The percentage of aberrant cells (Abs) and micronucleated binucleated cells (MNBN) increased concentration-dependently when MTX was used alone. The nuclear division index (NDI) falls as MTX concentration rises. Similarly, at every MTX concentration that was examined, the mitotic index (MI) likewise dropped. Leucovorin added at 50 μg/mL dramatically decreased the percentages of MNBN (40-68%) and Abs (36-77%). Additionally, at 5 μg/mL leucovorin, inhibitory effects were noted (12% to 54% for MNBN and 20% to 61% for Abs) [1].

After receiving methotrexate (MTX) for three weeks, treatment with leucovorin (7.0 mg/kg; i.p.; every other day; for Balb/c juvenile male mice) appeared to counteract this growth suppression (MTX reduces bone growth in mice when administered chronically)[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

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

Note: (1). Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.  (2). This product is not stable in solution, please use freshly prepared working solution for optimal results.

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

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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