Reaction Paper On Methotrexate

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Methotrexate (MTX), is an antifolate drug that was first developed to treat certain types of cancer. The use in cancer therapy is at higher doses whereas its use in rheumatic diseases is at much lower doses. It was found that the addition of a maintenance therapy following remission comprising of 6 mercaptopurine daily along with methotrexate weekly resulted in higher chances of remission. As per the current ALL protocols, induction and consolidation therapy is followed by oral 6 MP/ methotrexate maintenance therapy is given until 2 to 3 years from diagnosis. The enzyme dihydrofolic acid reductase (DHFR), which acts by reducing dihydrofolates to tetrahydrofolates, is inhibited by methotrexate. The tetrahydrofolates that are formed by means of this enzyme are used in the synthesis of purine nucleotides and thymidylate as one - carbon carriers. Methotrexate, therefore, interrupts DNA synthesis, and interferes with its repair…show more content…
It is usually completely absorbed when administered parenterally.. About 50% of methotrexate in the serum is bound to plasma proteins. It can therefore be displaced by various compounds including sulfonamides, salicylates, tetracyclines, chloramphenicol, and phenytoin. Methotrexate, when given orally or parenterally, does not cross the blood-CSF barrier in therapeutic concentrations. However, intrathecal administration yields high CSF concentrations of the drug. Polyglutamated compounds are formed from methotrexate due to hepatic metabolism that may be also be reverted to form MTX by the enzymes hydrolases. The terminal half-life of methotrexate is nearly three to ten hours in those receiving doses less than 30 mg/m2 and can be 8 - 15 hours for those receiving higher doses of the drug. The primary route of elimination is renal and excretion and is dependent upon the dose as well as route of
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