A review of selected systemic antifungal drugs for use in dogs and cats - Veterinary Medicine
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A review of selected systemic antifungal drugs for use in dogs and cats
This pharmacologist reviews a few of your antifungal choices, specifically the azoles andterbinafine. These drugs have a broad spectrum of activity—with some important differences.


VETERINARY MEDICINE


There have been minimal reports of drug-drug interactions with terbinafine, but phenobarbital may increase the metabolism of terbinafine, which would decrease terbinafine efficacy if the dosage is not increased.

CONCLUSION

Many different antifungal agents for dogs and cats are at your disposal. Adverse effects commonly observed with systemic antifungals include nausea, vomiting, anorexia, and diarrhea. Severe adverse effects such as hepatotoxicosis and blood dyscrasias can also occur but are less frequent. Routine monitoring of patients receiving antifungals should minimally include complete blood counts, serum chemistry profiles, and urinalyses. It is important to note that additional treatment options, such as systemic antimicrobials, topical therapy, and baths, are often beneficial and should be considered as a component of a treatment regimen for fungal dermatitis or otitis.

Ketoconazole and terbinafine are cost-effective treatment options for dermatophyte infections or yeast dermatitis and otitis in dogs and cats.

Itraconazole is also expected to be an effective treatment for dermatophyte infections and yeast dermatitis, but it may be cost-prohibitive in some cases.

Fluconazole exhibits poor activity against Malassezia species and dermatophytes, so is not routinely recommended for those indications.

Voriconazole and posaconazole are the newest azoles available in the United States with a primary indication of treating resistant fungal infections. However, their routine use is not recommended because of the limited information available for dogs and cats, their high cost, and the potential for inducing resistance. ?

ACKNOWLEDGMENT

I would like to thank Dr. Stuart Snyder for his help with this review.

Butch KuKanich, DVM, PhD, DACVCP
Department of Anatomy and Physiology
College of Veterinary Medicine
Kansas State University
Manhattan, KS 66506

REFERENCES

1. Papich MG, Heit MC, Riviere JE. Antifungal and antiviral drugs. In: Adams HR, ed. Veterinary pharmacology and therapeutics. 8th ed. Ames: Iowa State University Press, 2001;918-946.

2. Hof H. A new, broad-spectrum azole antifungal: posaconazole—mechanisms of action and resistance, spectrum of activity. Mycoses 2006;49(suppl 1):2-6.

3. Consigli J, Danielo C, Gallerano V, et al. Cutaneous leishmaniasis: successful treatment with itraconazole. Int J Dermatol 2006;45(1):46-49.

4. Pagniez F, Abdala-Valencia H, Marchand P, et al. Antileishmanial activities and mechanisms of action of indole-based azoles. J Enzyme Inhib Med Chem 2006;21(3):277-283.

5. Toubiana J, Armengaud JB, Dupouy Camet J, et al. Oral fluconazole treatment for extensive cutaneous leishmaniasis in an 11-year-old child. Pediatr Infect Dis J 2006;25(11):1083-1084.

6. Rosales MS, Marsella R, Kunkle G, et al. Comparison of the clinical efficacy of oral terbinafine and ketoconazole combined with cephalexin in the treatment of Malassezia dermatitis in dogs—a pilot study. Vet Dermatol 2005;16(3):171-176.

7. Baxter JG, Brass C, Schentag JJ, et al. Pharmacokinetics of ketoconazole administered intravenously to dogs and orally as tablet and solution to humans and dogs. J Pharm Sci 1986;75(5):443-447.

8. Lelawongs P, Barone JA, Colaizzi JL, et al. Effect of food and gastric acidity on absorption of orally administered ketoconazole. Clin Pharm 1988;7(3):228-235.

9. Kuroha M, Azumano A, Kuze Y, et al. Effect of multiple dosing of ketoconazole on pharmacokinetics of midazolam, a cytochrome P-450 3A substrate in beagle dogs. Drug Metab Dispos 2002;30(1):63-68.


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