Veterinary Medicine - January 2008 - (Page 48)

Systemic antifungals PEER-REVIEWED during long-term therapy as with the other antifungals. In dogs, posaconazole at doses as low as 3 mg/kg/day caused neuronal phospholipidosis in the peripheral nervous system.34 Higher doses also affected the CNS, although no neurologic de ciencies were observed with either dose. In people receiving posaconazole, cardiovascular effects including hypertension and hypotension have also been reported.34 a day had median plasma concentrations of 1.69, 1.89, and 5.48 g/ml at days 9, 60, and 90, respectively.37 Clinical trials in cats infected experimentally with Microsporum canis have indicated 30 to 40 mg/kg orally once daily was effective in clearing the infections.37 Adverse effects Terbina ne is typically well-tolerated, but adverse effects can occur. Nausea and vomiting have been reported in cats treated with terbina ne, but these effects decreased when the drug was administered with food.38 Rare but serious adverse effects such as hepatotoxicosis, neutropenia, and toxic epidermal necrolysis have been reported in people.16 There have been minimal reports of drug-drug interactions with terbina ne, but phenobarbital may increase the metabolism of terbina ne, which would decrease terbina ne ef cacy if the dosage is not increased. TERBINAFINE Terbina ne is not an azole antifungal but is classi ed as an allylamine. It is available as 250-mg tablets. Clinical reports of terbina ne use in dogs and cats are sparse and limited primarily to Malassezia species and dermatophyte infections.37,38 The typical cost of terbina ne to treat a 44-lb dog (30 mg/kg orally once a day) is about $1/day. Potential indications Terbina ne has a broad spectrum of activity against yeast and fungi, including dermatophytes.39 Terbina ne is typically active against Aspergillus species, Blastomyces dermatitidis, Cryptococcus neoformans, Histoplasma capsulatum, Microsporum canis, Malassezia pachydermatis, and Sporothrix schenckii; however, in vivo ef cacy studies are lacking.40 Candida species may be less sensitive to terbina ne, so other antifungals may be a better choice.40 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 pro les, and urinalyses. It is important to note that additional treatment options, such as systemic antimicrobials, topical therapy, and baths, are often bene cial and should be considered as a component of a treatment regimen for fungal dermatitis or otitis. Ketoconazole and terbina ne 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 derma- Pharmacokinetics Minimal pharmacokinetic data are available for terbina ne use in dogs or cats. The oral bioavailability in dogs is approximately 46%.41 In dogs, terbina ne is primarily eliminated by hepatic metabolism with the metabolites eliminated in the urine. In people, terbina ne exhibits high plasma protein binding (> 99%).41 Terbina ne administered in cats at 10 to 20 mg/kg orally once a day resulted in median plasma concentrations of 1.38 µg/ml after nine days, increasing to 2.19 and 4.13 g/ml 60 and 120 days after administration, respectively.37 Cats given terbina ne at 30 to 40 mg/kg once 48 January 2008 VETERINARY MEDICINE

Table of Contents Feed for the Digital Edition of Veterinary Medicine - January 2008

Veterinary Medicine - January 2008 Contents Digital Extra Letters Toxicology Brief Idea Exchange A Challenging Case: Phimosis in a Young Adult Dog The Indications and Technique for Continuous Ambulatory Electrocardiographic Recording in Dogs A Review of Selected Systemic Antifungal Drugs for Use in Dogs and Cats CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - January 2008

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