Methotrexate Tablets IP 15 mg

Product Description

This folic acid analogue is one of the oldestand highly efficacious antineoplastic drugswhich acts by inhibiting dihydrofolate reductase(DHFRase), thus blocking the conversion ofdihydrofolic acid (DHFA) to tetrahydrofolic acid(THFA). Utilizing the folate carrier it enters intocells and is transformed to more active polyglutamate form by the enzyme folypolyglutamatesynthase (FPGS). Tetrahydrofolic acid is anessential coenzyme required for one carbontransfer reactions in de novo purine synthesisand amino acid interconversions. The inhibitionis pseudo irreversible because Mtx has 50,000times higher affinity for the enzyme than thenormal substrate.

Methotrexate is absorbed orally, 50% plasmaprotein bound, little metabolized and largelyexcreted unchanged in urine. Salicylates, sulfonamides, dicumerol displace it from protein binding sites. Aspirin and sulfonamidesenhance toxicity of Mtx by decreasing its renaltubular secretion.