VetSheet

エストラジオールシピオネート

Estradiol Cypionate

Estradiol cyclopentanepropionate

ホルモン剤（エストロゲン）IMPOImplants犬猫馬牛

別名: Delestrogen · DepoEstradiol · Depogen · Dura-Estrin · ECP · E-Cypionate · Estra-D · Estrace · Estro-Cyp · Estroject · depGynogen · Femtrace · Gynodiol · beta-oestradiol · dihydrofolliculin · dihydrotheelin · dihydroxyoestrin · estradiolum · NSC-9895 · NSC-20293 · oestradiol cyclopentylpropionate · oestradiol cypionate

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

44 micrograms/kg (0.044 mg/kg) IM once; during day 4 estrus to day 2 of diestrusIM· once
— 🐕

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
Pregnancy avoidance after mismating44 micrograms/kg (0.044 mg/kg) IM once; during day 4 estrus to day 2 of diestrusIMonce—🌎 NA
  • Pregnancy avoidance after mismating: Rarely used for this indication today as there are safer, more effective treatments. Toxic at >=100 micrograms/kg.

猫

適応用量経路頻度期間地域
Pregnancy avoidance after mismating250 micrograms/kg (0.25 mg/kg) IM once 6 days after coitus; or 0.25 mg/cat IM at 40 hours after coitusIMonce—🌎 NA
  • Pregnancy avoidance after mismating: Rarely used for this indication today as there are safer, more effective treatments.

馬

適応用量経路頻度期間地域
To enhance estrus behavior and receptivity in ovariectomized mares5-10 mg (total dose) IM onceIMonce—🌎 NA
Treatment of mares with estrogen-responsive incontinence4-10 micrograms/kg estradiol cypionate IM daily for three days and then every other dayIMdaily then q48h3 days then ongoing🌎 NA
  • Treatment of mares with estrogen-responsive incontinence: Some mares will improve, but does not 'cure'.

牛

適応用量経路頻度期間地域
AnyIllegal———🌎 NA
  • Any: The FDA has stated that the use of ECP in food-producing animals is illegal.

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。

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概要

エストラジオールシピオネートは、長時間作用型の天然エストロゲンエステル誘導体です。歴史的には小動物の妊娠中絶薬（交尾後の避妊）として広く使用されてきましたが、​致命的な骨髄抑制​（再生不良性貧血）や​子宮蓄膿症​を引き起こすリスクが高いため、現在ではほとんどの獣医繁殖専門医によって推奨されていません。より安全で効果的な代替薬が好まれています。

​臨床上の注意点​：FDAは、この薬物を食用動物に使用することを厳格に禁止しており、対象動物への投与や調剤は違法となります。

作用機序

Estradiol is the most active endogenous estrogen. It diffuses across the cell membrane and binds to specific intracellular ​estrogen receptors (ERα and ERβ)​.

The receptor-hormone complex translocates to the nucleus → binds to ​estrogen response elements (EREs)​ on DNA → modulates gene transcription.

​Key systemic effects include:​

  • ​Reproductive:​ Stimulates normal growth and development of female sex organs, increases cervical mucosal secretions, thickens vaginal mucosa, and induces endometrial proliferation and uterine tone.
  • ​Skeletal:​ Increases calcium deposition, accelerates epiphyseal closure, and promotes bone formation.
  • ​Endocrine:​ Modulates pituitary gonadotropin release, which can inhibit lactation, ovulation, and androgen secretion.

安全性・警告

禁忌

  • Pregnancy (teratogenic and causes fetal bone marrow depression)
  • Food-producing animals (illegal per FDA)
  • Ferrets (highly susceptible to severe bone marrow toxicity)
  • Estrogen-responsive incontinence in small animals (safer alternatives like DES or estriol should be used)

有害事象

  • Bone marrow toxicity (thrombocytopenia, leukopenia, fatal aplastic anemia)
  • Cystic endometrial hyperplasia
  • Pyometra
  • Mammary neoplasia
  • Feminization (in males)
  • Prolonged estrus (in females)
  • Genital irritation (cattle)
  • Decreased milk flow (cattle)
  • Follicular cysts (cattle)

注意事項

Use with extreme caution in small animals due to the high risk of blood dyscrasias (bone marrow depression), which are more prevalent in older animals and at higher dosages. Toxicity can progress to fatal aplastic anemia.

In cows with a prolonged corpus luteum, rule out endometritis or pregnancy before use.

Do not use in ferrets due to extreme sensitivity to estrogen-induced bone marrow toxicity.

医薬品相互作用

Azole Antifungals (fluconazole, itraconazole, ketoconazole)

May increase estrogen levels due to CYP450 enzyme inhibition.

Corticosteroids

Enhanced glucocorticoid effects; estrogens may alter protein binding or decrease metabolism of corticosteroids.

Macrolide Antibiotics (erythromycin, clarithromycin)

May increase estrogen levels.

Phenobarbital

May decrease estrogen activity via hepatic enzyme induction.

Rifampin

May decrease estrogen activity via hepatic enzyme induction.

St. John's Wort

May decrease estrogen activity.

Warfarin

Oral anticoagulant activity may be decreased; dosage adjustments may be necessary.

監視

  • Packed Cell Volumes (PCV)
  • White blood cell counts (CBC)
  • Platelet counts (Baseline, one month after therapy, and repeated two months after cessation if abnormal)
  • Liver function tests

薬物動態

吸収

Esterified estrogens (like estradiol cypionate) have delayed, prolonged absorption after IM administration in oil solutions.

分布

Distributed throughout the body and accumulates in adipose tissue.

代謝

Principally metabolized by the liver.

消失

Primarily excreted in the urine, but also excreted into the bile where most is reabsorbed from the GI tract (enterohepatic recirculation).

過剰投与

Acute overdosage reports in veterinary patients are rare, but chronic or high-dose exposure leads to severe adverse effects.

​Overdose manifestations:​

  • ​Small Animals:​ Severe bone marrow depression (thrombocytopenia, leukopenia, aplastic anemia), cystic endometrial hyperplasia, and pyometra.
  • ​Cattle:​ Prolonged estrus, genital irritation, decreased milk flow, precocious development, and follicular cysts.

Treatment is largely supportive. If bone marrow suppression occurs, aggressive supportive care (transfusions, broad-spectrum antibiotics) is required, though prognosis for aplastic anemia is poor.

製品

製剤

  • Injection (oil solution)
  • Tablets
  • Implants (veterinary beef cattle)

動物用医薬品

  • Estradiol-containing implants for use in beef cattle

ヒト用医薬品

  • Estradiol Cypionate in Oil for Injection: 5 mg/mL
  • Estradiol Valerate in Oil for Injection: 10 mg/mL, 20 mg/mL & 40 mg/mL
  • Estradiol Tablets: 0.45 mg, 0.5 mg, 0.9 mg, 1 mg, 1.5 mg, 1.8 mg & 2 mg micronized estradiol

規制ステータス

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

保管・安定性

Store in light-resistant containers at temperatures of less than 40°C, preferably at room temperature (15-30°C); avoid freezing. Do not mix with other medications.

飼主向け情報

  • ​重大なリスク警告​：この薬は犬や猫の骨髄に深刻で、時には致命的なダメージを与える可能性があるため、現在ではほとんど使用されていません。
  • ペットに​歯茎の蒼白、異常なあざ、皮膚の赤い斑点、極度の疲労​などの貧血や出血の兆候が見られた場合は、​すぐに​獣医師に連絡してください。
  • 重篤な子宮感染症（​子宮蓄膿症​）の兆候に注意してください。異常な多飲多尿、無気力、陰部からの分泌物などが含まれ、治療後1〜6週間で発生する可能性があります。
  • 重大な胎児の奇形を引き起こすため、​妊娠中の動物には絶対に使用しないでください​。
  • ​食用動物への使用禁止​：人間の食用となる動物には絶対に使用してはなりません。

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。