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Phar 509 > Antimetabolites > Flashcards

Antimetabolites Flashcards

1
Q

What are antimetabolites?

A

Chemicals that inhibit action of metabolites therefore, INTERFERE WITH NORMAL METABOLISM

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2
Q

What phase of the cell cycle do antimetabolites act in

A

S phase: synthesis and replication of DNA

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3
Q

What is the two major mechanisms of antimetabolits

A

INHIBIT PRODUCTION of dexoyribonucleoside triphosphates (inhibits the replication of the DNA), INCORPORATE INTO THE DNA (cytotoxic effect on the cell)

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4
Q

What are the three different types of antimetabolites

A

Anti-purines, anti-folates, and anti-pyrimidines

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5
Q

What pathway for synthesizing DNA/RNA does tumors rely on

A

De novo pathway

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6
Q

What are the purines, pyrimidines

A

Adenine and guanine/ cytosine, uracil, and thymine

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7
Q

What are the two major anti-purines and what do they substitute for

A

6-mercatopurine (6-MP) –> Adenosine

6-thioguanine (6-TG) –> Guanine

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8
Q

What is the breaking point in the De novo purine nucleotide biosythensis

A

Inosine monophosphate

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9
Q

What are the two MOAs of anti-purines

A

Inhibit nucleotide synthesis at several step of de novo biosynthesis, incorporation into nucleic acids

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10
Q

Which antipurine blocks IMP from being converted to AMP

A

6-MP

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11
Q

T/F: When anti-purines are incorportated into DNA the repair pathways have trouble distinguishing them from regular purines but DNA/RNA polymerase never replicate them

A

True

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12
Q

What are the side effects of 6-MP

A

fatigue, diarrhea, nausea, skin rash, alopecia

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13
Q

What are the side effects of 6-TG

A

leukopenia, neutropenia, thrombocytopenia, anemia, anorexia

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14
Q

What are the two groups for anti-pyrimidines

A

Cytdine analogs and fluropyrimidine analogs

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15
Q

What are the cytdine analogs, fluropyrimindine analogs

A

Cytarabine and gemcitabine/ 5-flurouracil and capecitabine

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16
Q

What are the two MOA of 5-flurouracil

A

Inhibits synthesis of thymidine nucleotide (major), incorporates into RNA and DNA

17
Q

What is the enzyme that interactes with 5-flurouracil not allowing for thymidine synthesis

A

Thymidylate synthase

18
Q

What is a difference between 5-flurouracil and capectiabine that also connects the two

A

Capecitabine is a prodrug that to 5-FU by the liver

19
Q

What tumors are most sensitive capecitabine and what cancers are usually treated by capecitabine

A

Tumors that overexpress thymidine phosphorylase, breast and colon cancers

20
Q

Since 5-FU and capecitabine can be fatal what drugs can be given to reverse action

A

Uridine triacetate

21
Q

Which drug contains a combination of fluropyrimidine analogs

A

Trifluridine/Tipiracil (TFT/TPI)

22
Q

What is the MOA of TFT

A

The triphosphate form of TFT/TPI can be incorporated into DNA inducing DNA fragmentation, inhibits thmidylate synthase reducting the nucleotide pool levels required for DNA replication

23
Q

What is the TPI MOA

A

Inhibits thymidine phosphorylase, increase bioavailabitly of TFT

24
Q

What is the MOA of cytarabine, what type of cancer does it treat, toxicities

A

Incorporates into DNA and prevents DNA elongation/ leukemias/ myelosuppression, mucositis, fever, pains

25
Q

What is the Dual MOA of gemcitabine, biggest setback

A

Inhibition of ribonuclotise reductase (ribonucleotides cannot convert to deoxy-ribonucleotides), Triphosphate form incoporates into DNA/ Half-life of 8 mins

26
Q

Where does folate (vitamin B9) come from

A

Food (leafy greens)

27
Q

What is the role of folate in thymidine synthesis

A

Folate aids in the co-factor N5,N10-methylene THF (essential for converting dUMP into dTMP)

28
Q

What is the important co-factor in purine synthesis, how is it acquired

A

Formyltetrahydrofoloate, folate is converted to tetrahydrofolfate by dihydrofolate reductase (DHFR)

29
Q

What is the MOA of methotrexate

A

Competitively Inhibits DHFR due to 1000 fold higher affinity (inhibts purine and pyrimidine synthesis)

30
Q

What are the side effects of methotrexate

A

Memory loss (neurotoxicity), heptaotoxicity, myelosuppresion, GI toxicitites

31
Q

T/F: Methotrexate is NOT safe in pregnancies

A

True

32
Q

What medication is used as a rescue from methotrexate

A

Leucovorin (Folinic acid)

33
Q

What category of anti-metabolite is pralatrexate, why is it special, which cancers is it used against

A

Anti-folate, accumulates preferentially in cancer cells and has high tumor uptake, refractory peripheral T- cell lymphoma

34
Q

What are the the three enzymes that pralatrexate inhibits

A

DHFR, Thymidylate synthase, GARFT

Phar 509 (22 decks)

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