Wednesday - Fitz - b12/folate

Question 1

When do you stop a chemo drug

when do you switch

Answer 1

stop with bone marrow suppression

switch with tumor resistance

Question 2

Primary resistance of a tumor

aquired resistance

multidrug resistance - what drugs do you see it in

Answer 2

cancer cell is innately resistant

after exposure, get acquired resistance (duh)

give one drug - tumor becomes resistant to many - see it in natural products (p glycoprotein effluxes them), alkylating agents

Question 3

function of B12 with regards to DNA synthesis

Answer 3

converts methyl THF in the liver into THF that can be used for DNA synthesis

Question 4

function of leucovorin

Answer 4

allows the cells to get tetrahydrofolate without in being synthesized from folate

Question 5

What can you detect to determine if someone is b12 deficient

Answer 5

increase in homocystiene (which is normally converted into methionine)

Question 6

4 biochemical pathways folate is used in

Answer 6

amino acid metabolism
methionine synthesis
purine synthesis
pyrimidine synthesis

Question 7

what is upregged in some cancers that causes methotrexate to work better

Answer 7

folate CARRIER

Question 8

folate receptor vs reduced folate carrier

Answer 8

folater receptor - high affinity, low capacity, high sensitiviry

RFC - low affinity, high capacity.

Question 9

why is folate supplementation bad for the elderly

Answer 9

folate can hide a B12 deficiency until you get irreversible neural defects

Question 10

The one drug that prevents dna synthesis and is not an antimetabolite

Answer 10

hydroxyurea

(blocks ribonuleotide reductase, puts cells in radiation sensitive cell cycle phase G0

all others that block DNA synthesis are antimetabol`ites

Question 11

what rescues normal cells from MTX

Answer 11

leucovorin

Question 12

what helps with MTX overdose

Answer 12

glucoparidase - destroys MTX and reduces its concentration

Question 13

what type of urine ph will help with excretion of MTX

Answer 13

basic ph

Question 14

What drug is converted into 5-fu only in cancer cells and what enzyme does it?

Answer 14

capecitabine

Thymidine phosphorylase

Question 15

what causes tumor lysis syndrome
what treats it
what enzyme is inhibited during the tx of TLS

Answer 15

6-MP among others (anytime you kill a lot of cells you can get TLS)

allopurinol (TLS can cause gout like Sx with high uric acid)

Xanthine oxidase