烯丙孕素
烯丙孕素（Altrenogest）是一種合成的口服孕激素，廣泛應用於獸醫繁殖醫學中。 - **馬**：用於抑制母馬發情以利於週期同步化，並在黃體素不足或患有胎盤炎的母馬中維持妊娠。 - **豬**：用於性成熟小母豬的發情同步化。 - **狗**：標示外使用於黃體功能不全及作為安胎藥物以預防早產。 > **臨床提示**：本藥物具高度脂溶性，極易穿透完整的人體皮膚吸收。對操作者（尤其是孕婦及有血栓或依賴雌激素疾病史的人）具有顯著的健康風險。
作用機制: Altrenogest acts as an agonist at **progesterone receptors**. - Transforms proliferative endometrium into secretory endometrium. - Enhances myometrial hypertrophy and inhibits spontaneous uterine contractions (tocolytic effect). - Exerts negative feedback on the hypothalamus and pituitary gland → inhibits secretion of **GnRH** → decreases release of pituitary gonadotropins (**FSH** and **LH**), thereby suppressing estrus and ovulation in a dose-dependent manner.
各物種劑量
- To suppress estrus for synchronization · 1 mL per 110 pounds body weight (0.044 mg/kg) · PO · once daily · 15 consecutive days · May administer directly on tongue using a dose syringe or on the usual grain ration.
- For prevention of abortion/pregnancy loss · 0.088 mg/kg · PO · once daily
- To maintain pregnancy in mares with deficient progesterone levels · 0.044 mg/kg · PO · once daily · Until day 60, 120, or end of pregnancy · Three options: 1) until day 60+ AND endogenous progesterone >4 ng/mL; 2) until day 120; 3) until end of pregnancy.
- To maintain pregnancy in mares with placentitis · 22-44 mg (total dose; 10-20 mL) · PO · daily
- To suppress estrus (long-term) · 0.044 mg/kg · PO · daily
- For synchronization of estrous in sexually mature gilts that have had at least one estrous cycle · 6.8 mL (15 mg) per gilt · PO · once daily · 14 consecutive days · Apply as a top-dressing on a portion of gilt's daily feed allowance. Estrous should occur 4-9 days after completing treatment.
- Luteal insufficiency · 2 mL per 100 lbs of body weight · PO · once daily · Document luteal insufficiency and rule out infectious causes. Best to avoid during first trimester. Monitor pregnancy with ultrasound. Monitor carefully for pyometra.
- Luteal insufficiency, pre-term labor · 0.1 mL per 10 lb body weight · PO · once daily
- To maintain pregnancy if tocolytics (e.g., terbutaline) do not control myometrial contractility · 0.088 mg/kg · PO · q24h · Must be withdrawn 2-3 days prior to predicted whelp date.
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
- Horses intended for food purposes
- Mares with chronic uterine infections
- Manufacturer lists pregnancy as a contraindication (though clinically used extensively to maintain pregnancy)
不良反應
- Minimal at labeled dosages
- Slight, sporadic elevations in Ca++, K+, alkaline phosphatase, and AST
- May exacerbate chronic uterine infections
- Risk of pyometra in dogs (due to exogenous progesterone effects)
藥物相互作用
- Rifampin · May decrease progestin activity if administered concomitantly due to microsomal enzyme induction and increased progestin metabolism.
監測
- Pregnancy viability (via ultrasound)
- Endogenous progesterone levels (if treating luteal deficiency)
- Signs of pyometra in dogs
過量
The LD50 of altrenogest is 175-177 mg/kg in rats. No specific information is available regarding the effects of an accidental acute overdose in horses or other veterinary species.
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。