羥基脲 (Hydroxycarbamide / Hydroxyurea)
抗腫瘤藥 - 抗代謝物
羥基脲是一種抗代謝的抗腫瘤藥物，主要用於獸醫學中治療骨髓增生性疾病（如真性紅血球增多症和白血病），以及肥大細胞瘤和犬腦膜瘤的輔助治療。 > **警告**：本品為細胞毒性藥物，必須嚴格遵守安全操作規範以防止人員暴露。 **臨床提示**：貓對羥基脲的骨髓抑制作用更為敏感，初期需要更密集的監測。
作用機制: Hydroxycarbamide inhibits the enzyme **ribonucleotide reductase** → prevents the conversion of ribonucleotides to deoxyribonucleotides → depletes the intracellular pool of precursors essential for **DNA synthesis and repair**. It is a cell-cycle specific agent acting primarily in the **S-phase**, but it may also arrest cells at the G1-S border.
各物種劑量
Dogs
- Polycythaemia vera, chronic myeloid leukaemia, mast cell tumours, meningiomas · See Appendix for chemotherapy protocols · PO · variable · Reduce dosage frequency once in remission · Perform haematology initially weekly for one month, then every two weeks for one month, then monthly if tolerated.
Cats
- Polycythaemia vera, chronic myeloid leukaemia · See Appendix for chemotherapy protocols · PO · variable · Reduce dosage frequency once in remission · Haematology MUST be monitored weekly at the start of drug therapy due to greater risk of myelosuppression.
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
PO
禁忌症
- Pre-existing bone marrow suppression
不良反應
- Myelosuppression (dose-limiting)
- Nausea
- Vomiting
- Diarrhoea
- Anorexia
- Dysuria
- Stomatitis
- Sloughing of nails
- Alopecia
- Methaemoglobinaemia (in cats at high doses)
- Cardiovascular changes (increased diastolic BP/HR, decreased systolic BP)
藥物相互作用
- Other myelosuppressive agents · Increased risk of severe bone marrow suppression · major
監測
- Haematology (weekly for 1 month, then biweekly for 1 month, then monthly)
- Renal function parameters
- Blood pressure and ECG (due to potential cardiovascular effects)
過量
In cats, very high doses (>500 mg) have been reported to cause **methaemoglobinaemia**.
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。