VetSheet

ケトコナゾール

Ketoconazole

Ketoconazolum

アゾール系抗真菌薬POTopical犬猫小型哺乳類鳥爬虫類馬

別名: Nizoral · Fungiconazole · ketoconazolum · R-41400

VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス

5-10 mg/kg PO twice dailyPO· q12h· Minimum of 3-6 months
— 🐕

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

動物種別用量

🌎 NA — North America🌍 EU — Europe

犬

適応用量経路頻度期間地域
Coccidioidomycosis (systemic form)5-10 mg/kg PO twice dailyPOq12hMinimum of 3-6 months🌎 NA
Coccidioidomycosis (CNS form)15-20 mg/kg PO twice dailyPOq12hMinimum of 3-6 months🌎 NA
Coccidioidomycosis (bony lesions or relapses)5 mg/kg PO every other dayPOq48hLifelong🌎 NA
Coccidioidomycosis10-30 mg/kg PO divided twice a dayPOq12h6-12 months🌎 NA
Blastomycosis10 mg/kg PO twice daily (15-20 mg/kg PO twice daily if CNS involvement)POq12hAt least 3 months🌎 NA
Blastomycosis20 mg/kg/day PO once daily or divided twice daily; 40 mg/kg divided twice daily for ocular or CNS involvementPOq24h or q12hAt least 2-3 months or until remission🌎 NA
Histoplasmosis10 mg/kg PO once a day or twice a dayPOq24h or q12hAt least 3 months🌎 NA
Histoplasmosis10-20 mg/day PO once daily or divided twice dailyPOq24h or q12hAt least 2-3 months or until remission🌎 NA
Aspergillosis20 mg/kg POPONot specifiedAt least 6 weeks🌎 NA
Nasal aspergillosis10 mg/kg PO once daily (q24h) or 5 mg/kg PO q12hPOq24h or q12hMany weeks; continue 1 month beyond last detection🌎 NA
Cryptococcosis10 mg/kg PO once daily or divided twice dailyPOq24h or q12hMaintenance🌎 NA
Fungal myocarditis10 mg/kg PO three times dailyPOq8h—🌎 NA
Candidiasis10 mg/kg PO once daily (q24h) or 5 mg/kg PO q12hPOq24h or q12hMany weeks; continue 1 month beyond last detection🌎 NA
Sporotrichosis15 mg/kg PO q12hPOq12hMany weeks; continue 1 month beyond last detection🌎 NA
Malassezia dermatitis (severe)5 mg/kg PO once daily to 10 mg/kg twice dailyPOq24h to q12hUntil clinical signs abate and no organisms seen🌎 NA
Malassezia dermatitis5-10 mg/kg PO twice a dayPOq12h30 days🌎 NA
Malassezia dermatitis5-10 mg/kg PO daily for 10 days, then every other day for an additional 10 daysPOq24h then q48h20 days🌎 NA
Malassezia dermatitis5 mg/kg twice daily for 21-30 days, may increase to 10 mg/kg PO twice daily if poor responsePOq12h21-30 days🌎 NA
Malassezia dermatitis2.5-10 mg/kg PO once daily (q24h) for 7-14 days; once a good response is seen taper to every other day (q48h)POq24h then q48hUntil complete remission🌎 NA
Hyperadrenocorticism5-10 mg/kg PO twice daily initially; may increase to 15 mg/kg PO twice dailyPOq12hLong-term🌎 NA
Hyperadrenocorticism5 mg/kg q12h for 5-7 days, increase to 10 mg/kg q12h for 10-14 days; many require 15-20 mg/kg q12hPOq12hLong-term🌎 NA
Hyperadrenocorticism (palliative)15 mg/kg PO q12hPOq12hLong-term🌎 NA
Reduce cyclosporine dosage5-10 mg/kg PO per dayPOq24hConcurrent with cyclosporine🌎 NA
Perianal fistula (with cyclosporine)7.5 mg/kg PO twice dailyPOq12h—🌎 NA
Atopic dermatitis (with cyclosporine)5 mg/kg/dayPOq24h—🌎 NA
IMHA (with cyclosporine)10 mg/kg/dayPOq24h—🌎 NA
  • Blastomycosis: Used with amphotericin B
  • Blastomycosis: Used with amphotericin B
  • Histoplasmosis: Treat at least 30 days after complete resolution. Maintenance 5 mg/kg PO every other day indefinitely if relapse.
  • Histoplasmosis: Used with amphotericin B
  • Aspergillosis: May require long-term/maintenance therapy
  • Nasal aspergillosis: Itraconazole somewhat more effective
  • Cryptococcosis: Used with amphotericin B
  • Malassezia dermatitis: Often used with therapeutic shampoos
  • Hyperadrenocorticism: Monitor with ACTH stimulation test
  • Perianal fistula (with cyclosporine): Given with cyclosporine 0.5-0.75 mg PO twice daily
  • Atopic dermatitis (with cyclosporine): Given with cyclosporine 2.5 mg/kg/day
  • IMHA (with cyclosporine): Allows reduction of cyclosporine dose

猫

適応用量経路頻度期間地域
Coccidioidomycosis10-30 mg/kg PO divided twice a dayPOq12h6-12 months🌎 NA
Coccidioidomycosis50 mg per cat PO once daily; or 25-75 mg per cat q12-48hPOq24h or q12-48h9-12 months on average🌎 NA
Blastomycosis10 mg/kg q12h POPOq12hAt least 60 days🌎 NA
Cryptococcosis10 mg/kg twice dailyPOq12h—🌎 NA
Aspergillosis10 mg/kg PO q12hPOq12h—🌎 NA
Dermatophytosis10 mg/kg PO once daily with an acidic mealPOq24hProlonged; 2 weeks beyond clinical cure and negative cultures🌎 NA
Sporotrichosis5-10 mg/kg PO q12-24hPOq12-24h2-4 months on average🌎 NA
  • Coccidioidomycosis: Use in cats is controversial
  • Blastomycosis: Used with amphotericin B
  • Cryptococcosis: Can produce anorexia and debility at this dosage
  • Dermatophytosis: Reserved for when griseofulvin ineffective or not tolerated

小型哺乳類

適応用量経路頻度期間地域
Susceptible infections (Rabbits)10-40 mg/kg per day POPOq24h14 days🌎 NA
Systemic mycoses/candidiasis (Hamsters, Gerbils, Mice, Rats, Guinea pigs, Chinchillas)10-40 mg/kg per day POPOq24h14 days🌎 NA

鳥

適応用量経路頻度期間地域
Severe refractory candidiasis in Psittacines5-10 mg/kg as a gavage twice dailyPO (gavage)q12h14 days🌎 NA
Susceptible fungal infections (most species)200 mg/LPO (water)Continuous7-14 days🌎 NA
Susceptible fungal infections (most species)10-20 mg/kgPO (feed)Daily7-14 days🌎 NA
Susceptible fungal infections (Moluccan Cockatoos)20-30 mg/kg PO twice dailyPOq12h—🌎 NA
Susceptible fungal infections (Ratites)5-10 mg/kg PO once dailyPOq24h—🌎 NA
  • Severe refractory candidiasis in Psittacines: Dissolve in 0.2 mL 1 N HCl and add 0.8 mL water
  • Susceptible fungal infections (most species): Dissolve in acid prior to adding to water
  • Susceptible fungal infections (most species): Add to favorite food or mash

爬虫類

適応用量経路頻度期間地域
Susceptible infections (most species)15-30 mg/kg PO once dailyPOq24h2-4 weeks🌎 NA
Fungal shell diseases in turtles/tortoises25 mg/kg PO once a dayPOq24h2-4 weeks🌎 NA

馬

適応用量経路頻度期間地域
Susceptible yeasts and Aspergillus spp5 mg/kg PO once dailyPOq24h—🌎 NA
Scopulariopsis pneumonia30 mg/kg q12hNG tubeq12h—🌎 NA
  • Susceptible yeasts and Aspergillus spp: Using commercial oral solution
  • Scopulariopsis pneumonia: Administered via NG tube mixed with 0.2 Normal hydrochloric acid

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

診察中ですか？VetSheet の AI が薬剤・用量・投与期間を構造化された診察記録に直接記入します。VetSheet の仕組みを見る

概要

ケトコナゾールは第一世代の​イミダゾール系抗真菌薬​です。安全性と有効性の観点から、現在ではより新しいトリアゾール系（イトラコナゾールやフルコナゾールなど）に取って代わられつつありますが、特定の全身性真菌感染症（ブラストミセス症、ヒストプラズマ症、コクシジオイデス症、マラセチア皮膚炎など）の治療においては、依然として費用対効果の高い選択肢です。

​臨床のポイント：​ 抗真菌作用に加えて、ケトコナゾールは哺乳類のシトクロムP450酵素の強力な阻害剤でもあります。このユニークな特性は、獣医療において以下の2つの主な目的で適応外使用（オフラベル使用）されます：

  • ​薬剤節約：​ 肝代謝を阻害することで、​シクロスポリン​のような高価な薬剤の必要用量（およびコスト）を削減するため。
  • ​内分泌治療：​ 副腎のステロイド産生を可逆的に阻害することにより、​犬の副腎皮質機能亢進症（クッシング症候群）​の内科的治療の選択肢として。

​注意：​ 猫では胃腸毒性および肝毒性のリスクが高いため、ケトコナゾールの使用には大きな議論があり、多くの獣医師は猫の患者にはイトラコナゾールを好んで使用します。

作用機序

​Antifungal Action:​ Ketoconazole inhibits lanosterol 14α-demethylase, a fungal cytochrome P450 enzyme → blocks the conversion of lanosterol to ergosterol → depletion of ergosterol in the fungal cell membrane → accumulation of toxic intermediate sterols → increased cellular membrane permeability and cell death. It is primarily fungistatic but can be fungicidal at high concentrations or prolonged exposures.

​Endocrine/Metabolic Action:​ It reversibly inhibits mammalian cytochrome P450 enzymes (specifically CYP11A1 and CYP17) → blocks the synthesis of adrenal and gonadal steroids → decreases cortisol and testosterone production.

​Immunomodulatory Action:​ Inhibits 5-lipooxygenase, providing mild anti-inflammatory effects, and suppresses T-lymphocyte proliferation.

安全性・警告

禁忌

  • Known hypersensitivity to ketoconazole
  • Controversial/Contraindicated in cats (due to toxicity risks)
  • Concurrent use with cisapride or ivermectin (in dogs)
  • Hepatic insufficiency
  • Pregnancy (due to possible teratogenic effects)

有害事象

  • Anorexia (most common, especially in cats)
  • Vomiting
  • Diarrhea
  • Hepatic toxicity (cholangiohepatitis, increased liver enzymes)
  • Thrombocytopenia (rare)
  • Reversible lightening of haircoat
  • Transient suppression of gonadal and adrenal steroid synthesis
  • Infertility in male dogs (reversible)
  • Hepatotoxicity
  • Alterations in hair-coat colour
  • Thrombocytopenia (at high doses)
  • Adrenal insufficiency (at high doses)
  • Cataract development (in dogs)
  • Teratogenic effects

注意事項

Use with caution in patients with hepatic disease or thrombocytopenia. Ketoconazole is a known teratogen and embryotoxin; weigh risks vs. benefits in pregnant animals. It may cause reversible infertility in male dogs by decreasing testosterone synthesis. Dogs undergoing high-dose antifungal therapy may need additional glucocorticoid support during periods of acute stress due to adrenal suppression.

医薬品相互作用

Alcohol

May produce a disulfiram-like reaction (vomiting)

AntacidsModerate

May reduce oral absorption of ketoconazole; administer at least 1 hour before or 2 hours after

Tricyclic Antidepressants (amitriptyline, clomipramine)

Ketoconazole may reduce metabolism and increase adverse effects

Benzodiazepines (midazolam, triazolam)

Ketoconazole may increase levels

Buspirone

Plasma concentrations may be elevated

Busulfan

Ketoconazole may increase levels

Calcium-channel blockers (amlodipine, verapamil)

Ketoconazole may increase levels

Cisapride

Ketoconazole may increase cisapride levels and possibility for toxicity; use together contraindicated

Corticosteroids

Ketoconazole may inhibit metabolism; potential for increased adverse effects

Cyclophosphamide

Ketoconazole may inhibit metabolism; potential for increased toxicity

Cyclosporine

Increased cyclosporine levels (often used therapeutically to reduce cyclosporine dose)

Digoxin

Ketoconazole may increase digoxin levels

Fentanyl/Alfentanil

Ketoconazole may increase fentanyl or alfentanil levels

H2-blockers (ranitidine, famotidine)

Increased gastric pH may reduce ketoconazole absorption

Hepatotoxic drugs

Should be used cautiously together due to additive hepatotoxicity risk

Isoniazid

May affect ketoconazole levels; concomitant use not recommended

Ivermectin

Ketoconazole may increase risk for neurotoxicity; should never be used together in dogs

Macrolide antibiotics (erythromycin, clarithromycin)

May increase ketoconazole concentrations

Mitotane

Not recommended together; adrenolytic effects of mitotane may be inhibited by ketoconazole

Phenytoin

May decrease ketoconazole levels

Proton-pump inhibitors (omeprazole)

Increased gastric pH may reduce ketoconazole absorption

Quinidine

Ketoconazole may increase quinidine levels

Rifampin

May decrease ketoconazole levels; ketoconazole may increase rifampin levels

Sucralfate

May reduce absorption of ketoconazole

Sulfonylurea antidiabetic agents (glipizide, glyburide)

Ketoconazole may increase levels; hypoglycemia possible

Theophylline

Ketoconazole may decrease serum theophylline concentrations; monitor levels

Vincristine/Vinblastine

Ketoconazole may inhibit vinca alkaloid metabolism and increase levels

Warfarin

Ketoconazole may cause increased prothrombin times

CiclosporinMajor

Ketoconazole increases blood levels of ciclosporin (used therapeutically to reduce ciclosporin dose requirements)

Amphotericin BModerate

Used synergistically in systemic fungal disease, allowing for a reduced dose of amphotericin B

Proton-pump inhibitors (PPIs)Moderate

Increases gastric pH, which impairs the absorption of ketoconazole; stagger dosing

H2 blockersModerate

Increases gastric pH, which impairs the absorption of ketoconazole; stagger dosing

AntimuscarinicsModerate

Increases gastric pH, which impairs the absorption of ketoconazole; stagger dosing

MethylprednisoloneModerate

Ketoconazole extends the activity of methylprednisolone

AntihistaminesModerate

Inhibits the metabolism of antihistamines (extrapolated from human data)

Oral hypoglycaemicsMajor

Inhibits the metabolism of oral hypoglycaemics (extrapolated from human data)

AntiepilepticsMajor

Inhibits the metabolism of antiepileptics (extrapolated from human data)

監視

  • Liver enzymes with chronic therapy (at least every 1-2 months)
  • CBC with platelets
  • Clinical efficacy
  • Adverse effects (GI signs, jaundice)
  • Liver function tests (routine monitoring recommended)
  • Platelet count (if high doses are used)
  • Adrenal function/clinical signs of hypoadrenocorticism

薬物動態

半減期

犬1-6 hours (avg. 2.7 hours)

吸収

Highly variable oral bioavailability in dogs (4-89%). Absorption is enhanced in an acidic environment and may be increased with food. Poor oral absorption of tablets in horses, but increases to 23% if given with hydrochloric acid, and 60% with oral solution.

分布

Distributed into bile, cerumen, saliva, urine, synovial fluid, and CSF (CSF levels <10% of serum). High levels in liver, adrenals, and pituitary gland. 84-99% bound to plasma proteins. Crosses the placenta and is found in milk.

代謝

Extensively metabolized by the liver into several inactive metabolites.

消失

Metabolites are excreted primarily into the feces via the bile. About 13% is excreted into the urine (only 2-4% unchanged).

過剰投与

No reports of acute toxicity associated with overdosage were located. The oral LD50 in dogs is >500 mg/kg. In the event of an acute overdose, employ supportive measures, including gastric lavage with sodium bicarbonate.

製品

製剤

  • Oral tablets
  • Oral suspension (compounded)
  • Topical preparations
  • 200 mg oral tablet

動物用医薬品

  • None for systemic use
  • Fungiconazole 200 mg tablet

ヒト用医薬品

  • Ketoconazole Tablets: 200 mg (scored)

規制ステータス

European Union✓ 承認済み処方箋医薬品EMA
🐕 Dogs🐈 Cats

POM-V classification

United Kingdom✓ 承認済み処方箋医薬品VMD
🐕 Dogs🐈 Cats

POM-V (Prescription Only Medicine - Veterinarian)

規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

保管・安定性

Store tablets at room temperature in well-closed containers. Compounded oral suspensions (20 mg/mL) retain >95% potency for 60 days when stored at 5°C or 25°C and protected from light.

飼主向け情報

  • ​投与方法：​ 吸収を高め、胃の不快感を軽減するために、この薬は食事と一緒に与えてください。ペットが嘔吐したり食欲をなくしたりした場合は、1日の投与量を分けて与えることで改善する場合があります。
  • ​副作用：​ 食欲不振、嘔吐、下痢に注意してください。これらの症状が現れた場合は、獣医師に連絡してください。猫ではこれらの副作用がより一般的に見られます。
  • ​被毛の変化：​ 治療中、ペットの毛色が明るくなる（退色する）ことがありますが、これは治療を終えれば元に戻ります。
  • ​治療への専念：​ 真菌感染症は通常、数ヶ月にわたる継続的な治療を必要とします。ペットの症状が良くなったように見えても、感染が容易に再発する可能性があるため、自己判断で投薬を中止しないでください。
  • ​警告：​ ケトコナゾールは多くの薬と相互作用するため、ペットが服用している​すべて​の薬を獣医師に伝えてください。

VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。