クロプロステノールナトリウム
クロプロステノールナトリウムは、強力な**黄体退行**作用を持つ合成**プロスタグランジンF2α（PGF2α）アナログ**であり、獣医療で広く使用されています。天然のジノプロストと構造的に関連していますが、より強力で作用時間が長いです。 * **大動物：** 牛、馬、豚の繁殖において、発情同期化、分娩誘起、および黄体嚢腫、ミイラ化胎子、慢性子宮内膜炎などの生殖器疾患の管理に不可欠です。 * **小動物：** 犬では、妊娠中絶や開放性子宮蓄膿症の内科的治療として適応外使用されます。 **臨床のポイント：** 合成アナログであるため、馬では天然のPGF2α（ジノプロスト）と比較して全身性の副作用が少ないことが多いですが、犬では依然として顕著なコリン作動性副作用（アトロピンなどの抗コリン薬の事前投与で軽減可能）が見られる場合があります。
作用機序: Cloprostenol acts as a potent agonist at **prostaglandin F (FP) receptors**. * **Luteolysis:** Binds to FP receptors on the **corpus luteum (CL)** → induces rapid functional and structural regression (luteolysis) → sharp decline in **progesterone** production. This drop in progesterone removes the negative feedback on the hypothalamus/pituitary, allowing a return to estrus, or induces abortion/parturition depending on the stage of gestation. * **Myometrial Contraction:** Directly stimulates FP receptors on **uterine smooth muscle** → increases intracellular calcium → powerful, rhythmic uterine contractions (ecbolic effect). * **Cervical Relaxation:** Concurrently promotes relaxation and dilation of the cervix, facilitating the expulsion of uterine contents (e.g., fetus, purulent material in pyometra).
動物種別の用量
- To induce parturition in does · 62.5-125 micrograms · IM · once · Give at 144 days of gestation in early morning. Deliveries will peak at 30-35 hours after injection. Maintain goat in usual surroundings and minimize outside disturbances.
- To treat pseudopregnancy (hydrometra/mucometra) · 125 micrograms · IM · once
- For treatment of pyometra · 500 micrograms · IM · once · Up to 97% efficacy.
- For pyometra or chronic endometritis, mummified fetus, luteal cysts · 500 micrograms · IM · once · Manual assistance may be required to remove mummified fetus from vagina.
- For unobserved or undetected estrus in cows with continued ovarian cyclicity and a mature corpus luteum · 500 micrograms · IM · once · Estrus should commence in 2-5 days at which time the animal may be inseminated. If estrus detection is not possible, inseminate twice at 72 and 96 hours post injection.
- For abortion, from one week after mating to approximately the 150th day of gestation · 500 micrograms · IM · once · Abortion generally takes place in 4-5 days after injection.
- For controlled breeding (Single injection method) · 500 micrograms · IM · once · Use only animals with mature corpus luteum. Inseminate at usual time after detecting estrus, or once at 72 hours, or twice at 72 and 96 hours post injection.
- For controlled breeding (Double injection method) · 500 micrograms · IM · Repeat dose 11 days later · Estrus should occur in 2-5 days after second injection.
投与経路
禁忌
- Pregnancy (when abortion or induced parturition are not desired)
- Intravenous (IV) administration
有害事象
- Increased salivation (dogs)
- Tachycardia (dogs)
- Increased urination and defecation (dogs)
- Gagging and vomiting (dogs)
- Ataxia and mild depression (dogs)
- Sweating (horses)
- Cramping and loose stools (horses)
- Increased risk of dystocia if used after 5th month of gestation (cattle)
薬物相互作用
- Oxytocic agents · Activity may be enhanced by cloprostenol
モニタリング
- Resolution of clinical signs (e.g., clearance of pyometra)
- Estrus behavior and timing
- Confirmation of pregnancy termination/abortion
- Adverse cholinergic effects in dogs (salivation, vomiting, heart rate)
過量投与
In **cattle**, doses of 50 and 100 times those recommended may cause signs of uneasiness, slight frothing, and milk let-down. In **small animals**, overdoses of cloprostenol or other synthetic prostaglandin F2α analogs reportedly can result in severe shock and death.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。