what is antimetabolites chemotherapy #in details


In the anticancer drugs various types like alkylating agents, antimetabolites, plants product, hormones etc are..

Here, are a discus the antimetabolite chemotherapy. 

ANTIMETABOLITES AGENTS :


antimetabolites chemotherapy


Folate antaginost :

Methotrexate :

Its commonly drugs used in anticancer drugs. Methotrexate drugs act on the cell dividing & s phase of the cell cycle. Methotrexate has also many effects produce like antineoplastic, immunosuppressant & anti-inflammatory etc. 

Methotrexate are inhibit the dihydrofolate reductase because of its structurally resembles with folic acid. Its prevent the conversion of dihydrofolic acid to tetrahydrofolic acid. Here, tetrahydrofolic acid are required for the purine & thymidylate. & these components are part of the RNA & DNA production. So, inhibit the tetrahydrofolate, also inhibit the DNA & RNA production.

Its administred in oral, i.v & i.m, etc. its bound to the plasma protein; very slow amount is cross the blood-brain barrier & most of the drugs are excreted in unchanged form through urine.

Methotrexate are used for the acute leukemias, Burkitt’s lymphoma & breast cancer. It's also a drug of choice for choriocarcinoma.

Very low dose methotrexate actually 7.5 to 25 mg once are used for rheumatoid arthritis. It also prevents joint erosion, inflammation. Methotrexate is the immunosuppressant effect are produced. Its also used in inflammatory bowel disease, psoriasis & oragan transplantation.

Adverse effect of the methotrexate are hepatic fibrosis, megaloblastic anemia, pancytopenia.

Purine antagonist :

Mercaptopurine & thioguanine :

These drugs are the inhibit the conversion of the inosine monophosphate to adenine & guanine nucleotides that also block the RNA & DNA. Also a these drugs are active their ribonucleotides which inhibit the nucleotide interconversion & purine ring biosynthesis. 

They are act on dividing cell as well as S phase of cell cycle. Mercaptopurine are also an immunosuppressant action produced. Also these both drugs are useful in choriocarcinoma, leukemia & some solid tumors.

Some other drugs frequently are given cancer patients that is allopurinol, allopurinol is drugs that a inhibit the xanthine oxidase in patients body. Xanthis oxidase are enzymes that convert the 6- mercaptopurine to 6-thiourea acid. So, allopurinol are inhibit the xanthine oxidase & retain the mercaptopurine and increase its activity.

Mercaptopurine are used mainly in acute lymphocytic leukemia. major Adverse effect of the 6- mercaptopurine is bone marrow depression. It also produces reversible jaundice. It also produces a common side effect like nausea, vomiting, etc.

pyrimidine antagonists :

Its also useful for the antifungal, antipsoriatic, antineoplastic.

Fluorouracil :

Fluorouracil are the drugs that are activated 5- fluoro – 2 – deoxyuridine monophosphate. Which the Fdump is the block the thymidylate synthetase.  

Thymidylate synthetase is converted the deoxyuridine acid to deoxythymidine acid, fluorouracil are the drugs that inhibit the thymidylate synthetase. So, block the thymidylate synthetase also block DNA synthesis. 

5- fluorouracil is currently used in solid malignancies, colon, stomach, rectum, liver, pancreas, head & neck, and urinary bladder anticancer. 5 – fluorouracil is administered through i.v infusion. The major toxicity of the 5 – fluorouracil are bone marrow depression. Also, the other side effect are nausea, vomiting, diarrhea, peripheral neuropathy.

Cytarabine :

Cytarabine is the inhibit the DNA polymerase as well as block the cytidilic acid. Cytarabine are act only in ‘S’ phase of the cell cycle. The primary use of the cytarabine is lymphoblastic leukemia in the liver as well as acute myelogenous. Its administered through rapid i.v injection or i.v infusion.

VINCA ALKALOIDS :

Vincristine & vinblastine :

Both are derived from the periwinkle plant. They are act on dividing cell & m phase in the cell cycle. Vincristine & vinblastine are differed in the toxicity & antitumor spectrum.

Vincristine & vinblastine are bind to the bita – tubulin & make a bita – tubulin complex.  To also inhibit its polymerization into microtubules. So, no intact mitotic spindle. That’s why cell division arrested in metaphase & not the growth of cell.

Use of the vinblastine is Hodgkin's disease, testicular tumors, carcinoma cancer & etc. also a Use of the vincristine is neuroblastoma, Hodgkin’s disease, leukemia, childhood tumors & others.

The adverse effect of vinblastine is anorexia, bone marrow suppression, nausea, vomiting & diarrhea. The adverse effect of vincristine is peripheral neuritis with paraesthesia. It’s minimal myelosuppressive action produce, to also a common side effect is constipation.

TAXENS :

Paclitaxel is the taxane drug derived from the bark of the western yew tree. The other docetaxel is the newer taxane.

The common mechanism of acion is the paclitaxel is bind to the bita – tubulin than stabilize the microtubules & formation of abnormal microtubules. So, due to producing the abnormal microtubules inhibit the mitosis.

Its administered through i.v infusion. Paclitaxel are used in ovarian, lung, esophageal, breast, bladder cancer.  Also a produce some adverse effect like myalgia, bone marrow suppression, peripheral neuropathy, hypersensitivity reaction etc.

CAAMPTOTHECINS :

Topotecan & irrinotecam are the drugs that include in camptothecins analogues.

The common mechanism action of the camptothecins are binds to stabilize DNA – topoisomerase 1 complex & inhibit the resealing function. Also a its strand breaking action is not affected. So, that’s why produce the cell death.

Comptothecins are use in advance ovarian, lung & colorectal cancer. The common adverse effect is gastrointestinal disturbance & bone marrow suppression.

antimetabolites chemotherapy

EPIPODOPHYLLOTOXINS 

Epipodophyllotoxins are act on S-G2 phases of the cell cycle.

Teniposide & etoposide are make a complex with DNA & topoisomerase 2. Then that complex prevents the resealing the broken DNA strand. And finally, it produce cell death.

Etoposide is effective in AIDs related to Kaposi’s sarcoma & non – Hodgkin’s lymphoma. Also, a used in lung cancer & testicular with cytotoxic drugs.

The adverse effect of etoposide is vomiting, diarrhea, hepatotoxicity & bone marrow suppression.

ANTICANCER ANTIBIOTICS :

The common mechanism of action of anticancer antibiotics is direct act on DNA. This all drugs are bind to DNA through intercalation between adjoining nucleotide pairs on DNA. Also a block the transcription of DNA.

Actinomycine D :

Actinomycin are mainly used in the treatment of Wilm’s tumors, ewings sarcoma & choriocarcinoma. The most common side effect is bone marrow suppression & GI side effects produced. Its administered through intravenously.

Mitomycin C :

Mitomycin are mainly used in GI tumors, bladder cancer, cervical cancer etc. also a major adverse effect is a bone marrow depression & nephrotoxicity. Its act as a alkylating agent.

Bleomycin :

Bleomycin are mainly used in treatment of ovarian & testicular tumors a well as Hodgkin's lymphoma. Also a major side effect is pulmonary fibrosis & hyperpigmentation of the skin. Very little produced bone marrow depression.

ENZYME :

L – asparaginase :

L – asparaginase is isolated from the E.coli bacteria. L – asparaginase is an enzyme that convert the asparagine to aspartic acid. Asparagine are required for the protein synthesis. In normal cell contain aspargine synthesis enzyme, but in cancer chancer lack of this enzyme.

L – asparaginase are enzyme that degrades the asparagine to aspartic acid. So, its neoplastic cells are deprived of asparagine, which resulting to a destroy the cell.

Used in treatment of acute lymphoblastic leukemia. another adverse effect is hyperglycemia, headache, hallucinations, coma, confusion, haemorrhage & other hypersensitive reaction.

MISCELLANEOUS AGENTS :

Hydroxyurea :

Its act the s phase of the cell cycle. Hydroxyurea are inhibit DNA synthesis by inhibit the ribonucleoside diphosphate reductase. Mainly used in polycythemia vera, psoriasis. GML. The major side effect is thrombocytopenia, bone marrow depression, anaemia.

In cancer treatment bone marrow depression & GI effect are the major side effect produced.