Anti-metabolites

Question 1

Methotrexate

Answer 1

Folic acid analog that targets S phase and inhibits human dihydrofolate reductase which result in inhibition of nucleotide synthesis(Thymidine) since the cell can’t produce Tetrahydrofolate.

Question 2

How methotrexate get in to the cells

Answer 2

Via folic acid transport system or through being conjugated to glutamates to serve as a depot of active drug.

Question 3

How resistance develops in methotrexate

Answer 3

Impaired transport into cells and polyglutamate formation, altered dihydrofolate reductase, and decrease thymidylate synthase by establishing other pathway.

Question 4

Leucovorin

Answer 4

Pre-activated folate compounds to save only normal cells up on massive dose of methorexate is given.

Question 5

5-fluorouracil

Answer 5

Pyrimidine analogues that is structurally similar to thymidine to synthesize FUDP which can be either FdUMP(DNA) to inactivate thymidylate synthetase or FUTP(RNA).

Question 6

Cytarabine

Answer 6

modified sugar molecule of nucleotide, called arabinose sugar. Once activated to ara-CTP, it inhibits DNA polymerase

Question 7

How antimetabolite resistance develops

Answer 7

Change in targets enzymes, Decrease activation and access to target cells, increase inactivation.