 06/09/1999
References
- Gillis MC, editor. CPS Compendium of pharmaceuticals and specialties. 34th ed. Ottawa: Canadian Pharmacists Association; 1999. p. 715-6.
- Garamycin ophthalmic package insert (Schering—US), Rev 9/97, Rec 3/99.
- Lacy CF, Armstrong LL, Ingrim NB, et al. editors. APhA Drug information handbook. 6th ed. Cleveland: Lexi-Corp Inc; 1998. p. 573-7.
- AMA Drug evaluations annual. Chicago: American Medical Association; 1995. p. 1537.
- Panel ballot, sent 5/19/92, due 6/9/92, processed 6/11/92.
| Link to this page |  |
Printable Version |  |
Email Page |
