Ketoconazole

Azole antifungal for systemic mycoses, dermatophytosis, and Malassezia in dogs; hyperadrenocorticism in dogs (inhibits cortisol); topical preparations. Imidazole antifungal with anti-steroidogenic properties (ketoconazole). Mechanism: inhibits fungal CYP51 (ergosterol synthesis) at therapeutic doses; inhibits mammalian CYP enzymes (11β-hydroxylase, 17α-hydroxylase) at higher doses → reduces cortisol synthesis (used for PDH in dogs). Active against Candida, Malassezia, dermatophytes. Hepatically metabolized; numerous drug interactions. Key information Hepatotoxic — monitor liver enzymes. Significant drug interactions (potent CYP3A4 inhibitor). Administer with food (acid-dependent absorption). Not for use in pregnant animals. Inhibits steroidogenesis — used for PDH/Cushing's at high doses.

Oral tablets: Administer orally. May be given with food to improve compliance and reduce GI upset. Administer with food to reduce GI adverse effects. (food enhances absorption and reduces GI effects). Tablets may be crushed. Topical (shampoo): wet coat; apply and lather; 10-min contact time; rinse thoroughly. Store at room temperature; protect from light. If a dose is missed Administer as soon as you remember. If it is almost time for the next scheduled dose, skip the missed dose and resume the normal schedule. Never double up doses to make up for a missed one. Administer with food. Complete the full antifungal course.

GI: nausea, vomiting, anorexia (common — give with food). Hepatotoxicity (elevated liver enzymes — potentially severe; monitor monthly). Adrenal suppression (desired in PDH treatment but can cause hypoadrenocorticism). Teratogenic. Endocrine: reduces cortisol and testosterone synthesis. Numerous CYP3A4 drug interactions (fluconazole, cyclosporine levels increase).

For animals Monitor liver enzymes with prolonged use. — monitor liver enzymes monthly; can be severe. Used for PDH in dogs: monitor cortisol levels (LDDS test) every 4–6 weeks. Numerous CYP3A4 drug interactions. Avoid in pregnant animals. Drug interaction: rifampin, isoniazid, antacids markedly reduce ketoconazole levels. For people handling this medication Wash hands thoroughly with soap and water after handling. Avoid contact with eyes; if contact occurs, flush with water for 15 minutes and seek medical attention. Keep out of reach of children. If accidental ingestion occurs, contact Poison Control (1-800-222-1222). Imidazole antifungal — Wash hands thoroughly with soap and water after handling. after handling. Keep out of reach of children. Pregnant women and women of childbearing age should avoid contact. Teratogenic. Anti-androgenic at high doses.

Contact your veterinarian immediately. Ketoconazole overdose causes liver toxicity, GI signs, and adrenal suppression. Liver enzyme monitoring required. Contact your veterinarian, a veterinary emergency clinic, or the ASPCA Animal Poison Control Center (888-426-4435) immediately. Do not induce vomiting unless specifically directed by a veterinary professional.