吉西他濱
吉西他濱 (Gemcitabine) 是一種**合成的嘧啶核苷類似物**，作為抗腫瘤藥物使用。 - **獸醫用途**：目前被視為試驗性療法，臨床數據有限。它具有作為無法切除腫瘤的**放射增敏劑**的潛力，或作為聯合化療方案（例如與卡鉑合用）的一部分。 - **人類用途**：對治療胰腺癌、小細胞肺癌、膀胱癌、軟組織癌以及淋巴瘤具有療效。 > **臨床提示**：由於其成本高昂且具有顯著的骨髓抑制潛力，在獸醫學中的應用通常僅限於專業的腫瘤科門診。
作用機制: Gemcitabine is a **cell-cycle phase-specific** antimetabolite that acts primarily during the **S phase** (DNA synthesis) and blocks progression through the G1/S-phase boundary. - It is transported intracellularly and phosphorylated to **dFdCMP**, then to active diphosphate (**dFdCDP**) and triphosphate (**dFdCTP**) metabolites. - **dFdCDP** inhibits **ribonucleotide reductase**, depleting the cellular pool of deoxynucleotides required for DNA synthesis. - **dFdCTP** competes with endogenous deoxycytidine triphosphate (**dCTP**) for incorporation into the elongating DNA strand. Once incorporated, it causes **DNA chain termination** and subsequent apoptosis.
各物種劑量
- Carcinomas (in combination with carboplatin) · 2 mg/kg IV over 20-30 minutes · IV · no more than once every 7 days · Doses have ranged widely from 45 mg/m2-800 mg/m2 depending on the study.
- Exocrine pancreatic carcinoma (Low dose) · 20-25 mg/m2 or 2 mg/kg · IV · every 7 days · Administer as a 20 minute IV infusion.
- Carcinomas (in combination with carboplatin) · 2 mg/kg IV over 20-30 minutes · IV · no more than once every 7 days · Doses have ranged widely from 45 mg/m2-800 mg/m2 depending on the study.
- Bladder urothelial carcinoma, lymphoma, and various carcinomas (High dose) · 800-900 mg/m2 · IV · every 7-14 days · for 4 doses · Administer over 20-60 minutes.
- Bladder urothelial carcinoma, lymphoma, and various carcinomas (Low dose) · 25-50 mg/m2 · IV · once or twice a week · Administer over 20-60 minutes as per protocols.
- Carcinomas (Combination therapy) · 2 mg/kg · IV · every 7 days · Administer over 20-30 minutes (in 0.9% NaCl) combined with carboplatin.
- Advanced solid tumors · Escalating doses per protocol · IV · single administration or per protocol · Phase 1 dose-escalation trial.
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
- Hypersensitivity to gemcitabine
- Known hypersensitivity to gemcitabine
- Pre-existing bone marrow suppression
不良反應
- Myelosuppression (neutropenia and thrombocytopenia; nadir at 3-7 days)
- Mild to moderate gastrointestinal toxicity
- Retinal hemorrhage
- Myelosuppression (neutropenia, thrombocytopenia, anemia)
- Gastrointestinal toxicity (vomiting, diarrhea, anorexia)
- Retinal haemorrhage
- Treatment-related mortality (due to severe complications)
藥物相互作用
- Other myelosuppressive agents · Additive toxic effects (myelosuppression, GI toxicity)
監測
- CBC before each treatment
- Fundic exam weekly while on therapy
- Baseline renal and hepatic function prior to therapy, and periodically thereafter
- Complete Blood Count (CBC) prior to each dose (monitor for myelosuppression)
- Hepatic function panel
- Renal function panel
- Gastrointestinal signs (vomiting, diarrhea, anorexia)
- Ophthalmic exam (monitor for retinal haemorrhage)
過量
There is no known antidote to gemcitabine in an overdose situation. Severe myelosuppression should be expected. 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。