地西他滨
生产厂家：美国强生公司(Johnson & Johnson）
功能主治：可用于晚期骨髓增生性肿瘤，联合疗法中位生存21个月
用法用量：用法用量 本品不同剂型、不同规格的用法用量可能存在差异，请阅读具体药物说明书使用，或遵医嘱。 注射用地西他滨：治疗期间须进行全血和血小板计数以监测临床反应和毒性，保证在每个给药周期前至少达到最低限。 在开始治疗前还应检测肝脏生化和血清肌酐。 推荐两种给药方案：给药方案一(3天给药方案)1、地西他滨给药剂量为15mg/m2，连续静脉输注3小时以上，每8小时一次，连续3天。 患者可预先使用常规止吐药。 2、给药周期每6周重复一个周期。 推荐至少重复4个周期。 然而，获得完全缓解或部分缓解的患者可以治疗4个周期以上。 如果患者能继续获益可以持续用药。 3、依据血液学实验室检查值进行的剂量调整或延迟给药如果经过前一个周期的地西他滨治疗，血液学恢复(中性粒细胞绝对计数[ANC]≥1000/μL，血小板≥50000/μL)需要超过6周，则下一周期的治疗应延迟，且剂量应按以下原则进行暂时性的调整：(1)恢复时间超过6周，但少于8周-给药应延迟2周，且重新开始治疗剂量减少到11mg/m2，每8小时一次，(33mg/m2/天，99mg/m2/周期); (2)恢复时间超过8周，但少于10周-患者应进行疾病进展的评估(通过骨髓穿刺评估)，如未出现进展，给药应延迟2周以上，重新开始时剂量应减少到11mg/m2，每8小时一次(33mg/m2/天，99mg/m2/周期)，然后在接下来的周期中，根据临床情况维持或增加剂量。 4、依据非血液学毒性进行的剂量调整或延迟给药：在第一个地西他滨治疗周期后，如果出现以下非血液学毒性，暂停地西他滨用药直至毒性消失：①血清肌酐≥2mg/dL; ②丙氨酸氨基转移酶(ALT)、总胆红素≥2倍正常值最高上限(ULN); ③活动性或未控制的感染。 给药方案二(5天给药方案)1、地西他滨的给药剂量为20mg/m2，连续静脉输注1小时，每天一次，连续5天。 每4周重复一个周期。 患者可预先使用常规止吐药。 2、如果出现骨髓抑制，后续治疗周期应推迟至血液学指标恢复(ANC≥1,000/μL，血小板≥50,000/μL)。 如果出现非血液学毒性亦应参照方案一处理。 3、基于国外临床研究数据提示与3天给药方案相比，5天给药方案具有更好的耐受性。 该方案已经在国外获得批准。 中国人群应用经验有限。 请主治医生根据中国患者自身状况选择合理给药方案。 4、静脉给药操作：(1)地西他滨是细胞毒性药物，操作和配制地西他滨时应当小心。 应当采用恰当的处理和处置抗肿瘤药物的手段。 (2)本品应当在无菌条件下用注射用水复溶(10mg规格用2ml注射用水复溶; 50mg规格用10ml注射用水复溶)：配制成每毫升约含5.0mg地西他滨，pH6.7-7.3的溶液。 复溶后，立即再用0.9%NaCl注射液、5%葡萄糖注射液或乳酸林格氏液进一步稀释成终溶度为0.1-1.0mg/mL的溶液。 建议即配即用。 如复溶后15分钟未能使用，稀释液必须用2-8℃的冷输液配制，并在2-8℃(360F-460F)保存，最多不超过7小时。 (3)只要溶液和容器允许，非口服给药的药品在给药前应检查可见异物和颜色。 当出现可见异物或颜色变化，请勿使用。
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Decitabine, also known as 5-aza-2'-deoxycytidine, is a DNA methyltransferase inhibitor that has been approved by the US Food and Drug Administration (FDA) for the treatment of various blood disorders. This article will discuss the mechanism of action, clinical applications, and potential side effects of decitabine.
Mechanism of ActionThe mechanism of action of decitabine is based on its ability to inhibit DNA methyltransferase, thus leading to the demethylation of DNA. DNA methylation is a process by which methyl groups are added to the DNA molecule, which can lead to the silencing of genes involved in various cellular processes, including cell differentiation and proliferation. By inhibiting DNA methylation, decitabine can reactivate genes that are involved in tumor suppression and induce differentiation of cancer cells.
Clinical Applications
Decitabine has been approved by the FDA for the treatment of myelodysplastic syndromes (MDS), which are a group of blood disorders characterized by abnormal production of blood cells in the bone marrow. MDS can progress to acute myeloid leukemia (AML), a more aggressive form of blood cancer if left untreated. Decitabine has been shown to improve the survival of patients with MDS and has been recommended by the National Comprehensive Cancer Network guidelines as a first-line treatment for high-risk MDS.
In addition to MDS, decitabine has also shown promising results in the treatment of other hematologic malignancies, including AML and chronic myelomonocytic leukemia (CMML). Decitabine has also been studied in the treatment of solid tumors, including lung and breast cancer, with mixed results.
Potential Side Effects
Decitabine is generally well-tolerated, with mild to moderate side effects reported in clinical trials. The most common side effects include nausea, vomiting, fatigue, and low blood cell counts. In rare cases, patients may develop serious complications, such as bleeding or infections.
Conclusion
Decitabine is a promising treatment for blood disorders, particularly MDS, and has shown potential in the treatment of other hematologic malignancies and solid tumors. Its mechanism of action, which involves the reactivation of tumor suppressor genes and induction of cell differentiation, holds great promise for the development of new cancer therapies. However, further studies are needed to determine the optimal dosing and duration of treatment and to identify patients who are most likely to benefit from decitabine therapy.
