Methotrexate is a drug used to treat cancer, psoriasis, rheumatoid arthritis, lupus, and to induce miscarriage in women who have had ectopic pregnancies. Question 1:
Pharmacokinetics describes how the body affects a certain type of drug after administration through absorption, metabolism, distribution and excretion while travelling throughout the body.
Absorption
Absorption is defined as the movement of a drug through the bloodstream. Absorption of a drug is affected by the solubility of the drug and the route of administration; entral, parenteral route, inhalation and topical routes.
• The enteral route consists of Oral, Sublingual, rectal. The oral route is through the alimentary canal and it comes in the form of powders, capsules, tablets …show more content…
The liver is the primary site of drug metabolism but, with certain drugs, other tissues e.g. kidneys, lungs and intestinal mucosa, may also be involved to a limited extent in the process.
A small percentage of methotrexate is actually metabolised. Methotrexate is metabolised to polyglutamat derivatives and become active dihydrofolate reductase (DHFR) inhibitors. These polyglutamated derivatives result in the storage on intracellular storage of methotrexate.
Excretion
Excretion describes the process of how the drug is eliminated from the body. Methotrexate’s main route of elimination is through the renal system, however about 30% of Methotrexate excretion occurs through biliary elimination.
Methotrexate is removed from the body through the kidneys by its tubular secretion-reabsorption cycle and is removed from the body by urine. In biliary elimination many metabolites of drugs created in the liver are excreted into the intestinal tract in the bile. Drugs are transferred from the plasma into the bile through the hepatocytes. Methotrexate in bile enters the GI tract after storage in the gallbladder. It can then be excreted from the body by the stools.
Drug’s bioavailability and …show more content…
Mouth ulcers can also occur due to methotrexate being a folic acid antagonist but it is less likely to occur if folic acid supplements are taken. Folic acid supplements can also usually control gastrointestinal side effects i.e. include gingivitis, nausea, pharyngitis, stomatitis, anorexia, hematemesis, melena, GI ulcer’s and bleeding.
Methotrexate can have adverse effects that have Hematologic side effects such as myelosuppression; suppression of blood cells and platelets in the bone marrow. Methotrexate suppresses haematopoiesis, which can cause anaemia, aplastic anaemia, thrombocytopenia, leucopoenia, lymphadenopathy leukopenia, and neutropenia. Immunosuppression effects such as infections, boils and acne and loss of hair are also adverse reactions to the drug. Renal failure, severe skin reactions and photosensitivity have been reactions associated with high dose therapy of Methotrexate.
Contraindications of Methotrexate
Pharmacokinetics describes how the body affects a certain type of drug after administration through absorption, metabolism, distribution and excretion while travelling throughout the body.
Absorption
Absorption is defined as the movement of a drug through the bloodstream. Absorption of a drug is affected by the solubility of the drug and the route of administration; entral, parenteral route, inhalation and topical routes.
• The enteral route consists of Oral, Sublingual, rectal. The oral route is through the alimentary canal and it comes in the form of powders, capsules, tablets …show more content…
The liver is the primary site of drug metabolism but, with certain drugs, other tissues e.g. kidneys, lungs and intestinal mucosa, may also be involved to a limited extent in the process.
A small percentage of methotrexate is actually metabolised. Methotrexate is metabolised to polyglutamat derivatives and become active dihydrofolate reductase (DHFR) inhibitors. These polyglutamated derivatives result in the storage on intracellular storage of methotrexate.
Excretion
Excretion describes the process of how the drug is eliminated from the body. Methotrexate’s main route of elimination is through the renal system, however about 30% of Methotrexate excretion occurs through biliary elimination.
Methotrexate is removed from the body through the kidneys by its tubular secretion-reabsorption cycle and is removed from the body by urine. In biliary elimination many metabolites of drugs created in the liver are excreted into the intestinal tract in the bile. Drugs are transferred from the plasma into the bile through the hepatocytes. Methotrexate in bile enters the GI tract after storage in the gallbladder. It can then be excreted from the body by the stools.
Drug’s bioavailability and …show more content…
Mouth ulcers can also occur due to methotrexate being a folic acid antagonist but it is less likely to occur if folic acid supplements are taken. Folic acid supplements can also usually control gastrointestinal side effects i.e. include gingivitis, nausea, pharyngitis, stomatitis, anorexia, hematemesis, melena, GI ulcer’s and bleeding.
Methotrexate can have adverse effects that have Hematologic side effects such as myelosuppression; suppression of blood cells and platelets in the bone marrow. Methotrexate suppresses haematopoiesis, which can cause anaemia, aplastic anaemia, thrombocytopenia, leucopoenia, lymphadenopathy leukopenia, and neutropenia. Immunosuppression effects such as infections, boils and acne and loss of hair are also adverse reactions to the drug. Renal failure, severe skin reactions and photosensitivity have been reactions associated with high dose therapy of Methotrexate.
Contraindications of Methotrexate