環戊丙酸雌二醇
環戊丙酸雌二醇（Estradiol Cypionate）是一種長效的天然雌激素酯類衍生物。過去常被用作小動物的墮胎藥（錯配後的避孕），但由於其具有引發**致命性骨髓抑制**（再生不良性貧血）及**子宮蓄膿**的高風險，目前多數獸醫繁殖學專家已不再推薦使用，臨床上多偏好更安全有效的替代方案。 > **臨床重點**：美國FDA已明令禁止將此藥物用於產食動物，任何針對此類動物的給藥或調劑皆屬違法。
作用機制: 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.
各物種劑量
- Pregnancy avoidance after mismating · 250 micrograms/kg (0.25 mg/kg) IM once 6 days after coitus; or 0.25 mg/cat IM at 40 hours after coitus · IM · once · Rarely used for this indication today as there are safer, more effective treatments.
- Any · Illegal · The FDA has stated that the use of ECP in food-producing animals is illegal.
- To enhance estrus behavior and receptivity in ovariectomized mares · 5-10 mg (total dose) IM once · IM · once
- Treatment of mares with estrogen-responsive incontinence · 4-10 micrograms/kg estradiol cypionate IM daily for three days and then every other day · IM · daily then q48h · 3 days then ongoing · Some mares will improve, but does not 'cure'.
- Pregnancy avoidance after mismating · 44 micrograms/kg (0.044 mg/kg) IM once; during day 4 estrus to day 2 of diestrus · IM · once · Rarely used for this indication today as there are safer, more effective treatments. Toxic at >=100 micrograms/kg.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- 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)
不良反應
- 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)
藥物相互作用
- 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.
監測
- 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
過量
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.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。