当单独使用 MTX 时，异常细胞 (Abs) 和微核双核细胞 (MNBN) 的百分比呈浓度依赖性增加。核分裂指数 (NDI) 随着 MTX 浓度的升高而下降。同样，在检测的每个 MTX 浓度下，有丝分裂指数 (MI) 也同样下降。添加 50 μg/mL 的亚叶酸可显着降低 MNBN (40-68%) 和 Abs (36-77%) 的百分比。此外，在 5 μg/mL 亚叶酸下，观察到抑制作用（MNBN 为 12% 至 54%，Abs 为 20% 至 61%）[1]。

接受甲氨蝶呤 (MTX) 三周后，用甲酰四氢叶酸（7.0 mg/kg；腹腔注射；每隔一天；对于 Balb/c 幼年雄性小鼠）治疗似乎可以抵消这种生长抑制（长期给药时，MTX 会减少小鼠的骨骼生长） [2]。

Animal/Disease Models: 24 Balb/c young growing male mice aged 3 weeks (11.88 ± 0.25 g)[2]
Doses: 7.0 mg/kg
Route of Administration: intraperitoneal (ip)injection; every second day; for 3 weeks
Experimental Results: Following methotrexate (MTX) administration appears to reverse this growth inhibition.

Absorption, Distribution and Excretion
Following oral administration, leucovorin is rapidly absorbed. The apparent bioavailability of leucovorin was 97% for 25 mg, 75% for 50 mg, and 37% for 100 mg.
Duration of action: All routes: 3 to 6 hours.
Onset of action: Oral: 20 to 30 minutes. Intramuscular: 10 to 20 minutes. Intravenous: Less than 5 minutes.
Crosses blood-brain barrier in moderate amounts; largely concentrated in liver.
Elimination: Renal: 80-90%. Fecal: 5-8%.
For more Absorption, Distribution and Excretion (Complete) data for LEUCOVORIN (10 total), please visit the HSDB record page.

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Metabolism / Metabolites
Hepatic and intestinal mucosal, the main metabolite being the active 5-methyltetrahydrofolate. Leucovorin is readily converted to another reduced folate, 5,10-methylenetetrahydrofolate, which acts to stabilize the binding of fluorodeoxyridylic acid to thymidylate synthase and thereby enhances the inhibition of this enzyme.
In vivo, leucovorin calcium is rapidly and extensively converted to other tetrahydrofolic acid derivatives including 5-methyl tetrahydrofolate, which is the major transport and storage form of folate in the body. /Leucovorin calcium/
Hepatic and intestinal mucosal, mainly to 5-methyltetrahydrofolate (active). After oral administration, leucovorin is substantially (greater than 90%) and rapidly (within 30 minutes) metabolized. Metabolism is less extensive (about 66% after intravenous and 72% after intramuscular administration) and slower with parenteral administration.

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Biological Half-Life
6.2 hours
Terminal half-life for total reduced folates: 6.2 hours.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Leucovorin (folinic acid; 5-formyltetrahydrofolic acid) and its levo- isomer, levoleucovorin, are folic acid derivatives that are normal components of breastmilk. Because leucovorin and levoleucovorin are used as therapeutic agents with potentially toxic drugs such as fluorouracil or methotrexate, the LactMed record of the drug it is used with should be consulted.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
~15%

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Toxicity Data
Mouse(iv): LD50 732 mg/kg

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Interactions
Concurrent use of leucovorin /with fluorouracil/ may increase the therapeutic and toxic effects of fluorouracil; although the two medications may be used together for therapeutic advantage, caution is necessary.
Exposure of tumor cells to reduced folates /like leucovorin/ before or with the fluoropyrimidines, 5-fluorouracil or 5-fluoro-2'deoxyuridine, results in a substantial increase in the activity of these drugs. Available evidence suggests that the mechanism of this synergism is a kinetic stabilization of complex formed between thymidylate synthase and fluorodeoxyuridylate that also involves a mole of the cofactor for the thymidylate synthase reaction, 5,10-methylenetetrahydrofolate. This effect results in an extended time of depletion of thymidine nucleotides with a resultant increased level of cell death.
Large dose of leucovorin may counteract the anticonvulsant effects of these medications: /barbiturate anticonvulsants, hydantoin anticonvulsants, primidone/.
The Sprague Dawley rat was used to demonstrate the effect of nitrous oxide, with and without folinic pretreatment, on reproductive indices and fetal development. ... Groups of animals were exposed to 70-75% nitrous oxide on day 9 of pregnancy with or without folinic acid 0.1 mg ip 12 hr before, and immediately before, exposure. Subsequent fetal development was compared with that of various control groups. There were no significant differences in fetal survival, but fetal wt were reduced in both groups exposed to nitrous oxide. Of the indices of skeletal maturity, the number of ossified sternebrae was reduced only in the nitrous oxide group not receiving folinic acid. The incidence of major skeletal abnormalities in the untreated nitrous oxide group was significantly increased to five times that of the control groups, whereas the incidence in the nitrous oxide group receiving folinic acid was not significantly different from control. It is concluded that pretreatment with folinic acid can at least partially reduce the teratogenic effects of nitrous oxide in the rat.

[1]. Inhibition of methotrexate-induced chromosomal damage by folinic acid in V79 cells. Mutat Res. 1998 Feb 2;397(2):221-8.

[2]. Effect of methotrexate and folinic acid on skeletal growth in mice. Acta Paediatr. 2003 Dec;92(12):1438-44.

Therapeutic Uses
Leucovorin is indicated for use in combination with agents such as fluorouracil or high-dose methotrexate, as second-line treatment of squamous cell head and neck carcinoma. /NOT included in US product labeling/
Antidotes
Leucovorin is indicated as a antidote to the toxic effects of folic acid antagonists such as methotrexate, pyrimethamine, or trimethoprim. Leucovorin also is indicated as a rescue after high-dose methotrexate therapy in osteosarcoma and as a part of chemotherapeutic treatment programs in the management of several forms of cancer. /Included in US product labeling/
Leucovorin is indicated to treat megaloblastic anemias associated with sprue, nutritional deficiency, pregnancy, and infancy when oral folic acid therapy is not feasible. Leucovorin is not recommended for use in the treatment of pernicious anemia or other megaloblastic anemias secondary to lack of vitamin B12, since it may produce a hematologic remission while neurologic manifestations continue to progress. /Included in US product labeling/
For more Therapeutic Uses (Complete) data for LEUCOVORIN (7 total), please visit the HSDB record page.

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Drug Warnings
Since allergic reactions have been reported following oral and parenteral administration of folic acid, the possibility of allergic reactions to leucovorin should be considered.
There is a potential danger in administering leucovorin to patients with undiagnosed anemia, as leucovorin may obscure the diagnosis of pernicious anemia by alleviating hematologic manifestations of the disease while allowing neurologic complications to progress. This may result in severe nervous system damage before the correct diagnosis is made. Adequate doses of Vitamin Bl2 may prevent, halt, or improve neurologic changes caused by pernicious anemia.
When leucovorin rescue is used in conjunction with high dose methotrexate therapy, the drugs should be administered only by physicians experienced in cancer chemotherapy, in centers where facilities for measuring blood methotrexate concentrations are available. Leucovorin is usually effective in counteracting severe methotrexate toxicity in these regimens, but toxic reactions to methotrexate may occur despite leucovorin therapy, especially when the half-life of methotrexate is increased (eg, renal dysfunction). Therefore, it is extremely important that leucovorin be administered until the blood concentration of methotrexate declines to nontoxic concentrations.
Since leucovorin calcium enhances the toxicity of fluorouracil, adjunctive therapy with leucovorin calcium and fluorouracil should be given only by, or under the supervision of, physicians experienced in cancer chemotherapy and in the use of antimetabolites. /Leucovorin calcium/
For more Drug Warnings (Complete) data for LEUCOVORIN (10 total), please visit the HSDB record page.

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Pharmacodynamics
Leucovorin is one of several active, chemically reduced derivatives of folic acid. It is useful as an antidote to drugs which act as folic acid antagonists. Leucovorin is a mixture of the diastereoisomers of the 5-formyl derivative of tetrahydrofolic acid (THF). The biologically active compound of the mixture is the (-)-l-isomer, known as Citrovorum factor or (-)-folinic acid. Leucovorin does not require reduction by the enzyme dihydrofolate reductase in order to participate in reactions utilizing folates as a source of “one-carbon” moieties. Administration of leucovorin can counteract the therapeutic and toxic effects of folic acid antagonists such as methotrexate, which act by inhibiting dihydrofolate reductase. Leucovorin has also been used to enhance the activity of fluorouracil.

C21H25CAN7O7.5H2O

601.58

511.112

1492-18-8

Folinic acid;58-05-9;Folinic acid calcium salt pentahydrate;6035-45-6;Folinic acid calcium hydrate;1097832-14-8

135403648

Off-white to light yellow solid powder

240-250ºC

1.411

198.1

7

10

9

34

911

1

C1C(N(C2=C(N1)N=C(NC2=O)N)C=O)CNC3=CC=C(C=C3)C(=O)N[C@@H](CCC(=O)O)C(=O)O

NPPBLUASYYNAIG-ZIGBGYJWSA-L

InChI=1S/C20H23N7O7.Ca.5H2O/c21-20-25-16-15(18(32)26-20)27(9-28)12(8-23-16)7-22-11-3-1-10(2-4-11)17(31)24-13(19(33)34)5-6-14(29)30;;;;;;/h1-4,9,12-13,22H,5-8H2,(H,24,31)(H,29,30)(H,33,34)(H4,21,23,25,26,32);;5*1H2/q;+2;;;;;/p-2/t12?,13-;;;;;;/m0....../s1

L-Glutamic acid, N-(4-(((2-amino-5-formyl-1,4,5,6,7,8-hexahydro-4-oxo-6-pteridinyl)methyl)amino)benzoyl)-, calcium salt (1:1), pentahydrate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

注意： (1). 请将本产品存放在密封且受保护的环境中（例如氮气保护），避免吸湿/受潮和光照。  (2). 该产品在溶液状态不稳定，请现配现用。

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

注意: 如下所列的是一些常用的体内动物实验溶解配方，主要用于溶解难溶或不溶于水的产品（水溶度<1 mg/mL）。 建议您先取少量样品进行尝试，如该配方可行，再根据实验需求增加样品量。

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注射用配方1: DMSO : Tween 80： Saline = 10 : 5 : 85 (如： 100 μL DMSO → 50 μL Tween 80 → 850 μL Saline)
*生理盐水/Saline的制备：将0.9g氯化钠/NaCl溶解在100 mL ddH ₂ O中，得到澄清溶液。
注射用配方 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL DMSO → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)
注射用配方 3: DMSO : Corn oil = 10 : 90 (如： 100 μL DMSO → 900 μL Corn oil)
示例: 以注射用配方 3 (DMSO : Corn oil = 10 : 90) 为例说明, 如果要配制 1 mL 2.5 mg/mL的工作液, 您可以取 100 μL 25 mg/mL 澄清的 DMSO 储备液，加到 900 μL Corn oil/玉米油中, 混合均匀。

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注射用配方 4: DMSO : 20% SBE-β-CD in Saline = 10 : 90 [如：100 μL DMSO → 900 μL (20% SBE-β-CD in Saline)]
*20% SBE-β-CD in Saline的制备（4°C，储存1周）：将2g SBE-β-CD (磺丁基-β-环糊精) 溶解于10mL生理盐水中，得到澄清溶液。
注射用配方 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (如： 500 μL 2-Hydroxypropyl-β-cyclodextrin (羟丙基环胡精)→ 500 μL Saline)
注射用配方 6: DMSO : PEG300 : Castor oil : Saline = 5 : 10 : 20 : 65 (如： 50 μL DMSO → 100 μL PEG300 → 200 μL Castor oil → 650 μL Saline)
注射用配方 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (如： 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
注射用配方 8: 溶解于Cremophor/Ethanol (50 : 50), 然后用生理盐水稀释。
注射用配方 9: EtOH : Corn oil = 10 : 90 (如： 100 μL EtOH → 900 μL Corn oil)
注射用配方 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL EtOH → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)

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口服配方 1: 悬浮于0.5% CMC Na (羧甲基纤维素钠)
口服配方 2: 悬浮于0.5% Carboxymethyl cellulose (羧甲基纤维素)
示例: 以口服配方 1 (悬浮于 0.5% CMC Na)为例说明, 如果要配制 100 mL 2.5 mg/mL 的工作液, 您可以先取0.5g CMC Na并将其溶解于100mL ddH2O中，得到0.5%CMC-Na澄清溶液；然后将250 mg待测化合物加到100 mL前述 0.5%CMC Na溶液中，得到悬浮液。

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口服配方 3: 溶解于 PEG400 (聚乙二醇400)
口服配方 4: 悬浮于0.2% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 5: 溶解于0.25% Tween 80 and 0.5% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 6: 做成粉末与食物混合

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注意: 以上为较为常见方法，仅供参考， InvivoChem并未独立验证这些配方的准确性。具体溶剂的选择首先应参照文献已报道溶解方法、配方或剂型，对于某些尚未有文献报道溶解方法的化合物，需通过前期实验来确定（建议先取少量样品进行尝试），包括产品的溶解情况、梯度设置、动物的耐受性等。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。