酢酸メドロキシプロゲステロン
Medroxyprogesterone Acetate
17-hydroxy-6alpha-methylpregn-4-ene-3,20-dione acetate
別名: Depo-Provera · depo-subQ provera 104 · MPA · MAP · acetoxymethylprogesterone · medroxyprogesteroni acetas · methylacetoxyprogesterone · metipregnone · NSC-26386
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
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 |
|---|---|---|---|---|---|
| Apparent luteal insufficiency in bitches | 0.1 mg/kg PO once daily | PO | q24h | Discontinue several days prior to expected due date | 🌎 NA |
| Long-term reproductive control | 2.5-3 mg/kg IM q5 months | IM | q5 months | — | 🌎 NA |
| Adjunctive treatment of aggressive behaviors | 10 mg/kg IM or SC | IM/SC | As necessary | — | 🌎 NA |
| Young German shepherd dwarfs | 2.5-5 mg/kg initially at 3 week intervals and subsequently at 6 week intervals | IM/SC | q3w initially, then q6w | — | 🌎 NA |
| Benign prostatic hypertrophy | 0.3 mg/kg SC once | SC | Once | Effects last approximately 10 months | 🌎 NA |
| Progestin-responsive dermatitis | 20 mg/kg IM | IM | May repeat in 3-6 months if needed | — | 🌎 NA |
- Apparent luteal insufficiency in bitches: Potential benefits outweigh risks in second half of pregnancy, though fetal deformities are possible.
- Adjunctive treatment of aggressive behaviors: Works best with behavior modification. For inter-male aggression: do not exceed 3 treatments per year.
- Young German shepherd dwarfs: Has resulted in some increase in body size and adult hair coat development.
- Benign prostatic hypertrophy: Best used to maintain breeding potential for short time prior to castration; use with caution.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Behavioral disorders (reduce marking in neutered males) | 5-20 mg/kg SC or IM three to four times yearly | SC/IM | 3-4 times yearly | — | 🌎 NA |
| Feline psychogenic alopecia and dermatitis | 75-150 mg IM or SC | IM/SC | Repeat as necessary, but never more often than every 2-3 months | — | 🌎 NA |
| Progestagen-responsive dermatitis | 50-100 mg IM | IM | May repeat in 3-6 months if needed | — | 🌎 NA |
| Recurrent abortion secondary to progesterone-deficiency | 1-2 mg/kg IM once weekly | IM | q7d | Stop treatment 7-10 days prior to parturition | 🌎 NA |
| Long-term reproductive control | 2.5-5 mg PO once weekly; 25 mg injected every 6 months to postpone estrus | PO/IM/SC | q7d (PO) or q6mo (Injection) | — | 🌎 NA |
| Long-term reproductive control | 2 mg/kg IM q5 months | IM | q5 months | — | 🌎 NA |
- Behavioral disorders (reduce marking in neutered males): Use when all other drugs have been unsuccessful.
鳥
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Antipruritic and to suppress ovulation | 0.025-1 mL (3 mg/100 grams body weight) IM once every 4-6 weeks | IM | q4-6w | — | 🌎 NA |
- Antipruritic and to suppress ovulation: May cause obesity, fatty liver, polydipsia/polyuria and lethargy if used repeatedly.
馬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Management of spring transition, prevention of estrus behavior, induction of estrous cycle synchrony, pregnancy maintenance, modification of stallion behavior | 500 to 800 mg IM | IM | Interval varies | Most injections last 2 to 3 months | 🌎 NA |
- Management of spring transition, prevention of estrus behavior, induction of estrous cycle synchrony, pregnancy maintenance, modification of stallion behavior: Will not prevent pregnancy loss and does not stop cyclicity.
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。
概要
酢酸メドロキシプロゲステロン（MPA）は、プロゲステロンの強力な合成プロゲスチン誘導体です。
歴史的に、獣医学では行動修正（徘徊、オス間の攻撃行動、スプレー行動など）や皮膚疾患（猫の心因性脱毛症など）に使用されてきました。しかし、重篤な副作用のリスクが高いため、現在では使用が大幅に減少しています。
臨床のポイント: 行動問題に対しては、より安全な代替治療（SSRI、TCA、または外科的避妊・去勢手術など）が強く推奨されます。MPAは、妊娠犬の黄体機能不全、良性前立腺肥大の短期管理、ジャーマン・シェパードの下垂体性小人症など、特定の生殖関連の適応症に現在でも時折使用されます。全身への影響が大きいため、内分泌および生殖器系の合併症という重大なリスクと潜在的な利益を慎重に比較検討する必要があります。
作用機序
MPA mimics endogenous progesterone by binding to intracellular progesterone receptors, translocating to the nucleus, and altering gene transcription. It transforms the proliferative endometrium into a secretory endometrium and inhibits spontaneous uterine contractions.
- Endocrine/Reproductive: Exerts negative feedback on the hypothalamus and pituitary, decreasing GnRH → suppressing FSH and LH release, thereby inhibiting estrus and spermatogenesis. It also possesses anti-estrogenic properties and decreases plasma testosterone.
- Glucocorticoid Activity: MPA has significant intrinsic affinity for glucocorticoid receptors, leading to profound suppression of the hypothalamic-pituitary-adrenal (HPA) axis (decreased ACTH and cortisol release).
- Metabolic Effects: Induces peripheral insulin resistance, which can precipitate diabetes mellitus.
- Growth Hormone: In dogs, progestins can stimulate the mammary glands to produce growth hormone, potentially leading to acromegaly.
安全性・警告
禁忌
- Pre-pubescent cats or dogs
- Diabetes mellitus
- Pseudopregnant bitches
- Females in diestrus or with prolonged heat
- Uterine hemorrhage or discharge
- Pregnancy (unless specifically treating hypoluteoidism)
有害事象
- Increased thirst (polydipsia) and urination (polyuria)
- Increased appetite (polyphagia) and weight gain
- Depression, lethargy, and personality changes
- Adrenocortical depression (HPA axis suppression)
- Mammary changes (enlargement, milk production, neoplasia)
- Diabetes mellitus
- Pyometra / Cystic endometrial hyperplasia
- Temporary inhibition of spermatogenesis
- Permanent local alopecia, skin atrophy, and depigmentation (with SC injection)
- Acromegaly (in dogs)
注意事項
Progestagen therapy can cause serious adverse effects; safer alternative treatments should be considered first. Do not use prior to puberty as severe mammary hypertrophy or subclinical uterine/endocrine conditions may result. Because this drug can suppress adrenal function, exogenous steroids may be needed during times of stress (e.g., surgery, trauma). Prior to reproductive use, perform a thorough history, physical exam, mammary palpation, and vaginal smear to rule out diestrus, estrus, or mammary nodules.
医薬品相互作用
May decrease medroxyprogesterone effects
May increase medroxyprogesterone metabolism
May decrease progestin activity due to microsomal enzyme induction and increased progestin metabolism
監視
- Weight
- Blood glucose (draw baseline before therapy and monitor periodically)
- Mammary gland development
- Adrenocortical function
- Clinical efficacy
薬物動態
半減期
分布
Can be detected in maternal milk.
代謝
Hepatic metabolism (susceptible to microsomal enzyme induction).
過剰投与
No specific reports on inadvertent acute overdosage were located. Overdose is expected to manifest as an exaggeration of adverse effects, including profound adrenal suppression, lethargy, metabolic derangements (hyperglycemia), and reproductive tract changes. Treatment should be supportive and symptomatic.
製品
製剤
- Tablets
- Injection (suspension)
ヒト用医薬品
- Medroxyprogesterone Acetate Tablets (scored): 2.5 mg, 5 mg & 10 mg (Provera)
- Medroxyprogesterone Acetate Injection: 104 mg (160 mg/mL) in 0.65 mL prefilled syringes; 150 mg/mL in 1 mL vials; 400 mg/mL in 2.5 mL & 10 mL vials and 1 mL U-ject (depo-subQ provera 104, Depo-Provera)
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
Suspensions for injection should be stored at room temperature (15-30°C); avoid freezing and temperatures above 40°C. Tablets should be stored in well-closed containers at room temperature.
飼主向け情報
重要: この薬には重大なリスクが伴うため、通常はより安全な代替治療が効果を示さなかった場合にのみ使用されます。
- 注意深く観察してください: 喉の渇き、尿量の増加、食欲の増加が見られないか確認してください。これらは重大な副作用である糖尿病の初期症状の可能性があります。
- 乳腺の腫れ、しこり、乳汁の分泌などの変化がないか注意してください。
- 避妊手術をしていないメスの場合、重篤な子宮感染症（子宮蓄膿症）の兆候（無気力、嘔吐、食欲低下、膣からの分泌物など）がないか監視してください。これらの症状が現れた場合は、直ちに獣医師の診察を受けてください。
- 皮下注射で投与した場合、注射部位に永久的な脱毛、皮膚の萎縮、または変色が生じる可能性があります。
- この薬の服用中、ペットに性格の変化、無気力、または体重増加が見られることがあります。
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。