Methotrexate Lpf
Brand names,
Methotrexate Lpf
Analogs
Methotrexate Lpf
Brand Names Mixture
Methotrexate Lpf
Chemical_Formula
C20H22N8O5
Methotrexate Lpf
RX_link
http://www.rxlist.com/cgi/generic/mtx.htm
Methotrexate Lpf
fda sheet
Methotrexate Lpf
msds (material safety sheet)
Methotrexate Lpf
Synthesis Reference
Seeger et al.; J.Amer.Chem.Soc.; 71; 1753,1757(1949)
Methotrexate Lpf
Molecular Weight
454.44 g/mol
Methotrexate Lpf
Melting Point
195 oC
Methotrexate Lpf
H2O Solubility
2600 mg/L
Methotrexate Lpf
State
Solid
Methotrexate Lpf
LogP
-1.08
Methotrexate Lpf
Dosage Forms
Liquid; Powder for solution; Solution; Tablet (oral, in 5 mg, 7.5 mg, or 10 mg)
Methotrexate Lpf
Indication
For the treatment of gestational choriocarcinoma, chorioadenoma destruens and hydatidiform mole. Also for the treatment of severe psoriasis and severe, active, classical or definite rheumatoid arthritis.
Methotrexate Lpf
Pharmacology
Methotrexate is an antineoplastic anti-metabolite. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (of the cell cycle), stopping normal development and division. Methotrexate inhibits folic acid reductase which is responsible for the conversion of folic acid to tetrahydrofolic acid. At two stages in the biosynthesis of purines and at one stage in the synthesis of pyrimidines, one-carbon transfer reactions occur which require specific coenzymes synthesized in the cell from tetrahydrofolic acid. Tetrahydrofolic acid itself is synthesized in the cell from folic acid with the help of an enzyme, folic acid reductase. Methotrexate looks a lot like folic acid to the enzyme, so it binds to it quite strongly and inhibits the enzyme. Thus, DNA synthesis cannot proceed because the coenzymes needed for one-carbon transfer reactions are not produced from tetrahydrofolic acid because there is no tetrahydrofolic acid. Methotrexate selectively affects the most rapidly dividing cells (neoplastic and psoriatic cells). Methotrexate is also indicated in the management of severe, active, classical, or definite rheumatoid arthritis.
Methotrexate Lpf
Absorption
Generally well absorbed with a mean bioavailability of about 60%.
Methotrexate Lpf
side effects and Toxicity
Symptoms of overdose include bone marrow suppression and gastrointestinal toxicity. LD50=43mg/kg(orally in rat).
Methotrexate Lpf
Patient Information
Patients should be informed of the early signs and symptoms of toxicity, of the need to see their physician
promptly if they occur, and the need for close follow-up, including periodic laboratory tests to monitor
toxicity.
Both the physician and pharmacist should emphasize to the patient that the recommended dose is taken weekly in
rheumatoid arthritis and psoriasis, and that mistaken daily use of the recommended dose has led to fatal toxicity.
Patients should be encouraged to read the Patient Instructions sheet within the Dose Pack. Prescriptions should not
be written or refilled on a PRN basis.
Patients should be informed of the potential benefit and risk in the use of methotrexate. The risk of effects on
reproduction should be discussed with both male and female patients taking methotrexate.
Methotrexate Lpf
Organisms Affected
Humans and other mammals