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クロラゼプ酸

Clorazepate

Clorazepate dipotassium

ベンゾジアゼピン系（抗不安薬、鎮静睡眠薬、抗てんかん薬）PO犬猫

別名: Tranxene-SD · Gen-Xene · Tranxene T-tab · Abbott-35616 · AH-3232 · 4306-CB · clorazepic acid · dipotassium clorazepate · dikalii clorazepas

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

1-2 mg/kg PO q12h, but may need to divide q12h dose and give q8h to minimize adverse effects and maintain therapeutic levelsPO· q8-12h
— 🐕

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
Adjunctive medication in the treatment of seizures (in combination with phenobarbital)1-2 mg/kg PO q12h, but may need to divide q12h dose and give q8h to minimize adverse effects and maintain therapeutic levelsPOq8-12h—🌎 NA
Adjunctive medication in the treatment of seizures (in combination with phenobarbital)0.5-1 mg/kg PO q8hPOq8h—🌎 NA
Adjunctive medication in the treatment of seizures1-2 mg/kg PO q12hPOq12h—🌎 NA
Adjunctive medication in the treatment of seizures2-4 mg/kg PO twice daily, some dogs may require three times dailyPOq8-12h—🌎 NA
Third-line agent for seizures1-2 mg/kg PO q8-12hPOq8-12h—🌎 NA
Management of cluster seizures0.5-2 mg/kg two to three times dailyPOq8-12h48-96 hours🌎 NA
Adjunctive therapy for fears and phobias11.25-22.5 mg per dog PO once to twice dailyPOq12-24h—🌎 NA
Adjunctive therapy for fears and phobias22.5 mg for large dogs, 11.25 mg for medium dogs and 5.6 mg for small dogs POPOprn—🌎 NA
Adjunctive therapy for fears and phobias0.55-2.2 mg/kg PO as needed up to q8hPOup to q8h—🌎 NA
Adjunctive therapy for fears and phobias0.2-1 mg/kg PO q12-24hPOq12-24h—🌎 NA
  • Adjunctive medication in the treatment of seizures (in combination with phenobarbital): No advantage gained with using sustained release products. May affect phenobarb levels; monitor 2 and 4 weeks later.
  • Management of cluster seizures: Give immediately after first seizure and stop after 48-96 hours. Used only during seizure activity, not as maintenance.
  • Adjunctive therapy for fears and phobias: Recommends the sustained-delivery product (Tranxene-SD).
  • Adjunctive therapy for fears and phobias: Using sustained delivery product. Adjust dosage according to dog's response.
  • Adjunctive therapy for fears and phobias: Titrate to clinical sedation; dose may vary for individual dogs.

猫

適応用量経路頻度期間地域
Anxiolytic or for compulsive behaviors0.2-0.5 mg/kg PO q12-24hPOq12-24h—🌎 NA
Alternative drug to phenobarbital for seizures3.75-7.5 mg (total dose per cat) PO once to twice dailyPOq12-24h—🌎 NA
  • Alternative drug to phenobarbital for seizures: Similar precautions are necessary as described for diazepam use in cats (risk of hepatic necrosis).

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。

診察中ですか？VetSheet の AI が薬剤・用量・投与期間を構造化された診察記録に直接記入します。VetSheet の仕組みを見る

概要

クロラゼプ酸は​ベンゾジアゼピン系​の薬物で、獣医療では主にてんかんの補助治療や、不安・恐怖に関連する行動障害の治療に使用されます。

  • ​臨床のポイント​: 本剤はプロドラッグであり、吸収される前に胃酸によって速やかに活性代謝物である​ノルジアゼパム​に変換される必要があります。
  • 犬では難治性てんかんに対してフェノバルビタールと併用されることがよくあります。抗てんかん作用に対する耐性が生じることがありますが、クロナゼパムよりも耐性形成が遅いと報告されています。
  • 猫では抗不安薬として、またてんかん管理においてフェノバルビタールの代替薬として使用されることがありますが、経口ベンゾジアゼピン系薬物は猫において特異体質性の肝毒性を引き起こすリスクがあるため、慎重な投与が求められます。

作用機序

Benzodiazepines exert their effects by enhancing the inhibitory activity of ​gamma-aminobutyric acid (GABA)​ in the central nervous system.

  • Mechanism: They bind to specific allosteric sites on the GABA-A receptor complex → increases the frequency of chloride channel opening → cellular hyperpolarization → decreased neuronal excitability.
  • This depression of subcortical CNS levels (primarily limbic, thalamic, and hypothalamic) produces the characteristic anxiolytic, sedative, skeletal muscle relaxant, and anticonvulsant effects.
  • Other postulated mechanisms include antagonism of serotonin and diminished release or turnover of acetylcholine in the CNS.

安全性・警告

禁忌

  • Hypersensitivity to benzodiazepines
  • Significant liver disease/dysfunction
  • Acute narrow angle glaucoma
  • Fear-induced aggression (relative contraindication; may disinhibit bite inhibition)

有害事象

  • Sedation (most common)
  • Ataxia
  • Physical dependence (with chronic use)
  • Acute hepatic necrosis (idiosyncratic in cats)
  • Paradoxical excitation or disinhibition of aggression

注意事項

Use with extreme caution in aggressive animals, particularly those with fear-induced aggression, as benzodiazepines can disinhibit anxiety-based bite inhibition and provoke attacks. Benzodiazepines may exacerbate myasthenia gravis. Safe use during pregnancy is not established (FDA Category D in humans; teratogenic effects noted in lab animals). The active metabolite, nordiazepam, is distributed into milk and may affect nursing neonates. Abrupt withdrawal after chronic use can precipitate severe rebound seizures.

医薬品相互作用

Azole Antifungals (itraconazole, ketoconazole)

May increase serum levels of benzodiazepines by inhibiting their metabolism.

Cimetidine

May decrease the metabolism of benzodiazepines, leading to prolonged effects.

CNS Depressants (barbiturates, narcotics, anesthetics)

Additive CNS depression; may cause profound sedation or respiratory depression.

Erythromycin

May decrease the metabolism of benzodiazepines.

Phenobarbital

Complex interaction: Clorazepate may initially increase phenobarbital serum levels. Over time, clorazepate levels may decrease, leading to decreased phenobarbital levels. Requires close monitoring.

Phenytoin

May decrease clorazepate concentrations.

Rifampin

May induce hepatic microsomal enzymes and decrease the pharmacologic effects of benzodiazepines.

監視

  • Clinical efficacy (seizure frequency or behavioral improvement)
  • Adverse effects (sedation, ataxia)
  • Liver enzymes (especially critical in cats due to risk of acute hepatic necrosis)
  • Phenobarbital serum levels (if used concurrently, monitor at 2 and 4 weeks after adding clorazepate)

薬物動態

吸収

In dogs, peak serum levels generally occur within 1-2 hours.

分布

Volume of distribution is about 1.8 L/kg after multiple dosing in dogs. Nordiazepam is distributed into milk.

代謝

Clorazepate is a prodrug that is rapidly decarboxylated in the acidic environment of the stomach to nordiazepam (active) and other metabolites.

消失

Eliminated primarily via hepatic metabolism and subsequent renal excretion of metabolites.

過剰投与

When used alone, clorazepate overdoses are generally limited to significant CNS depression (confusion, coma, decreased reflexes, profound sedation).

  • Treatment: Consists of standard protocols for removing and/or binding the drug in the gut (e.g., emesis if asymptomatic and recent, activated charcoal) and supportive systemic measures.
  • The use of analeptic agents (CNS stimulants such as caffeine, amphetamines) is generally not recommended.
  • Flumazenil (a specific benzodiazepine reversal agent) may be considered for very serious, life-threatening overdoses.

製品

製剤

  • Capsules
  • Sustained-release tablets

ヒト用医薬品

  • Clorazepate Dipotassium Tablets: 3.75 mg, 7.5 mg, & 15 mg (Tranxene T-tab; generic)

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

Clorazepate dipotassium is unstable in the presence of water. Keep the desiccant packets in the original container of the capsules and tablets. Consider adding a desiccant packet to the prescription vial when dispensing large quantities.

飼主向け情報

​重大な警告​: 急に投薬を中止しないでください。突然の休薬は、生命を脅かす重篤な離脱性けいれん発作を引き起こす恐れがあります。投薬を中止する必要がある場合は、必ず獣医師に相談し、徐々に減量する計画を立ててください。

  • ​規則正しい投薬が重要​: 抗てんかん治療が失敗する主な原因は、投薬忘れです。毎日同じ時間に投薬してください。
  • ​猫の飼い主様へ​: 猫が食欲不振、嘔吐、または白目や歯茎の黄染（黄疸）を示した場合は、重篤な肝障害のサインである可能性があるため、​直ちに​獣医師にご連絡ください。
  • ​副作用​: 特に投薬開始初期には、ペットが眠そうにしたり、ふらついたり、動きがぎこちなくなったりすることがあります。これらは体が薬に慣れるにつれて改善することが多いです。
  • ​保管方法​: 本剤は湿気に触れると急速に劣化するため、乾燥剤が入った元の容器のまま保管してください。

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