Otomax Ointment (Canada)

This page contains information on Otomax Ointment for veterinary use.
The information provided typically includes the following:
  • Otomax Ointment Indications
  • Warnings and cautions for Otomax Ointment
  • Direction and dosage information for Otomax Ointment

Otomax Ointment

This treatment applies to the following species:


Manufacturer: Merck Animal Health

Antibiotic, Anti-inflammatory, Antifungal

Gentamicin 3 mg/g Betamethasone 1 mg/g Clotrimazole 10 mg/g

For Otic Use in Dogs Only


DIN 00817112


Gentamicin as sulfate is a water soluble (bactericidal) antibiotic of the aminoglycoside group, derived from Micromonospora, an actinomycete.

Betamethasone valerate is a synthetic glucocorticoid derivative of prednisolone.

Clotrimazole is a synthetic antifungal belonging to the imidazole family.

Each gram of OTOMAX Ointment contains 3 mg gentamicin as gentamicin sulfate USP, 1 mg of betamethasone as betamethasone valerate USP, and 10 mg clotrimazole USP in a mineral oil based vehicle.


Gentamicin: Gentamicin sulfate, a broad spectrum aminoglycoside antibiotic, is a highly effective treatment for bacterial infections of the ear and skin. In vitro tests have determined that gentamicin is bactericidal and acts by inhibiting normal protein synthesis in susceptible microorganisms. Specifically, gentamicin is active against the following organisms commonly isolated from canine ears and skin: Staphylococcus aureus, other Staphylococcus spp., Pseudomonas aeruginosa, Proteus spp., Escherichia coli, Alcaligenes spp., and Klebsiella spp.

Betamethasone: Betamethasone valerate is a synthetic adrenocorticoid for dermatologic use. Betamethasone, an analog of prednisolone, has a high degree of corticosteroid activity and a slight degree of mineralocorticosteroid activity. Betamethasone valerate, the 17-valerate ester of betamethasone, has been shown to provide anti-inflammatory and anti-pruritic activity in the topical management of corticosteroid-responsive otitis externa.

Topical corticosteroids can be absorbed from normal, intact skin. Inflammation can increase percutaneous absorption. Once absorbed through the skin, topical corticosteroids are handled through pharmacokinetic pathways similar to systemically administered corticosteroids.

Clotrimazole: Clotrimazole is a broad-spectrum antifungal agent that is used for the treatment of dermal infections caused by various species of pathogenic dermatophytes and yeasts. The primary action of clotrimazole is against dividing and growing organisms.

In vitro, clotrimazole exhibits fungistatic and fungicidal activity against isolates of Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum, Microsporum canis, Candida spp., and Malassezia pachydermatis (Pityrosporum canis). Resistance to clotrimazole is very rare among the fungi that cause superficial mycoses.

In an induced otitis externa infected with Malassezia pachydermatis, 1% clotrimazole in the OTOMAX vehicle was effective both microbiologically and clinically in terms of reduction of exudate odor and swelling.

In studies of the mechanism of action, the minimum fungicidal concentration of clotrimazole caused leakage of intracellular phosphorus compounds into the ambient medium with concomitant breakdown of cellular nucleic acids and accelerated potassium efflux. These events began rapidly and extensively after addition of the drug.

Clotrimazole is very poorly absorbed following dermal application.

Gentamicin-Betamethasone-Clotrimazole: By virtue of its three active ingredients, OTOMAX has antibacterial, anti-inflammatory, and antifungal activity.

In component efficacy studies, the compatibility and additive effect of each of the components were demonstrated.

In clinical field trials, OTOMAX was effective in the treatment of otitis externa associated with bacteria and Malassezia pachydermatis.

OTOMAX reduced discomfort, redness, swelling, exudate, and odor, and exerted a strong antimicrobial effect.

Otomax Ointment Indications

OTOMAX is indicated for the treatment of canine acute and chronic otitis externa associated with yeast (Malassezia pachydermatis, formerly Pityrosporum canis) and/or bacteria susceptible to gentamicin.

Dosage and Administration

The external ear and ear canal should be properly cleaned and dried before treatment. Remove foreign material, debris, crusted exudates, etc., with suitable non-irritating solutions. Excessive hair should be removed from the treatment area of the external ear. Instill OTOMAX Ointment into the cleaned external ear canal twice daily for 7 days.

- Dogs weighing less than 15 kg: 4 drops per affected ear.

- Dogs weighing 15 kg or more: 8 drops per affected ear.

Massage the external ear carefully after medication is instilled to assure proper distribution.


If hypersensitivity to any of the components occurs, treatment should be discontinued and appropriate alternate therapy instituted. Concomitant use of drugs known to induce ototoxicity should be avoided. Do not use in dogs with known perforation of eardrums.

Otomax Ointment Caution

The use of OTOMAX Ointment has been associated with deafness or partial hearing loss in a small number of dogs. The hearing deficit is usually temporary. If hearing or vestibular dysfunction is noted during the course of treatment, discontinue use of OTOMAX Ointment immediately and flush the ear canal thoroughly with a non-toxic solution.

Antibiotic susceptibility of the pathogenic organism(s) should be determined prior to use of this preparation. Use of topical antibiotic and antifungals may permit overgrowth of non-susceptible bacterial, fungi or yeast. If this occurs, treatment should be instituted with other appropriate agents as indicated. Experimentally, it has been demonstrated that corticosteroids, especially at high levels, may result in delayed wound healing.

Adverse systemic reactions have been observed following the oral ingestion of some topical corticosteroid preparations. Patients should be closely observed for the usual signs of adrenocorticoid overdosage which include sodium retention, potassium loss, fluid retention, weight gain, polydipsia and/or polyuria. Prolonged use or overdosage may produce adverse immunosuppressive effects.

TOXICOLOGY: Clinical and safety studies with OTOMAX have shown a wide safety margin at the recommended dose level in dogs (see CAUTION).

Side Effects

Gentamicin sulfate is an aminoglycoside antibiotic. While aminoglycosides are absorbed poorly from skin, intoxication may occur when aminoglycosides are applied topically for prolonged periods of time to large wounds, burns, or any denuded skin, particularly if there is renal insufficiency. All aminoglycosides have the potential to produce reversible and irreversible vestibular, cochlear, and renal toxicity.


Keep out of the reach of children.

Wash hands carefully after applying the product. In case of accidental contact with the eyes, rinse with copious amounts of water.

Do not handle the product if you have known hypersensitivity against compounds in the product.

STORAGE CONDITIONS: Store between 2° and 30° C. Shake well before use when using the 12.5 g bottle, 30 g bottle, and 215 g bottle.

How Supplied

OTOMAX Ointment is available in 12.5 g (code 600125), 30 g (code 600030) and 215 g (code 600215) plastic bottles, and 7.5 g (code 600075) and 15 g (code 600015) tubes.

® Registered trademark of Intervet Canada Corp.

Intervet Canada Corp., 16750, route Transcanadienne, Kirkland QC, H9H 4M7

For technical enquiries, call toll free 1 888 306-0069.


NAC No.: 12080724

Intervet Canada Corp.

Order Desk:   514-428-7013
Toll-Free:   866-683-7838
Fax:   Toll-free 888-498-4444; local 514-428-7014
Website:   www.merck-animal-health.ca
Every effort has been made to ensure the accuracy of the Otomax Ointment information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the Canadian product label or package insert.

Copyright © 2014 North American Compendiums. Updated: 2014-04-11