甲氨蝶呤片（Methotrexate Tablets）.docVIP

甲氨蝶呤片（Methotrexate Tablets） Methotrexate Tablets (Methotrexate Tablets) The main ingredients of this product are methotrexate. The chemical name: L- (+) -N-{4-[(2,4- two -6- amino pteridine base) methylamino] benzoyl glutamic acid}. [traits] This product is light orange and yellow. [pharmacology and toxicology] Tetrahydrofolate is important in vivo synthesis of pyrimidine and purine nucleotide coenzyme deoxynucleotide, this product is a kind of folate reductase inhibitor, which mainly inhibited dihydrofolate reductase cannot restore the physiological activity of dihydrofolate tetrahydrofolate, which enables the transfer of a carbon radical biosynthesis of purine nucleotides and pyrimidine nucleotides in DNA biosynthesis is blocked, resulting in suppression. In addition, this product also has inhibitory effect on thymus nucleotide synthetase, but the inhibition of RNA and protein synthesis was relatively weak, the main role in the S phase of the cell cycle, is a cell cycle specific drug, the G1/S phase cells also have delayed effect on G1 cells with weak. [pharmacokinetics] When the dosage is less than 30mg/m2, the oral absorption is good, and the serum concentration reaches the peak at 1~5 hours. The metabolism of hepatocytes is partly converted to glutamate, and partly through the metabolism of gastrointestinal bacteria. Mainly through the kidneys (about 40% to 90%) excretion, mostly excreted by the prototype medicine; less than 10% of the drugs excreted through bile, T1/2a for 1 hours; T1/2b for two chamber type: the initial 2~3 hours; the end of 8~10 hours. A small amount of methotrexate and its metabolites can be stored in the kidney and liver tissues for several months in a combined form, and the clearance rate of the product is markedly slowed down in cases with pleural effusion or peritoneal effusion. The rate of individual difference was great, and the older patients were even worse. [indications] (1) acute leukemias of various types, especially acute lympho