ゲムシタビン
ゲムシタビンは、抗悪性腫瘍薬として使用される**合成ピリミジンヌクレオシド類似体**です。 - **獣医療での用途**: 現在のところ臨床データが限られており、治験的治療と見なされています。切除不能な腫瘍に対する**放射線増感剤**として、または多剤併用化学療法（カルボプラチンとの併用など）の一部としての可能性が示されています。 - **ヒトでの用途**: 膵臓癌、小細胞肺癌、膀胱癌、軟部組織癌、およびリンパ腫の治療に有効性が認められています。 > **臨床のポイント**: 高価であり、重篤な骨髄抑制のリスクがあるため、獣医療での使用は通常、専門の腫瘍科に限定されます。
作用機序: 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.
動物種別の用量
- 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.
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
- Hypersensitivity to gemcitabine
- Known hypersensitivity to gemcitabine
- Pre-existing bone marrow suppression
有害事象
- 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)
薬物相互作用
- Other myelosuppressive agents · Additive toxic effects (myelosuppression, GI toxicity)
モニタリング
- 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)
過量投与
There is no known antidote to gemcitabine in an overdose situation. Severe myelosuppression should be expected. Treatment is supportive.
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。