Antifolate cancer drugs are: (PGI Nov 2009)
Correct Answer: Methotrexate
Description: Ans:A (Methotrexate) Folate AntagonistMethotrexate'-'Trimethoprim4Pyrimethamine4PemetrexedMethotrexate (MTX) It is a folic acid antagonistQ that binds to the active catalytic site of dihydrofolate reductase (DHFRQ, interfering with the synthesis of the reduced form that accepts one-carbon units. Lack of this cofactor interrupts the de novo synthesis of thymidylate, purine nucleotides, and the amino acids serine and methionine, thereby interfering with the formation of DNA, RNA, and key cellular proteins.PemetrexedIt is a pyrrolopyrimidine antifolate analogue'Jwifh activity in the S phase of the cell cycle. As in the case of MTX, it is transported into the cell via the reduced folate carrier and requires activation by the enzyme FPGS to yield higher polyglutamate forms.While this agent targets DHFR and enzymes involved in de novo purine nucleotide synthesis, its main site of action is via inhibition of thymidylate synthase.At present, this anti folate is approved for use in combination with cisplatin in the treatment of mesothelioma - and as a single agent in the second-line therapy of non-small cell lung cancer.Cisplatin# Although the precise mechanism of action of cisplati n is still undefined, it is thought to exert its cytotoxic effects in the same manner as alkylating agents.It kills cells in all stages of the cell cycle, binds DNA through the formation of intrastrand and interstrand cross-links, and inhibits DNA synthesis and function. The primary binding site is the iY7 position of guanine1) but covalent interaction with adenine and cytosine also occursDrug Acting Directly on Cells (Cytotoxic Drugs)1. Alkylating eventsNitrogen mustardQMechlorethamine (Mustine HC])CyclophosphamideQIfosfamideQChlorambucilMelphalanQ# Ethyleninine:Thio-TEPA # Alkyl sulfonate:BusulfanQ# Nitrosoureas:Carmustine (BCNU),Lomustine (CCNU]# Triazine:Dacarbazine (DT1C)2. Antimetabolites#Folate antagonistMethotrexate (Mtx)# Purine antagonist6-Mercaptopurine (6-MP)6-Thioguanine (6-TG)AzathioprineQFludarabineQ# Pyrimidine antagonist5-FlurouracilQ (5-FU),Cytarabine (cytosine arabinoside)3. Vinca alkaloidsVincristine (Oncovin],Vinblastine4. TaxanesQPaclitaxelQDocetaxei5. Epipodophyllo toxinQEtoposideQ6. Camptothecin analoguesTopotecanQIrinotecanQ7. AntibioticsQActinomycin DQ(Dactinomycin)DoxorubicinQDaunorubicinQ (Rubidomycin)Mitoxantrone8. MiscellaneousHydroxyureaQProcarbazine,L-Asparaginase,CisplatinQCarboplatinImatinibQ
Category:
Pharmacology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now