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Oncology > Chemotherapy and antineoplastics > Flashcards

Chemotherapy and antineoplastics Flashcards

1
Q

What are your folic acid analagoues?

A

Methotrexate

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2
Q

What the pyrimidine analagoues?

A

5-Fluorouracil

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3
Q

Cytidine analogues?

A

cladribine, azacitidine, decitabine, gemcitabine

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4
Q

purine analogues?

A

6-thiopurine analagoues

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5
Q

What is an antimetabolite?

A

substance that competes with repplaces or inhibits a specific metabolite-intereferes with normal cell metabolic functioning

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6
Q

Antimetabolites MOA:

A

competititve inhibition-halts cell growth and cell division
intereferes with DNA synthesis and cellular function

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7
Q

Folate is known as?

A

Vitamin B 9

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8
Q

Folic acid is converted to? (active form)

A

tetrahydrofolate (FH4)

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9
Q

FH4 does what?

A

methyl group donor (reducing folic acid) for the synthesis of thymidine

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10
Q

Folic acid analogues MOA?

A

block the formation of thymidine—>purine nucleotide imbalance, ultimately slowing DNA synthesis

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11
Q

Methotrexate MOA

A

directly inhibits folate-dependent enzymes of de novo purine synthesis and thymidylate synthesis

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12
Q

MTX intereferes with ______ and inhibits ________

A

FH4 metabolism
inhibits DNA replication

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13
Q

Folate antagonists kill during which phase of the cell cylce>

A

S phase (most effective when cells proliferate rapidly)

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14
Q

Can terminate toxic effects of MTX using?

A

Leucovorin (repletes FH4 cofactors)

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15
Q

Leucovorin MOA?

A

converts into FH4 and bypasses the inhibition of DHFR by MTX

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16
Q

Folic acid analogues are?

A

polar-poorly crosses the BBB
Need: folate receptor, transporter that is active in low PH, and a reduced folate transporter

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17
Q

MTX inside cell» enzyme folylpolyglutamate synthesase (FPGS) does what?

A

adds additional glutamyl residues

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18
Q

polyglutamation serves as>

A

mechanism for ion trapping within cell, prolonged retention of MTX, and greater affinity

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19
Q

MTX-PGs constitute?

A

intracellular storage forms of folates and folate analogues that increase inhibitory potency of Thymidylate synthase (TS).

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20
Q

Resistance to antifolates?

A

impaired transport of MTX
Altered forms of DHFR that have decreased affinity
increased concentrations of intracellular DHFR through gene amplification
decreased ability to synthesize MTX-PGs
increased drug efflux transporter of multi resistant protein

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21
Q

Large doses of MTX

A

must be given IV as they are absorbed incompletely in GI tract

22
Q

MTX IV, drug disappears in triphasic fashion meaning?

A

rapid distribution
renal clearance of 2-3 hr
terminal phase of about 8-10 hr

23
Q

MTX excretion?

A

90% excreted unchanged in the urine—>dose adjust for renal failure

24
Q

MTX and highly protein bound drugs interaction?

A

may displace MTX from albumin and increase toxicity
Sulfonamides, salicylates, phenytoin, tetracyclines

25
Q

Vitamin C and MTX?

A

could acidify the urine and increase MTX in plasma

26
Q

MTX is critical in the management of what cancer in children?

A

Acute Lymphoblastic leukemia (ALL)

27
Q

What are the primary toxicities of antifolates?

A

bone marrow and intestinal epithelium

28
Q

pyrimidine analogues are _____ phase specific agents

29
Q

Pyrimidine analogues are AKA

A

nucleoside analogues, antimetabolites interfering or competing with nucleoside triphosphates in synthesis of DNA and RNA

30
Q

Which agents are analogues of cytosine?

A

azacitidine, decitabine, cytarabine, gemcitabine
(DAC-G)

31
Q

Which agents are analogues of uracil?

A

Fluorouracil, floxuridine, capecitabine
(FCF)

32
Q

Fluorouracil (5FU) MOA:

A

inhibits thymidylate synthase (TS)—>DNA strand breakage dude to TS inhibition

33
Q

what is the active metabolite of 5FU?

34
Q

how is 5FU administered?

A

IV (parenterally) due to oral ingestion being unpredictable

35
Q

5FU excretion in urine?

A

only 5-10% of dose is excreted in urine

36
Q

5FU is inactivated by?

A

reduction of pyrimidine ring carried out by Dihydriopyrimidine Dehydrogenase (DPD)

37
Q

Leucovorin and 5FU?

A

enhances rsponse to 5FU but enhances both cytotoxicity and toxicity of Fluorouracil

38
Q

MTX and 5FU?

A

MTX when given prior to 5FU can enhance activity of 5FU

39
Q

Capecitabine is a ?

A

orally administered prodrug of 5FU

40
Q

Cytarabine and Gemcitabine MOA:

A

structural analogue of cytidine and deoxycytidine

41
Q

Cytarabine and Gemcitabine are

A

potent competitive inhibitors (triphospahte form) of DNA polymerase

42
Q

Decitabine MOA?

A

induces double strand DNA breaks

43
Q

Azacitidine MOA?

A

enter cells by ENT1 and gets incorporated into DNA causing demethylation resulting in tumor cell differentiation and apoptosis.

44
Q

Purine analogues do what?

A

interfere with or compete with nucleoside triphosphates in the synthesis of DNA or RNA
-Adenine and Guanine

45
Q

Which drugs are purine analogues?

A

Mercaptopurine (6MP) and Thioguanine (6TG)
(both are prodrugs)

46
Q

Purine analogues inhibit?

A

T-lymphocytes (reducing CD4 counts)
this requires prophylactic medications for infection prophylaxis

47
Q

6MP can be metabolized to inactive metabolite BY?

A

Xanthine Oxidase
dose reduce if given with allopurinoll

48
Q

Cladribine is a ?

A

prodrug and requires phosphorylation by deoxycytidine kinase to 2CdATP

49
Q

Cladribine AKA?

A

Adenosine deaminase-resistant purine analogue

50
Q

Fludarabine Phosphate is?

A

a prodrug (purine analogue)

51
Q

Pentostatin is a

A

Purine analogue
inhibitor of adenosine deaminase (ADA)
causes myelosuppression

Oncology (10 decks)

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