達卡巴仁 / 達卡巴肼
達卡巴仁（常被稱為 **DTIC**）是一種注射用**抗腫瘤藥物**，在獸醫腫瘤學中主要用於治療犬隻復發性淋巴瘤、軟組織肉瘤和黑色素瘤。 **臨床要點：** * 達卡巴仁是一種**前驅藥（prodrug）**，需要經過肝臟活化才能發揮其細胞毒性作用。 * **不建議用於貓**，因為目前尚不清楚貓的肝臟是否能充分將其代謝為活性形式，這使得該藥物在貓體內的療效和安全性極難預測。 * 它是一種強烈的**發泡劑（vesicant）**；藥物外滲會導致嚴重的組織壞死。必須透過放置完美的靜脈留置針給藥，通常建議以稀釋後的慢速輸注方式進行。
作用機制: Dacarbazine is a prodrug that undergoes hepatic N-demethylation (likely via **cytochrome P450** enzymes) to form an active intermediate, which then degrades to form **reactive carbonium ions**. * **Alkylating Activity:** These carbonium ions act as alkylating agents → cross-link DNA strands → interfere with DNA transcription and replication. * **Antimetabolite Activity:** It also inhibits the incorporation of purine nucleosides into DNA. * It possesses minimal immunosuppressant activity and is generally considered **cell cycle-phase nonspecific**.
各物種劑量
- Relapsed lymphoma, soft tissue sarcomas, melanoma · 800-1000 mg/m2 · IV · every 2-3 weeks · over 5-8 hours · NOT mg/kg. Depending on the protocol used.
- Relapsed Lymphoma (Rescue Protocol) · 800-1000 mg/m2 · IV · every 3 weeks · as determined by oncologist · Administer as a slow IV infusion (over several hours) to minimize adverse effects. Pre-medicate with antiemetics.
- Relapsed Lymphoma (Alternative schedule) · 200 mg/m2 · IV · sid · for 5 consecutive days · Repeat cycle every 3 weeks.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Cats (due to unknown hepatic metabolism capabilities)
- Patients with known hypersensitivity to the drug
- Pregnancy (teratogenic)
- Pre-existing severe myelosuppression
- Severe hepatic dysfunction
- Pregnancy and lactation
- Known hypersensitivity
不良反應
- Severe gastrointestinal toxicity (vomiting, anorexia, diarrhea) - often dose-limiting
- Bone marrow suppression (leukopenia, thrombocytopenia) - nadir occurs several weeks post-treatment
- Severe tissue damage and pain (if extravasated)
- Venous spasm and phlebitis during IV administration
- Alopecia (rare)
- Hepatotoxicity (rare)
- Renal impairment (rare)
- Photosensitivity (rare)
- Severe nausea and vomiting
- Myelosuppression (neutropenia, thrombocytopenia)
- Tissue necrosis if extravasated
- Hepatotoxicity
- Lethargy
- Anorexia
藥物相互作用
- Myelosuppressive drugs (e.g., other antineoplastics, chloramphenicol, flucytosine, colchicine) · May cause additive myelosuppression when used concurrently with DTIC.
- Rifampin · May increase the hepatic metabolism of DTIC.
- Phenobarbital · May increase the hepatic metabolism of DTIC. · moderate
- Phenytoin · May increase the hepatic metabolism of DTIC.
- Other myelosuppressive agents · Additive bone marrow suppression · major
監測
- Efficacy (tumor response)
- CBC with differential and platelets (monitor for myelosuppression)
- Renal function tests
- Hepatic function tests
- IV catheter site for signs of extravasation during infusion
- Complete Blood Count (CBC) prior to each dose and at nadir (typically 7-14 days post-treatment)
- Liver function tests (ALT, AST, Bilirubin)
- Renal function
- IV catheter site for signs of extravasation
- Gastrointestinal signs (vomiting, diarrhea)
過量
Because of the severe toxic potential of this agent, iatrogenic overdoses must be strictly avoided. Recheck all dosage calculations carefully (ensure dosing is based on body surface area in mg/m2, not mg/kg). Overdose will likely result in profound, life-threatening bone marrow suppression and severe gastrointestinal toxicity. Treatment is supportive.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。