英文药名: Leukeran(Chlorambucil)

中文药名: 留可然（苯丁酸氮芥）

药品名称
通用名称：苯丁酸氮芥片
商品名称：留可然
英文名称：Chlorambucil　Tablets
汉语拼音：Bendingsuandanjie Pian
药理作用
本品属氮芥类衍生物，具有双功能烷化剂作用，可形成不稳定的乙撑亚胺而发挥其细胞毒作用，干扰 DNA 和 RNA 的功能。在常规剂量下，其毒性较其他任何氮芥类药物小。对增殖状态的细胞敏感，特别对G1期与M期的作用最强，属细胞周期非特异性药物。对淋巴细胞有一定的选择性控制作用。
药代动力学
口服吸收完全，生物利用度大于70% ，在1小时内，肝脏可达最高的组织浓度。其代谢产物苯乙酸氮芥于用药后2～4小时在血浆中达峰值，其血浆浓度与原形相当，半衰期1～2小时，药时曲线下面积大，具有双功能烷化剂作用。 24小时内60% 的药物随尿排出，其中90% 为苯丁酸氮芥和苯乙酸氮芥的水解物。部分的药物分子有亲脂肪特性而储存于脂肪中，从而延长本品的临床作用时间。
适应症
霍奇金病，数种非霍奇金病淋巴瘤，慢性淋巴细胞性白血病，瓦尔登斯特伦巨球蛋白血症，晚期卵巢腺癌。本品对于部分乳腺癌病人也有明显的疗效。
用法用量
每日0.1～0.2mg/kg(6～10mg) 或（4～8mg/m2 ），每日1次或分3～4次口服，连用 3 ～ 6 周， 1 疗程总量可达 300 ～ 500mg 。
不良反应
骨髓抑制：属中等程度，主要表现为白细胞减少，对血小板影响较轻，但大剂量连续用药时可出现全血象下降。
胃肠道反应：较轻，多为食欲减退、恶心，偶见呕吐。
生殖系统反应：长期应用本品可致精子缺乏或持久不育，月经紊乱或停经。
其他少见的不良反应尚包括中枢神经系统毒性、皮疹、脱发、肝损害及发热等，长期或高剂量应用可导致间质性肺炎。
禁忌
凡有严重骨髓抑制、感染者禁用，有痛风病史、泌尿道结石者慎用。对本品过敏者禁用。
注意事项
本品给药时间较长，疗效及毒性多在治疗3周以后出现，故应密切观察血相变化，并注意蓄积毒性。

Leukeran
Generic Name: chlorambucil
Dosage Form: tablet, film coated
Leukeran®
(chlorambucil)
Tablets
Leukeran Description
Leukeran (chlorambucil) was first synthesized by Everett et al. It is a bifunctional alkylating agent of the nitrogen mustard type that has been found active against selected human neoplastic diseases. Chlorambucil is known chemically as 4-[bis(2-chlorethyl)amino]benzenebutanoic acid and has the following structural formula:
Chlorambucil hydrolyzes in water and has a pKa of 5.8.
Leukeran (chlorambucil) is available in tablet form for oral administration. Each film-coated tablet contains 2 mg chlorambucil and the inactive ingredients colloidal silicon dioxide, hypromellose, lactose (anhydrous), macrogol/PEG 400, microcrystalline cellulose, red iron oxide, stearic acid, titanium dioxide, and yellow iron oxide.
Leukeran - Clinical Pharmacology
Mechanism of Action
Chlorambucil, an aromatic nitrogen mustard derivative, is an alkylating agent. Chlorambucil interferes with DNA replication and induces cellular apoptosis via the accumulation of cytosolic p53 and subsequent activation of Bax, an apoptosis promoter.
Pharmacokinetics
In a study of 12 patients given single oral doses of 0.2 mg/kg of Leukeran, the mean dose-adjusted (±SD) plasma chlorambucil Cmax was 492 ± 160 ng/mL, the AUC was 883 ± 329 ng.h/mL, the mean elimination half-life (t½) was 1.3 ± 0.5 hours, and the Tmax was 0.83 ± 0.53 hours. For the major metabolite, phenylacetic acid mustard (PAAM), the mean dose-adjusted (± SD) plasma Cmax was 306 ± 73 ng/mL, the AUC was 1204 ± 285 ng.h/mL, mean t½ was 1.8 ± 0.4 hours, and the Tmax was 1.9 ± 0.7 hours.
After single oral doses of 0.6 to 1.2 mg/kg, peak plasma chlorambucil levels (Cmax) are reached within 1 hour and the terminal elimination half-life (t½) of the parent drug is estimated at 1.5 hours.
Absorption: Chlorambucil is rapidly and completely (>70%) absorbed from the gastrointestinal tract. Consistent with the rapid, predictable absorption of chlorambucil, the inter-individual variability in the plasma pharmacokinetics of chlorambucil has been shown to be relatively small following oral dosages of between 15 and 70 mg (2-fold intra-patient variability, and a 2 to 4 fold interpatient variability in AUC). The absorption of chlorambucil is reduced when taken after food. In a study of ten patients, food intake increased the median Tmax by 2-fold and reduced the dose-adjusted Cmax and AUC values by 55% and 20%, respectively.
Distribution: The apparent volume of distribution averaged 0.31 L/kg following a single 0.2 mg/kg oral dose of chlorambucil in 11 cancer patients with chronic lymphocytic leukemia.
Chlorambucil and its metabolites are extensively bound to plasma and tissue proteins. In vitro, chlorambucil is 99% bound to plasma proteins, specifically albumin. Cerebrospinal fluid levels of chlorambucil have not been determined.
Metabolism: Chlorambucil is extensively metabolized in the liver primarily to phenylacetic acid mustard, which has antineoplastic activity. Chlorambucil and its major metabolite undergo oxidative degradation to monohydroxy and dihydroxy derivatives.
Excretion: After a single dose of radiolabeled chlorambucil (14C), approximately 20% to 60% of the radioactivity appears in the urine after 24 hours. Again, less than 1% of the urinary radioactivity is in the form of chlorambucil or phenylacetic acid mustard.
Indications and Usage for Leukeran
Leukeran (chlorambucil) is indicated in the treatment of chronic lymphatic (lymphocytic) leukemia, malignant lymphomas including lymphosarcoma, giant follicular lymphoma, and Hodgkin’s disease. It is not curative in any of these disorders but may produce clinically useful palliation.
Contraindications
Chlorambucil should not be used in patients whose disease has demonstrated a prior resistance to the agent. Patients who have demonstrated hypersensitivity to chlorambucil should not be given the drug. There may be cross-hypersensitivity (skin rash) between chlorambucil and other alkylating agents.
Warnings
Because of its carcinogenic properties, chlorambucil should not be given to patients with conditions other than chronic lymphatic leukemia or malignant lymphomas. Convulsions, infertility, leukemia, and secondary malignancies have been observed when chlorambucil was employed in the therapy of malignant and non-malignant diseases.
There are many reports of acute leukemia arising in patients with both malignant and non-malignant diseases following chlorambucil treatment. In many instances, these patients also received other chemotherapeutic agents or some form of radiation therapy. The quantitation of the risk of chlorambucil-induction of leukemia or carcinoma in humans is not possible. Evaluation of published reports of leukemia developing in patients who have received chlorambucil (and other alkylating agents) suggests that the risk of leukemogenesis increases with both chronicity of treatment and large cumulative doses. However, it has proved impossible to define a cumulative dose below which there is no risk of the induction of secondary malignancy. The potential benefits from chlorambucil therapy must be weighed on an individual basis against the possible risk of the induction of a secondary malignancy.
Chlorambucil has been shown to cause chromatid or chromosome damage in humans. Both reversible and permanent sterility have been observed in both sexes receiving chlorambucil.
A high incidence of sterility has been documented when chlorambucil is administered to prepubertal and pubertal males. Prolonged or permanent azoospermia has also been observed in adult males. While most reports of gonadal dysfunction secondary to chlorambucil have related to males, the induction of amenorrhea in females with alkylating agents is well documented and chlorambucil is capable of producing amenorrhea. Autopsy studies of the ovaries from women with malignant lymphoma treated with combination chemotherapy including chlorambucil have shown varying degrees of fibrosis, vasculitis, and depletion of primordial follicles.
Rare instances of skin rash progressing to erythema multiforme, toxic epidermal necrolysis, or Stevens-Johnson syndrome have been reported. Chlorambucil should be discontinued promptly in patients who develop skin reactions.
Pregnancy
Pregnancy Category D. Chlorambucil can cause fetal harm when administered to a pregnant woman. Unilateral renal agenesis has been observed in 2 offspring whose mothers received chlorambucil during the first trimester. Urogenital malformations, including absence of a kidney, were found in fetuses of rats given chlorambucil. There are no adequate and well-controlled studies in pregnant women. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should be advised to avoid becoming pregnant.
Precautions
General
Many patients develop a slowly progressive lymphopenia during treatment. The lymphocyte count usually rapidly returns to normal levels upon completion of drug therapy. Most patients have some neutropenia after the third week of treatment and this may continue for up to 10 days after the last dose. Subsequently, the neutrophil count usually rapidly returns to normal. Severe neutropenia appears to be related to dosage and usually occurs only in patients who have received a total dosage of 6.5 mg/kg or more in one course of therapy with continuous dosing. About one quarter of all patients receiving the continuous-dose schedule, and one third of those receiving this dosage in 8 weeks or less may be expected to develop severe neutropenia.
While it is not necessary to discontinue chlorambucil at the first evidence of a fall in neutrophil count, it must be remembered that the fall may continue for 10 days after the last dose, and that as the total dose approaches 6.5 mg/kg, there is a risk of causing irreversible bone marrow damage. The dose of chlorambucil should be decreased if leukocyte or platelet counts fall below normal values and should be discontinued for more severe depression.
Chlorambucil should not be given at full dosages before 4 weeks after a full course of radiation therapy or chemotherapy because of the vulnerability of the bone marrow to damage under these conditions. If the pretherapy leukocyte or platelet counts are depressed from bone marrow disease process prior to institution of therapy, the treatment should be instituted at a reduced dosage.
Persistently low neutrophil and platelet counts or peripheral lymphocytosis suggest bone marrow infiltration. If confirmed by bone marrow examination, the daily dosage of chlorambucil should not exceed 0.1 mg/kg. Chlorambucil appears to be relatively free from gastrointestinal side effects or other evidence of toxicity apart from the bone marrow depressant action. In humans, single oral doses of 20 mg or more may produce nausea and vomiting.
Children with nephrotic syndrome and patients receiving high pulse doses of chlorambucil may have an increased risk of seizures. As with any potentially epileptogenic drug, caution should be exercised when administering chlorambucil to patients with a history of seizure disorder or head trauma, or who are receiving other potentially epileptogenic drugs.
Administration of live vaccines to immunocompromised patients should be avoided.
Information for Patients
Patients should be informed that the major toxicities of chlorambucil are related to hypersensitivity, drug fever, myelosuppression, hepatotoxicity, infertility, seizures, gastrointestinal toxicity, and secondary malignancies. Patients should never be allowed to take the drug without medical supervision and should consult their physician if they experience skin rash, bleeding, fever, jaundice, persistent cough, seizures, nausea, vomiting, amenorrhea, or unusual lumps/masses. Women of childbearing potential should be advised to avoid becoming pregnant.
Laboratory Tests
Patients must be followed carefully to avoid life-endangering damage to the bone marrow during treatment. Weekly examination of the blood should be made to determine hemoglobin levels, total and differential leukocyte counts, and quantitative platelet counts. Also, during the first 3 to 6 weeks of therapy, it is recommended that white blood cell counts be made 3 or 4 days after each of the weekly complete blood counts. Galton et al have suggested that in following patients it is helpful to plot the blood counts on a chart at the same time that body weight, temperature, spleen size, etc., are recorded. It is considered dangerous to allow a patient to go more than 2 weeks without hematological and clinical examination during treatment.
Drug Interactions
There are no known drug/drug interactions with chlorambucil.
Carcinogenesis, Mutagenesis, Impairment of Fertility
See WARNINGS section for information on carcinogenesis, mutagenesis, and impairment of fertility.
Pregnancy
Teratogenic Effects: Pregnancy Category D: See WARNINGS section.
Nursing Mothers
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from chlorambucil, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric Use
The safety and effectiveness in pediatric patients have not been established.
Geriatric Use
Clinical studies of chlorambucil did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Use in Patients with Renal Impairment: The impact of renal impairment on chlorambucil elimination has not been formally studied. The renal elimination of unchanged chlorambucil and its major active metabolites, phenylacetic acid mustard, represents less than 1% of the administered dose. In addition, no dose adjustment was required in 2 dialysis patients on chlorambucil. Therefore, renal impairment is not expected to significantly impact the elimination of chlorambucil.
Use in Patients with Hepatic Impairment: No formal studies have been conducted in patients with hepatic impairment. As chlorambucil is primarily metabolized in the liver, patients with hepatic impairment should be closely monitored for toxicity and dose reduction may be considered in patients with hepatic impairment when treated with Leukeran (see DOSAGE AND ADMINISTRATION).
Adverse Reactions
To report SUSPECTED ADVERSE REACTIONS, contact Aspen Global Inc. Toll-Free at 1-855-800-8165 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Hematologic
The most common side effect is bone marrow suppression, anemia, leukopenia, neutropenia, thrombocytopenia, or pancytopenia. Although bone marrow suppression frequently occurs, it is usually reversible if the chlorambucil is withdrawn early enough. However, irreversible bone marrow failure has been reported.
Gastrointestinal
Gastrointestinal disturbances such as nausea and vomiting, diarrhea, and oral ulceration occur infrequently.
CNS
Tremors, muscular twitching, myoclonia, confusion, agitation, ataxia, flaccid paresis, and hallucinations have been reported as rare adverse experiences to chlorambucil which resolve upon discontinuation of drug. Rare, focal and/or generalized seizures have been reported to occur in both children and adults at both therapeutic daily doses and pulse-dosing regimens, and in acute overdose (see PRECAUTIONS: General).
Dermatologic
Allergic reactions such as urticaria and angioneurotic edema have been reported following initial or subsequent dosing. Skin hypersensitivity (including rare reports of skin rash progressing to erythema multiforme, toxic epidermal necrolysis, and Stevens-Johnson syndrome) has been reported (see WARNINGS).
Miscellaneous
Other reported adverse reactions include: pulmonary fibrosis, hepatotoxicity and jaundice, drug fever, peripheral neuropathy, interstitial pneumonia, sterile cystitis, infertility, leukemia, and secondary malignancies (see WARNINGS).
Overdosage
Reversible pancytopenia was the main finding of inadvertent overdoses of chlorambucil. Neurological toxicity ranging from agitated behavior and ataxia to multiple grand mal seizures has also occurred. As there is no known antidote, the blood picture should be closely monitored and general supportive measures should be instituted, together with appropriate blood transfusions, if necessary. Chlorambucil is not dialyzable.
Oral LD50 single doses in mice are 123 mg/kg. In rats, a single intraperitoneal dose of 12.5 mg/kg of chlorambucil produces typical nitrogen-mustard effects; these include atrophy of the intestinal mucous membrane and lymphoid tissues, severe lymphopenia becoming maximal in 4 days, anemia, and thrombocytopenia. After this dose, the animals begin to recover within 3 days and appear normal in about a week, although the bone marrow may not become completely normal for about 3 weeks. An intraperitoneal dose of 18.5 mg/kg kills about 50% of the rats with development of convulsions. As much as 50 mg/kg has been given orally to rats as a single dose, with recovery. Such a dose causes bradycardia, excessive salivation, hematuria, convulsions, and respiratory dysfunction.
Leukeran Dosage and Administration
The usual oral dosage is 0.1 to 0.2 mg/kg body weight daily for 3 to 6 weeks as required. This usually amounts to 4 to 10 mg per day for the average patient. The entire daily dose may be given at one time. These dosages are for initiation of therapy or for short courses of treatment. The dosage must be carefully adjusted according to the response of the patient and must be reduced as soon as there is an abrupt fall in the white blood cell count. Patients with Hodgkin’s disease usually require 0.2 mg/kg daily, whereas patients with other lymphomas or chronic lymphocytic leukemia usually require only 0.1 mg/kg daily. When lymphocytic infiltration of the bone marrow is present, or when the bone marrow is hypoplastic, the daily dose should not exceed 0.1 mg/kg (about 6 mg for the average patient).
Alternate schedules for the treatment of chronic lymphocytic leukemia employing intermittent, biweekly, or once-monthly pulse doses of chlorambucil have been reported. Intermittent schedules of chlorambucil begin with an initial single dose of 0.4 mg/kg. Doses are generally increased by 0.1 mg/kg until control of lymphocytosis or toxicity is observed. Subsequent doses are modified to produce mild hematologic toxicity. It is felt that the response rate of chronic lymphocytic leukemia to the biweekly or once-monthly schedule of chlorambucil administration is similar or better to that previously reported with daily administration and that hematologic toxicity was less than or equal to that encountered in studies using daily chlorambucil.
Radiation and cytotoxic drugs render the bone marrow more vulnerable to damage, and chlorambucil should be used with particular caution within 4 weeks of a full course of radiation therapy or chemotherapy. However, small doses of palliative radiation over isolated foci remote from the bone marrow will not usually depress the neutrophil and platelet count. In these cases chlorambucil may be given in the customary dosage.
It is presently felt that short courses of treatment are safer than continuous maintenance therapy, although both methods have been effective. It must be recognized that continuous therapy may give the appearance of “maintenance” in patients who are actually in remission and have no immediate need for further drug. If maintenance dosage is used, it should not exceed 0.1 mg/kg daily and may well be as low as 0.03 mg/kg daily. A typical maintenance dose is 2 mg to 4 mg daily, or less, depending on the status of the blood counts. It may, therefore, be desirable to withdraw the drug after maximal control has been achieved, since intermittent therapy reinstituted at time of relapse may be as effective as continuous treatment.
Procedures for proper handling and disposal of anticancer drugs should be used. Several guidelines on this subject have been published.1-4 There is no general agreement that all of the procedures recommended in the guidelines are necessary or appropriate.
Special Populations
Hepatic Impairment: Patients with hepatic impairment should be closely monitored for toxicity. As chlorambucil is primarily metabolized in the liver, dose reduction may be considered in patients with hepatic impairment when treated with Leukeran. However, there are insufficient data in patients with hepatic impairment to provide a specific dosing recommendation.
How is Leukeran Supplied
Leukeran is supplied as brown, film-coated, round, biconvex tablets containing 2 mg chlorambucil in amber glass bottles with child-resistant closures. One side is engraved with “GX EG3” and the other side is engraved with an “L.”
Bottle of 50 (NDC 76388-635-50).
Store in a refrigerator, 2° to 8°C (36° to 46°F).

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