プロカルバジン
**プロカルバジン**は非定型アルキル化抗悪性腫瘍薬であり、獣医療においては主に犬や猫の再発性または難治性リンパ腫に対する**MOPP**または**LOPP**化学療法プロトコルの一部として使用されます。 > **臨床上のポイント**：他の多くの抗がん剤とは異なり、プロカルバジンは脂溶性が高く、**血液脳関門（BBB）**を容易に通過します。このユニークな特性により、中枢神経系（CNS）の腫瘍や炎症性疾患、特に犬の**肉芽腫性髄膜脳炎（GME）**の治療において高い有効性を示します。 さらに、プロカルバジンは弱い**モノアミン酸化酵素阻害（MAOI）**作用を持つため、高血圧クリーゼを防ぐために、他の薬物（三環系抗うつ薬、交感神経模倣薬など）や特定の食事（チラミンを多く含む食品）との併用には厳重な注意が必要です。
作用機序: Procarbazine is a prodrug that requires hepatic and renal metabolism to become active. Its exact mechanism is complex and multifaceted: - **Hepatic Metabolism** → Procarbazine is oxidized to **azo-procarbazine** and further metabolized to yield **methyl radicals** and **hydrogen peroxide**. - **DNA Alkylation** → The methyl radicals directly methylate nucleic acids, causing DNA strand breakage and inhibiting the synthesis of DNA, RNA, and proteins. - **Oxidative Stress** → The auto-oxidation process generates hydrogen peroxide, which directly induces oxidative damage to DNA. - **MAO Inhibition** → As an off-target effect, it inhibits the enzyme **monoamine oxidase (MAO)**, preventing the breakdown of monoamines like serotonin, norepinephrine, and dopamine.
動物種別の用量
- MOPP lymphoma rescue · 50 mg/m2 or 10 mg (total dose per cat) · PO · once daily for the first 14 days of the treatment cycle · 14 days · Used as part of a protocol in combination with other antineoplastic agents.
- Lymphoma rescue (MOPP protocol) · 50 mg/m2 · PO · once daily for the first 14 days of the treatment cycle · 14 days · Used as part of a protocol in combination with other antineoplastic agents.
- Granulomatous meningoencephalitis (GME) · 25-50 mg/m2 · PO · once daily initially, then every other day · Initially given with prednisone treatment. After the first month, attempt to reduce to every other day. Monitor CBC weekly for the first month.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Known hypersensitivity to procarbazine
- Inadequate bone marrow reserve
有害事象
- Nausea and vomiting
- Hepatotoxicity
- Myelosuppression (thrombocytopenia, leukopenia)
- Hemorrhagic gastritis
- CNS effects (sedation, agitation)
- Peripheral neuropathy (loss of tendon reflexes, paresthesias, myalgia)
薬物相互作用
- Alcohol/Ethanol · May cause severe nausea and vomiting (disulfiram-like reaction).
- CNS Depressant Drugs (barbiturates, opiates, antihistamines, phenothiazines) · Procarbazine can cause CNS depression; concurrent use can lead to severe depression. Coma and death have been reported with opiates.
- Foods with high tyramine content (aged cheese, yogurt) · Serious hypertension may result due to procarbazine's MAOI activity.
- Sympathomimetics (phenylpropanolamine, etc.) · Serious hypertension may result due to procarbazine's MAOI activity.
- Tricyclic Antidepressants (clomipramine, amitriptyline) · Do not use concurrently due to MAOI activity; risk of serotonin syndrome or hypertensive crisis.
モニタリング
- Baseline: CBC, hepatic and renal function, urinalysis
- Repeat CBC at least once weekly for the first month of treatment, and then monthly thereafter
- Monitor for signs of neurotoxicity or severe GI distress
過量投与
The LD50 for laboratory animals ranges from 150 mg/kg (rabbits) to 1.3 grams/kg (mice). - **Treatment**: Treat overdoses aggressively to remove the drug from the gut if the overdose occurred within an hour or two (e.g., induction of emesis, activated charcoal). - **Anticipated Effects**: Extensions of the drug's adverse effect profile, including severe GI distress, profound bone marrow suppression, and CNS effects. - **Management**: Monitor closely and provide supportive care as necessary. Contact an animal poison control center for further guidance.
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。