Treatment of Fungal Infections

Table 3-6 - Systemic Antimycotic Agents

Formulation

Comments

Indications

Side Effects

Dog dose (D)
Cat dose (C)

Griseofulvin

125 mg and 500 mg tablets

Administered with fatty meal

Dermatophytosis

Teratogenic! Vomiting, diarrhea, idiosyncratic bone marrow suppression

Microsize crystal form: 25-60 mg/kg q 12 h, ultramicrosize Gris-PEG 2.5-10 mg/kg q 12 h (D,C)

Ketoconazole

200 mg tablet

Administer with food! Increases blood levels of cyclosporin, phenytoin, and some antihistamines. Rifampin may decrease ketoconazole serum levels. With high-dose therapy, a slow increase over several days may minimize adverse effects.

Malassezia-related infections, dermatophytosis, blastomycosis, cryptococcosis, coccidioidomycosis, sporotrichosis, nocardiosis, hyperadrenocorticism

Anorexia, nausea (quite common), vomiting, diarrhea, cholangiohepatitis

2.5-10 mg/kg q 12 h for Malassezia infection (D, C), 10 mg/kg q 12 h for dermatophytosis (D, C), up to 20 mg/kg q 12 h for systemic mycoses (D, C), and hyperadrenocorticism (D)

Itraconazole

100 mg capsule

Administer with food! If given concurrently with cyclosporin, some antihistamines, phenytoin, or oral antidiabetic agents, the drug doses may have to be decreased. Rifampin may decrease itraconazole serum levels.

Malassezia and Candida infections, dermatophytoses, systemic mycoses

Anorexia, nausea, hepatotoxicity

5-10 mg/kg q 12-24h (D,C)

Potassium iodide

Give with food

Sporotrichosis

Vomiting, diarrhea, depression, anorexia, hypothermia, cardiovascular failure in cats; ocular and nasal discharge, scaling and dry coat in dogs.

40 mg/kg q 12 h (D); 20 mg/kg q 12-24 h (C)

Terbinafine

250 mg tablet

Fairly new and costly drug at time of writing, limited promising information available.

Dermatophytosis

Vomiting

10-30 mg/kg q 24 h for 2-4 weeks (D,C)

Fluconazole

50-mg, 100-mg, 150-mg, 200-mg capsules

Penetrates into central nervous system (CNS) and saliva well. Dose needs to be decreased in patients with renal insufficiency. Rifampin may decrease fluconazole serum levels. Increases blood levels of cyclosporine, phenytoin and some antihistamines.

Blastomycosis, histoplasmosis, cryptococcosis, oral candidiasis

Vomiting, diarrhea, nausea, hepatotoxicity

2.5-5 mg/kg q 12 h (D); 2.5-10 mg/kg q 12 h (C)

Amphotericin B*

50-mg dry substance/bottle

Relatively toxic, thus treatment is dangerous and referral may be considered. Incompatible with saline and lactated Ringer's solution and other drugs

In combination with ketoconazole for blastomycosis, histoplasmosis, coccidiomycosis and sporotrichosis, in combination with flucytosine for cryptococcosis and candidiasis

Nephrotoxicity, anemia, phlebitis, hypokalemia

0.5 mg/kg IV in 5% dextrose every other day (D), 0.15 mg/kg IV in 5% dextrose every other day (C). Safer is subcutaneous administration of 0.5 mg/kg, amphotericin is in 400 ml of 0.45% saline containing 2.5% dextrose q 3-4 d's to a total cumulative dose of 10-25 mg/kg.