Bendamustine is a type of DNA cross-linker that can lead to anti-helper function, alkylation, and DNA fragmentation. Bendamustine specifically affects the non-Hodgkin cell transplantation and DNA repair pathways. In SU-DHL-1 cells, bendamustine (50 μM) boosts p53 expression and promotes the NOXA and p21 (Cip1/Waf1) genes. Bendamustine (25 μM) disrupts mitotic checkpoints, leading to hyperplasia during mitosis [1]. Multiple myeloma (MM) cell lines such as RPMI-8226 and 8226-LR5 have lower cell viability when exposed to bendamustine; after 24 hours, the IC25 values of these lines are 101.8 μM and 585.5 μM, and after 48 hours, 51.7 and 374.3 μM, respectively. ..Bendamustine suppresses the spindle formation checkpoint and causes MM cell death triggered by caspase [2].

The DoHH-2, Granta 519, and RAMOS models showed 91%, 99%, and 95% inhibition of tumor cell proliferation in response to bendamustine (25 mg/kg, IV). Furthermore, rituximab improved the anticancer impact of bendamustine in the DoHH-2 and RAMOS models, but not in the Granta 519 model [3].

Absorption, Distribution and Excretion
Following a single IV dose of bendamustine hydrochloride Cmax typically occurred at the end of infusion. The dose proportionality of bendamustine has not been studied.
Mean recovery of total radioactivity in cancer patients following IV infusion of [14C] bendamustine hydrochloride was approximately 76% of the dose. Approximately 50% of the dose was recovered in the urine and approximately 25% of the dose was recovered in the feces. Urinary excretion was confirmed as a relatively minor pathway of elimination of bendamustine, with approximately 3.3% of the dose recovered in the urine as parent. Less than 1% of the dose was recovered in the urine as M3 and M4, and less than 5% of the dose was recovered in the urine as HP2.
The mean steady-state volume of distribution (Vss) of bendamustine was approximately 20-25 L. Steady-state volume of distribution for total radioactivity was approximately 50 L, indicating that neither bendamustine nor total radioactivity are extensively distributed into the tissues.
700 mL/min
... Preclinical radiolabeled bendamustine studies showed that approximately 90% of drug administered was recovered in excreta primarily in the feces. Bendamustine clearance in humans is approximately 700 mL/minute. After a single dose of 120 mg/sq m bendamustine IV over 1-hour the intermediate half life of the parent compound is approximately 40 minutes. The mean apparent terminal elimination half life of M3 and M4 are approximately 3 hours and 30 minutes respectively. Little or no accumulation in plasma is expected for bendamustine administered on Days 1 and 2 of a 28-day cycle.
In vitro, the binding of bendamustine to human serum plasma proteins ranged from 94-96% and was concentration independent from 1-50 ug/mL. Data suggest that bendamustine is not likely to displace or to be displaced by highly protein-bound drugs. The blood to plasma concentration ratios in human blood ranged from 0.84 to 0.86 over a concentration range of 10 to 100 ug/mL indicating that bendamustine distributes freely in human red blood cells. In humans, the mean steady state volume of distribution (Vss) was approximately 25 L.

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Metabolism / Metabolites
In vitro data indicate that bendamustine is primarily metabolized via hydrolysis to monohydroxy (HP1) and dihydroxy-bendamustine (HP2) metabolites with low cytotoxic activity. Two active minor metabolites, M3 and M4, are primarily formed via CYP1A2. However, concentrations of these metabolites in plasma are 1/10th and 1/100th that of the parent compound, respectively, suggesting that the cytotoxic activity is primarily due to bendamustine. Results of a human mass balance study confirm that bendamustine is extensively metabolized via hydrolytic, oxidative, and conjugative pathways.
... The detection of mercapturic acid pathway metabolites of bendamustine, namely, cysteine S-conjugates in human bile, which are supposed to subsequently undergo further metabolism /was recently reported/.. In this study, ... the identification and quantitation of consecutive bendamustine metabolites occurring in human bile using authentic reference standards and the synthesis and structural confirmation of these compounds /is described/. Mass spectrometry data along with high-performance liquid chromatography retention data (fluorescence detection) of the synthetic reference standards were consistent with those of the metabolites found in human bile after administration of bendamustine hydrochloride to cancer patients. Analysis of the purified synthetic reference compounds showed a purity of at least 95%. Structural confirmation was achieved by one- and two-dimensional proton as well as carbon-13 NMR spectroscopy and mass spectrometry. A total of 16 bendamustine-related compounds were detected in the bile of patients, 11 of them were recovered as conjugates. Eight conjugates have been structurally confirmed as novel mercapturic acids and sulfoxides. Biliary excretion of the sulfoxides was twice that of the mercapturate precursors. Glutathione S-conjugates of bendamustine have not been detected in bile samples, indicating rapid enzymatic cleavage in humans. Both the lack of glutathione (GSH) conjugates and occurrence of diastereomeric sulfoxides emphasize species-related differences in the GSH conjugation of bendamustine between humans and rats. The total amount recovered in the bile as the sum of all conjugates over the period of 24 hr after dosing averaged 5.2% of the administered dose.
In vitro data indicate that bendamustine is primarily metabolized via hydrolysis to metabolites with low cytotoxic activity. In vitro, studies indicate that two active minor metabolites, M3 and M4, are primarily formed via CYP1A2. However, concentrations of these metabolites in plasma are 1/10 and 1/100 that of the parent compound, respectively, suggesting that the cytotoxic activity is primarily due to bendamustine. In vitro studies using human liver microsomes indicate that bendamustine does not inhibit CYP1A2, 2C9/10, 2D6, 2E1, or 3A4/5. Bendamustine did not induce metabolism of CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2E1, or CYP3A4/5 enzymes in primary cultures of human hepatocytes.

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Biological Half-Life
40 minutes
After a single dose of 120 mg/sq m bendamustine IV over 1-hour the intermediate half life of the parent compound is approximately 40 minutes.

Hepatotoxicity
Mild and transient elevations in serum aminotransferase levels are found in up to 20% of patients treated with bendamustine, but elevations above 5 times the upper limit of normal occur in less than 3% of patients. The abnormalities are generally transient, unaccompanied by symptoms and rarely require dose modification. Clinically apparent liver injury from bendamustine has been limited to a small number of cases of mild hepatitis with features of hypersensitivity including eosinophilia, rash or other systemic symptoms. Autoantibody formation is uncommon. The course is generally self-limited, but may require corticosteroid therapy for control of symptoms and timely recovery.
Bendamustine therapy has also been implicated in causing reactivation of hepatitis B in patients with anti-HBc in serum with or without HBsAg. In several instances patients were also receiving corticosteroids or rituximab, yet had received these without reactivation in the past. Reactivation arose after 2 to 6 cycles of bendamustine chemotherapy, presenting with symptoms accompanied by HBsAg and rising levels of HBV DNA in serum. Reactivation was generally self-limited and patients later became HBsAg negative. In one instance, however, the course was severe and resulted in death from acute liver failure.
Likelihood score: C (probable cause of clinically apparent liver injury, some of which is due to reactivation of hepatitis B).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of bendamustine during breastfeeding. Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy, especially alkylating agents such as bendamustine. Based on the half-life of the drug and its metabolites, the drug should be eliminated from the milk by 24 to 48 hours after the last dose. The manufacturer recommends that breastfeeding be discontinued during bendamustine therapy and for at least 1 week after the last dose.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Some evidence indicates that the closely related drug carmustine can increase serum prolactin.

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Protein Binding
In vitro, the binding of bendamustine to human serum plasma proteins ranged from 94-96% and data suggest that bendamustine is not likely to displace or to be displaced by highly protein-bound drugs.

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Non-Human Toxicity Values
LD50 Rat oral 200-300 mg/kg /Bendamustine hydrochloride/[The Merck Index, Fourteenth Edition (2006)
LD50 Rat iv 40 mg/kg /Bendamustine hydrochloride/[The Merck Index, Fourteenth Edition (2006)
LD50 Mouse oral 400-500 mg/kg /Bendamustine hydrochloride/[The Merck Index, Fourteenth Edition (2006)
LD50 Mouse iv 80 mg/kg /Bendamustine hydrochloride/[The Merck Index, Fourteenth Edition (2006)

[1]. Bendamustine (Treanda) displays a distinct pattern of cytotoxicity and unique mechanistic features compared with other alkylating agents. Clin Cancer Res. 2008 Jan 1;14(1):309-17.

[2]. Bendamustine overcomes resistance to melphalan in myeloma cell lines by inducing cell death through mitotic catastrophe. Cell Signal. 2013 May;25(5):1108-17.

[3]. Navitoclax (ABT-263) and bendamustine ± rituximab induce enhanced killing of non-Hodgkin's lymphoma tumours in vivo. Br J Pharmacol. 2012 Oct;167(4):881-91.

Therapeutic Uses
Antineoplastic /Bendamustine hydrochloride/[The Merck Index, Fourteenth Edition (2006)
Bendamustine hydrochloride is used for the treatment of chronic lymphocytic leukemia (CLL) and is designated an orphan drug by the US Food and Drug Administration (FDA) for use in this condition. /Included in US product label/
Bendamustine administered as monotherapy is active in rituximab-refractory indolent non-Hodgkin's lymphoma, predominantly in patients with nontransformed or with sensitive disease characteristics. Therefore, bendamustine may be considered a reasonable choice for rituximab-refractory, indolent non-Hodgkin's lymphoma; bendamustine may also may be considered an alternative in patients who are not candidates for radioimmunotherapy due to either patient selection (i.e., a clinical contraindication) or accessibility issues. /Included in US product label/
Treanda for Injection is an alkylating drug indicated for treatment of patients with: Chronic lymphocytic leukemia (CLL). Efficacy relative to first line therapies other than chlorambucil has not been established. Indolent B-cell non-Hodgkin's lymphoma (NHL) that has progressed during or within six months of treatment with rituximab or a rituximab-containing regimen. /Included in US product label/
For more Therapeutic Uses (Complete) data for Bendamustine (8 total), please visit the HSDB record page.

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Drug Warnings
Infections, including pneumonia and sepsis, have been reported in patients receiving bendamustine and have been associated with hospitalization, septic shock, and death. Patients with myelosuppression have increased susceptibility to infection and should be advised to contact their clinician if signs or symptoms of infection occur.
In the phase 3 study in patients with chronic lymphocytic leukemia, grade 3 or 4 neutropenia occurred in 24% and febrile neutropenia occurred in 3% of patients receiving bendamustine; red blood cell or platelet transfusions were administered to 20 or less than 1%, respectively, of patients receiving the drug. Leukocytes, platelets, hemoglobin, and neutrophils should be monitored closely in patients with bendamustine-related myelosuppression. In the phase 3 study of bendamustine in chronic lymphocytic leukemia, hemoglobin concentrations and leukocyte and differential counts were monitored weekly and platelet counts were monitored each cycle. Data from this study indicate that blood counts may be expected to reach a nadir during the third week of the treatment cycle; dose delays may be required if recovery to recommended values has not occurred by day 28. Prior to initiation of the next cycle of therapy, the absolute neutrophil count (ANC) should be at least 1000/cu mm and the platelet count at least 75,000/ cu mm.
Tumor lysis syndrome has been reported in patients receiving bendamustine in clinical trials and during postmarketing surveillance. The onset generally occurs during the first cycle of bendamustine therapy; without appropriate intervention, acute renal failure and death may occur. Appropriate measures (e.g., adequate hydration; close monitoring of blood chemistries, particularly potassium and uric acid concentrations; use of allopurinol during the first 1-2 weeks of bendamustine therapy) should be used in patients at high risk for tumor lysis syndrome.
Infusion reactions, including fever, chills, pruritus, and rash, occur commonly in patients receiving bendamustine. Severe anaphylactic and anaphylactoid reactions have occurred rarely, mainly in the second and subsequent cycles of therapy. Patients should be monitored clinically, and bendamustine should be discontinued if a severe reaction occurs. Patients should be asked about symptoms suggestive of infusion reactions after their first cycle of therapy. A premedication regimen (e.g., antihistamine, antipyretic, and corticosteroid) should be considered during subsequent treatment cycles in patients who experience grade 1 or 2 infusion reactions. Discontinuance of bendamustine therapy should be considered in patients who experience grade 3 or 4 infusion reactions. Patients who experienced grade 3 or worse allergic-type reactions typically were not rechallenged with the drug in the phase 3 study of bendamustine in chronic lymphocytic leukemia.
For more Drug Warnings (Complete) data for Bendamustine (15 total), please visit the HSDB record page.

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Pharmacodynamics
No mean changes in QTc interval greater than 20 milliseconds were detected up to one hour post-infusion.

C16H21N3O2CL2

358.26284

357.101

16506-27-7

Bendamustine hydrochloride;3543-75-7;Bendamustine-d4;Bendamustine-d8;1134803-33-0

65628

White to off-white solid powder

2.9

1

4

9

23

380

0

CN1C2=C(C=C(C=C2)N(CCCl)CCCl)N=C1CCCC(=O)O

YTKUWDBFDASYHO-UHFFFAOYSA-N

InChI=1S/C16H21Cl2N3O2/c1-20-14-6-5-12(21(9-7-17)10-8-18)11-13(14)19-15(20)3-2-4-16(22)23/h5-6,11H,2-4,7-10H2,1H3,(H,22,23)

4-[5-[bis(2-chloroethyl)amino]-1-methylbenzimidazol-2-yl]butanoic acid

Bendamustine free base; SDX 105; SDX-105; SDX105; Bendamustina; DD6304600; Bendamustinum; Ribomustin. Brand name: Treanda;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~279.13 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.98 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.98 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.98 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)