英文药名: Imuran(Azathioprine Tablets) 中文药名: 依木兰（硫唑嘌呤片） 生产厂家: Glaxo Smith Kline 药品名称 英文药名: Imuran (Azathioprine Tablets) 中文药名: 依木兰（硫唑嘌呤片） 别名：氮杂硫代嘌呤;咪唑巯嘌呤;依木兰;义美仁;硫唑嘌呤 外文名：Azathioprine,Imuran, AZP 生产厂家 (品牌)生产厂家: Glaxo Smith Kline 葛兰素史克 药理作用 本药是6-硫基嘌呤的咪唑衍生物，为具有免疫抑制作用的抗代谢剂。可产生烷基化作用阻断SH组群，抑制核酸的生物合成，防止细胞的增生，并可引起DNA的损害。动物实验证实，本药可使胸腺、脾内DNA、RNA减少，影响DNA、RNA，以及蛋白质的合成，主要抑制T-淋巴细胞而影响免疫，所以可抑制迟发过敏反应，器官移植的排斥反应。本药的疗效需于治疗数周或数月后才出现。在上消化道内吸收较佳。血浆中的硫唑嘌呤及6-硫基嘌呤水平与本药的疗效及毒性无相互关系。 毒理研究 本药可致染色体异常，动物实验表明可致不同程度的胎儿异常，并具有明显的致畸性，不能排除本药对人体的致癌性。 适应症 本药与其它药物联合应用于器官移植病人的抗排斥反应，例如肾移植、心脏移植及肝移植，亦减少肾移植受者对皮质激素的需求。本药也可单独使用于严重的风湿性关节炎，系统性红斑狼疮，皮肌炎/多发性肌炎，自体免疫性慢性活动性肝炎，寻常天疱疮，结节性多动脉炎，自体免疫性溶血性贫血，慢性顽固自发性血小板减少性紫癜。 用法用量 *注射剂只有在无法口服时才由静脉给药，且当口服疗法可以耐受时即应停用。 器官移植 第1日给予5 mg/kg体重，口服或静注。维持剂量要根据临床需要和血液系统的耐受性而调整，通常为1-4 mg/kg体重/日。维持治疗应无限期地进行。因为如果治疗中断，就有排斥的危险。 其它疾病 开始剂量为1-3 mg/kg体重/日。应根据临床反应和血液学指标所示耐受程度而定。治疗效果明显时，应减少维持量至可保持此治疗效果的最低水平。如3个月内病人情况无改善，应考虑停用。所需维持量从1 mg/kg体重/日至3 mg/kg体重/日不等，取决于临床治疗需要和病人个体反应，包括血液学指标所示的耐受程度。 兼有肝和/或肾功能不全者，剂量酌减。老年人用药的副作用发生率较其他病人高，应采用推荐剂量范围的低限值。 *本药片剂不应被切开。 任何疑问，请遵医嘱！ 不良反应 过敏反应：如全身不适、头晕、恶心、呕吐、腹泻、发热、寒战、肌痛、关节痛、肝功能异常和低血压。应立即停药和给予支持疗法，可使大部分病例恢复。 造血功能：可能产生剂量相关性、可逆性骨髓抑制，常见白细胞减少症，偶见贫血及血小板减少性紫癜。 感染：使用本药和肾上腺皮质激素的器官移植受者对病毒、真菌和细菌感染的易感性增加。 胃肠道反应：偶有恶心，餐后服药可缓解。罕见胰腺炎。 肺部反应：罕见可逆性肺炎。 禁忌症 对本药及6-疏基嘌呤过敏者禁用。 注意事项 在治疗的首8周内，至少每周检查1次全血象，包括血小板。如使用大剂量或病人有肝和/或肾功能不全时，血象检查的次数应该更多。此后每月或最少每3个月重复进行全血象的检查。 对肾和/或肝功能不全者，应使用推荐剂量的低限值及小心地监察血液学及肝肾功能。若出现肝或血液学毒性时，更应再减剂量。用药期间不要进行活疫苗的免疫接种。 孕妇及哺乳期妇女用药 临床上证明本药对胎儿有不良影响，只有对孕妇的益处大于对胎儿产生的危险时，才可考虑使用。本药可分泌入乳汁，故哺乳妇女慎用。 药物相互作用 别嘌呤醇可抑制巯基嘌呤（后者是硫唑嘌呤的活性代谢物）代谢成无活性产物，结果使巯基嘌呤的毒性增加，当二者必须同时服用时，硫唑嘌呤的剂量应该大大地减低，硫唑嘌呤可降低6-巯嘌呤的灭活率，6-巯嘌呤的灭活通过下列方式：酶的S-甲基化，与酶无关的氧化，或是被黄嘌呤氧化酶转变成硫尿酸盐等。硫唑嘌呤能与巯基化合物如谷胱甘肽起反应，在组织中缓缓释出6-巯嘌呤而起到前体药物的作用。 药物过量 症状 无法解释的感染、喉部溃疡、紫癜和出血，通常是用药9-14天达到最大的骨髓抑制而引起。一次性用药过量后，可出现恶心、呕吐及腹泻，接着是轻微的白血球减少和肝功能异常。 治疗 目前尚无特效解毒药，进行胃灌洗后，可予对症支持治疗及密切监察血象。  Imuran™ 依木蘭™ Azathioprine   Imuran™ Injection 50mg 1 vial Imuran™ Tablets 50mg 100's Imuran™ Tablets 25mg 100's IMURAN® (azathioprine) 50-mg Scored Tablets 100 mg (as the sodium salt) for I.V. injection, equivalent to 100 mg azathioprine sterile lyophilized material. PRODUCT INFORMATION Rx only WARNING Chronic immunosuppression with this purine antimetabolite increases risk of neoplasia in humans. Physicians using this drug should be very familiar with this risk as well as with the mutagenic potential to both men and women and with possible hematologic toxicities. See WARNINGS. DESCRIPTION IMURAN (azathioprine), an immunosuppressive antimetabolite, is available in tablet form for oral administration and 100-mg vials for intravenous injection. Each scored tablet contains 50 mg azathioprine and the inactive ingredients lactose, magnesium stearate, potato starch, povidone, and stearic acid. Each 100-mg vial contains azathioprine, as the sodium salt, equivalent to 100 mg azathioprine sterile lyophilized material and sodium hydroxide to adjust pH. Azathioprine is chemically 6-[(1-methyl-4-nitro-1H-imidazol-5-yl)thio]-1H-purine. The structural formula of azathioprine is: It is an imidazolyl derivative of 6-mercaptopurine and many of its biological effects are similar to those of the parent compound. Azathioprine is insoluble in water, but may be dissolved with addition of one molar equivalent of alkali. The sodium salt of azathioprine is sufficiently soluble to make a 10mg/mL water solution which is stable for 24 hours at 59° to 77°F (15° to 25°C). Azathioprine is stable in solution at neutral or acid pH but hydrolysis to mercaptopurine occurs in excess sodium hydroxide (0.1N), especially on warming. Conversion to mercaptopurine also occurs in the presence of sulfhydryl compounds such as cysteine, glutathione, and hydrogen sulfide. CLINICAL PHARMACOLOGY Azathioprine is well absorbed following oral administration. Maximum serum radioactivity occurs at 1 to 2 hours after oral 35S-azathioprine and decays with a half-life of 5 hours. This is not an estimate of the half-life of azathioprine itself, but is the decay rate for all 35S-containing metabolites of the drug. Because of extensive metabolism, only a fraction of the radioactivity is present as azathioprine. Usual doses produce blood levels of azathioprine, and of mercaptopurine derived from it, which are low (<1 mcg/mL). Blood levels are of little predictive value for therapy since the magnitude and duration of clinical effects correlate with thiopurine nucleotide levels in tissues rather than with plasma drug levels. Azathioprine and mercaptopurine are moderately bound to serum proteins (30%) and are partially dialyzable. See OVERDOSAGE. Azathioprine is metabolized to 6-mercaptopurine (6-MP). Both compounds are rapidly eliminated from blood and are oxidized or methylated in erythrocytes and liver; no azathioprine or mercaptopurine is detectable in urine after 8 hours. Activation of 6-mercaptopurine occurs via hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and a series of multi-enzymatic processes involving kinases to form 6-thioguanine nucleotides (6-TGNs) as major metabolites (See Metabolism Scheme in Figure 1). The cytotoxicity of azathioprine is due, in part, to the incorporation of 6-TGN into DNA. 6-MP undergoes two major inactivation routes (Figure 1). One is thiol methylation, which is catalyzed by the enzyme thiopurine S-methyltransferase (TPMT), to form the inactive metabolite methyl-6-MP (6-MeMP). TPMT activity is controlled by a genetic polymorphism.1, 2, 3 For Caucasians and African Americans, approximately 10% of the population inherit one non-functional TPMT allele (heterozygous) conferring intermediate TPMT activity, and 0.3% inherit two TPMT non-functional alleles (homozygous) for low or absent TPMT activity. Non-functional alleles are less common in Asians. TPMT activity correlates inversely with 6-TGN levels in erythrocytes and presumably other hematopoietic tissues, since these cells have negligible xanthine oxidase (involved in the other inactivation pathway) activities, leaving TPMT methylation as the only inactivation pathway. Patients with intermediate TPMT activity may be at increased risk of myelotoxicity if receiving conventional doses of IMURAN. Patients with low or absent TPMT activity are at an increased risk of developing severe, life-threatening myelotoxicity if receiving conventional doses of IMURAN.4-9 TPMT genotyping or phenotyping (red blood cell TPMT activity) can help identify patients who are at an increased risk for developing IMURAN toxicity.2, 3, 7, 8, 9 Accurate phenotyping (red blood cell TPMT activity) results are not possible in patients who have received recent blood transfusions. See WARNINGS, PRECAUTIONS: Drug Interactions, PRECAUTIONS: Laboratory Tests and ADVERSE REACTIONS sections. Figure 1. Metabolism pathway of azathioprine: competing pathways result in inactivation by TPMT or XO, or incorporation of cytotoxic nucleotides into DNA. GMPS: Guanosine monophosphate synthetase; HGPRT: Hypoxanthine-guanine-phosphoribosyl-transferase; IMPD: Inosine monophosphate dehydrogenase; MeMP: Methylmercaptopurine; MeMPN: Methylmercaptopurine nucleotide; TGN: Thioguanine nucleotides; TIMP: Thioinosine monophosphate; TPMT: Thiopurine S-methyltransferase; TU Thiouric acid; XO: Xanthine oxidase) (Adapted from Pharmacogenomics 2002; 3:89-98; and Cancer Res 2001; 61:5810-5816.) Another inactivation pathway is oxidation, which is catalyzed by xanthine oxidase (XO) to form 6-thiouric acid. The inhibition of xanthine oxidase in patients receiving allopurinol (ZYLOPRIM®) is the basis for the azathioprine dosage reduction required in these patients (see PRECAUTIONS: Drug Interactions). Proportions of metabolites are different in individual patients, and this presumably accounts for variable magnitude and duration of drug effects. Renal clearance is probably not important in predicting biological effectiveness or toxicities, although dose reduction is practiced in patients with poor renal function. INDICATIONS AND USAGE IMURAN is indicated as an adjunct for the prevention of rejection in renal homotransplantation. It is also indicated for the management of active rheumatoid arthritis to reduce signs and symptoms. CONTRAINDICATIONS IMURAN should not be given to patients who have shown hypersensitivity to the drug. IMURAN should not be used for treating rheumatoid arthritis in pregnant women. Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of neoplasia if treated with IMURAN. WARNINGS Severe leukopenia, thrombocytopenia, macrocytic anemia, and/or pancytopenia may occur in patients being treated with IMURAN. Severe bone marrow suppression may also occur. Patients with intermediate thiopurine S-methyl transferase (TPMT) activity may be at an increased risk of myelotoxicity if receiving conventional doses of IMURAN. Patients with low or absent TPMT activity are at an increased risk of developing severe, life-threatening myelotoxicity if receiving conventional doses of IMURAN. TPMT genotyping or phenotyping can help identify patients who are at an increased risk for developing IMURAN toxicity.2-9 (See PRECAUTIONS: Laboratory Tests). Hematologic toxicities are dose-related and may be more severe in renal transplant patients whose homograft is undergoing rejection. It is suggested that patients on IMURAN have complete blood counts, including platelet counts, weekly during the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage alterations or other therapy changes are necessary. Delayed hematologic suppression may occur. Prompt reduction in dosage or temporary withdrawal of the drug may be necessary if there is a rapid fall in or persistently low leukocyte count, or other evidence of bone marrow depression. Leukopenia does not correlate with therapeutic effect; therefore the dose should not be increased intentionally to lower the white blood cell count. Serious infections are a constant hazard for patients receiving chronic immunosuppression, especially for homograft recipients. Fungal, viral, bacterial, and protozoal infections may be fatal and should be treated vigorously. Reduction of azathioprine dosage and/or use of other drugs should be considered. IMURAN is mutagenic in animals and humans, carcinogenic in animals, and may increase the patient's risk of neoplasia. Renal transplant patients are known to have an increased risk of malignancy, predominantly skin cancer and reticulum cell or lymphomatous tumors. The risk of post-transplant lymphomas may be increased in patients who receive aggressive treatment with immunosuppressive drugs. The degree of immunosuppression is determined, not only by the immunosuppressive regimen, but also by a number of other patient factors. The number of immunosuppressive agents may not necessarily increase the risk of post-transplant lymphomas. However, transplant patients who receive multiple immunosuppressive agents may be at risk for over-immunosuppression; therefore, immunosuppressive drug therapy should be maintained at the lowest effective levels. Information is available on the spontaneous neoplasia risk in rheumatoid arthritis, and on neoplasia following immunosuppressive therapy of other autoimmune diseases. It has not been possible to define the precise risk of neoplasia due to IMURAN. The data suggest the risk may be elevated in patients with rheumatoid arthritis, though lower than for renal transplant patients. However, acute myelogenous leukemia as well as solid tumors have been reported in patients with rheumatoid arthritis who have received azathioprine. Data on neoplasia in patients receiving IMURAN can be found under ADVERSE REACTIONS. IMURAN has been reported to cause temporary depression in spermatogenesis and reduction in sperm viability and sperm count in mice at doses 10 times the human therapeutic dose;10 a reduced percentage of fertile matings occurred when animals received 5 mg/kg. 11 PRECAUTIONS ADVERSE REACTIONS The principal and potentially serious toxic effects of IMURAN are hematologic and gastrointestinal. The risks of secondary infection and neoplasia are also significant (see WARNINGS). The frequency and severity of adverse reactions depend on the dose and duration of IMURAN as well as on the patient's underlying disease or concomitant therapies. The incidence of hematologic toxicities and neoplasia encountered in groups of renal homograft recipients is significantly higher than that in studies employing IMURAN for rheumatoid arthritis. The relative incidences in clinical studies are summarized below: Toxicity Renal Homograft Rheumatoid Arthritis Leukopenia (any degree) >50% 28% <2500 cells/mm3 16% 5.3% Infections 20% <1% Neoplasia *    Lymphoma 0.5%    Others 2.8% * Data on the rate and risk of neoplasia among persons with rheumatoid arthritis treated with azathioprine are limited. The incidence of lymphoproliferative disease in patients with RA appears to be significantly higher than that in the general population. In one completed study, the rate of lymphoproliferative disease in RA patients receiving higher than recommended doses of azathioprine (5 mg/kg per day) was 1.8 cases per 1000 patient-years of follow-up, compared with 0.8 cases per 1000 patient-years of follow-up in those not receiving azathioprine. However, the proportion of the increased risk attributable to the azathioprine dosage or to other therapies (i.e., alkylating agents) received by patients treated with azathioprine cannot be determined. OVERDOSAGE The oral LD50s for single doses of IMURAN in mice and rats are 2500 mg/kg and 400 mg/kg, respectively. Very large doses of this antimetabolite may lead to marrow hypoplasia, bleeding, infection, and death. About 30% of IMURAN is bound to serum proteins, but approximately 45% is removed during an 8-hour hemodialysis.24 A single case has been reported of a renal transplant patient who ingested a single dose of 7500 mg IMURAN. The immediate toxic reactions were nausea, vomiting, and diarrhea, followed by mild leukopenia and mild abnormalities in liver function. The white blood cell count, SGOT, and bilirubin returned to normal 6 days after the overdose. DOSAGE AND ADMINISTRATION HOW SUPPLIED 50 mg overlapping circle-shaped, yellow to off-white, scored tablets imprinted with “IMURAN” and “50” on each tablet; bottle of 100 (NDC 65483-590-10). Store at 15° to 25°C (59° to 77°F) in a dry place and protect from light. 20-mL vial, each containing the equivalent of 100 mg azathioprine (as the sodium salt) (NDC 65483-551-01). Store at 15° to 25°C (59° to 77°F) and protect from light. The sterile, lyophilized sodium salt is yellow, and should be dissolved in Sterile Water for Injection