ジノプロストトロメタミン
ジノプロストトロメタミンは、天然に存在するプロスタグランジンF2α（PGF2α）のトロメタミン塩であり、複数の動物種の獣医繁殖医学で広く使用されています。 * **大動物**：主に牛、馬、豚、小型反芻動物における発情同期化、鈍性発情の治療、子宮蓄膿症の治療、および堕胎薬や分娩誘発薬としての黄体退行薬として使用されます。 * **小動物**：犬や猫における堕胎薬として、また開放鎖骨型子宮蓄膿症の補助的内科療法として適応外使用されます。 > **臨床のポイント**：ジノプロストは犬において治療域が非常に狭いです。LD50は推奨治療用量のわずか約5倍であるため、正確な投与と慎重なモニタリングが不可欠です。子宮蓄膿症の新しいプロトコルでは、安全性の観点からアグレプリストンとクロプロステノールまたはミソプロストールの併用が好まれることが多くなっています。
作用機序: Dinoprost acts directly as a **prostaglandin F2alpha (PGF2α)** analog. * **Luteolysis**: Binds to specific PGF2α receptors on the corpus luteum → inhibits steroidogenesis → induces structural and functional regression of the corpus luteum (luteolysis) → rapid decline in serum progesterone levels. * **Myometrial Contraction**: Directly stimulates myometrial smooth muscle activity → increases intracellular calcium → induces strong uterine contractions. * **Cervical Relaxation**: Promotes relaxation and dilation of the cervix, facilitating the expulsion of uterine contents (fetus or purulent material in pyometra).
動物種別の用量
- Estrus synchronization · 8 mg IM on day 5 of estrous cycle and repeat in 11 days · IM · twice, 11 days apart · 11 days
- Abortifacient (first two months of pregnancy) · 10-15 mg IM · IM · once · once · Abortion takes place within 72 hours.
- Estrus synchronization · 8 mg IM on day 4 of estrous cycle and repeat in 11 days · IM · twice, 11 days apart · 11 days
- Pseudopregnancy (hydrometra/mucometra) · 5 mg IM once · IM · once · once
- Abortifacient · 5-10 mg IM throughout entire pregnancy · IM · once · once · Abortion takes place in 4-5 days.
- Induce parturition · 2.5-20 mg on days 144-149 · IM · once · once · Higher dosage (20 mg) yields more predictable interval to delivery.
- Treatment of pyometra · Initially 0.1 mg/kg SC, then 0.25 mg/kg SC once a day for 5 days · SC · once daily · 6 days total · Give bactericidal antibiotics concurrently. Not recommended in animals >8 yrs old.
- Abortifacient · 2 mg (total dose) per cat IM once a day beginning at day 33 · IM · once daily · Not specified · Side effects include prostration, vomiting and diarrhea.
投与経路
禁忌
- Pregnancy (unless abortion or induced parturition is desired)
- Intravenous (IV) administration
- Animals with bronchoconstrictive respiratory disease (e.g., asthma, 'heaves' in horses)
- Mares with acute or subacute disorders of the vascular system, GI tract, respiratory system, or reproductive tract
- Camelids (associated with acute toxicity and death)
- Relative contraindication: Closed-cervix pyometra
- Extreme caution in elderly (>8 years old) or debilitated animals, or those with severe cardiopulmonary, renal, or hepatic disease
有害事象
- Dogs/Cats: Abdominal pain, emesis, defecation, urination, pupillary dilation followed by constriction, tachycardias, restlessness, anxiety, fever, hypersalivation, dyspnea, panting. Fatalities are possible (especially in dogs). Cats may exhibit intense grooming and vocalization.
- Cattle: Infection at injection site, salivation, hyperthermia (especially at higher doses).
- Swine: Erythema, pruritus, urination, defecation, slight ataxia, hyperpnea, dyspnea, nesting behavior, abdominal muscle spasms, tail movements, increased vocalization, salivation.
- Horses: Transient decreased body temperature, sweating. Less frequently: increased respiratory and heart rates, ataxia, abdominal pain, lying down.
薬物相互作用
- Other oxytocic agents · Activity may be enhanced by dinoprost.
- Progestins · Reduced effect of dinoprost would be expected with concomitant administration.
モニタリング
- Cardiorespiratory effects (especially in dogs and cats, particularly after higher dosages)
- Adverse effects (vomiting, diarrhea, hyperthermia, distress)
- Efficacy of treatment (e.g., ultrasound for pyometra resolution or pregnancy termination, observation for estrus)
過量投与
Dogs are highly sensitive to the toxic effects of dinoprost. The LD50 in the bitch is reported to be **5.13 mg/kg SC**, which is only about 5 times greater than the recommended dose used by some clinicians. In large animals (cattle, swine, horses), overdose quantities (e.g., 5-10X recommended doses) result in exaggerated adverse effects such as hyperthermia, vomiting, and severe abdominal cramping. **Treatment**: If clinical signs are severe in any species, immediate supportive and symptomatic therapy is recommended.
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。