阿糖胞苷
阿糖胞苷（通常稱為 **Ara-C**）是一種合成的嘧啶核苷抗代謝物，在獸醫學中主要用於治療犬貓的淋巴網狀內皮腫瘤、骨髓增生性疾病（白血病）和中樞神經系統淋巴瘤。 > **臨床重點：** 除了傳統的腫瘤學應用外，阿糖胞苷在獸醫神經學中被廣泛用作治療犬隻**不明原因腦膜腦炎 (MUE)** 和肉芽腫性腦膜腦炎 (GME) 的核心免疫抑制療法。由於其在連續靜脈輸注 (CRI) 或高劑量皮下注射方案下能夠穿透血腦屏障，因此對中樞神經系統發炎性疾病非常有效。
作用機制: Cytarabine is a cell-cycle phase-specific antimetabolite that acts principally during the **S-phase** (active DNA synthesis). * **Intracellular Conversion:** Cytarabine enters the cell and is phosphorylated into its active form, **cytarabine triphosphate**. * **Enzyme Inhibition:** This active metabolite competes with deoxycytidine triphosphate → incorporates into DNA → potently inhibits **DNA polymerase**. * **Result:** Inhibition of DNA synthesis and repair, leading to cell death in rapidly dividing cells. Under certain conditions, it may also block cells from transitioning from the G1 phase to the S phase.
各物種劑量
- Susceptible neoplastic diseases · 100 mg/m2 · IV/SC · continuous infusion over 2-3 days or divided and given IV or SC for 2-4 days · 2-4 days · Dosed in mg/m2 (NOT mg/kg). Cats are generally dosed similarly to dogs.
- Neoplastic diseases · 200-300 mg/m2 (usually 1-1.5 grams per horse per dose) · SC/IM/IV · every 1-2 weeks · Consultation with a veterinary oncologist is encouraged before use.
- Susceptible neoplastic diseases · 100 mg/m2 · IV/SC · continuous infusion over 2-3 days or divided and given IV or SC for 2-4 days · 2-4 days · Dosed in mg/m2 (NOT mg/kg). Use only as a general guide.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to cytarabine
- Pregnancy (potentially teratogenic and embryotoxic)
不良反應
- Myelosuppression (leukopenia, anemia, thrombocytopenia)
- Anorexia
- Nausea
- Vomiting
- Diarrhea
- Conjunctivitis
- Oral ulceration
- Neurotoxicity
- Hepatotoxicity
- Fever
- Anaphylaxis (rare)
藥物相互作用
- Digoxin · Cytarabine may decrease the amount of digoxin (tablets only) absorbed after oral dosing due to intestinal mucosa alterations; effect may persist for several days after cytarabine discontinuation.
- Flucytosine (5-FC) · Cytarabine may antagonize the anti-infective activity of flucytosine; monitor for decreased efficacy.
- Gentamicin · Cytarabine may antagonize the anti-infective activity of gentamicin; monitor for decreased efficacy.
監測
- Efficacy (tumor response or resolution of neurologic signs)
- Hemograms (mandatory; monitor for myelosuppression, nadir typically at 5-7 days)
- Liver function tests (periodic)
- Kidney function tests (periodic)
過量
Efficacy and toxicity are dependent on both the dose and the rate of administration. In dogs, the IV LD50 is 384 mg/kg when given over 12 hours, but drops to 48 mg/kg when infused IV over 120 hours. In the event of an inadvertent overdose, aggressive supportive therapy should be instituted.
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。