Chemo-4
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- What antimetabolite(s) has the greatest effect on cells in the S phase?
- methotrexate and cytosine arabinose
- What is the MOA of methotrexate?
- a folic acid antagonist (competes for binding site on the enzyme dihydrofolate reductase preventing the synthesis of folate)
- What is the antidote for cytotoxicity of methotrexate?
- leucovorin
- How does leucovorin provide it's antidote effect from methotrexate toxicity?
- provides folate for cell
- What drug(s)combination with methotrexate can lead to severe folate deficiency?
- trimethoprim/sulfa antibiotic
- What percentage of the dose of methotrexate is excreted in 24 hours and by what means?
- 90% of the dose is excreted in 24 hours and primarily excreted in the urine
- What is the MOA of cytosine arabinoside?
- inhibition of DNA polymerase
- What is cytosine arabinoside used for the treatment of?
- used to treat CNS lymphoma as well as in CSF, also used to treat leukemias
- What antimetabolite do you never want to use in cats because of death?
- (5FU), 5-Flurouracil
- What is the mechanism of action of 5- flurouracil (5FU)?
- it is a pyrimidine analog that exerts cytotoxic effects by inhibiting thymidylate synthetase; therefore inhibiting DNA synthesis and some RNA synthesis
- What spp. of animal does 5FU normally cause neurotoxicity?
- dogs
- What reason do you use 5FU in large animals?
- skin carcinomas and solar keratosis (2-4 month therapy)
- What is the protocol for an accidental treatment of 5FU in cats?
- there is nothing you can do, there is no taking back the administration
- What are the platinum drugs?
- Cisplatin and Carboplatin
- What is the action of L-Asparginase?
- enzyme cleaves extracellular pools of L-asparagine which is required by neoplastic lymphoid cells and is most effective in G1 phase
- Why is folate important for the body?
- Because it is needed for the production of purine nucleotides and thymidine
- What is the mechanism of action for Cisplatin?
- alkylation of DNA
- What spp. do we never want to use cisplatin for?
- cats
- How do you prevent nephrotoxicity in dogs when administering cisplatin?
- pre hydrate the animal with saline to keep the kidney going
- What side effects can be seen with Cisplatin treatment?
- vomition, anorexia, and nausea
- What drug(s) do you want to pretreat the animal with if Cisplatin must be administered?
- butorphenol or ondansetron
- What clinical signs may be seen with repeated doses of Cisplatin treatment?
- hypomagnesemia, hypocalcemia, hyponatremia, hypokalemia, and hypophosphatemia
- What drug is most similar to Cisplatin?
- Carboplatin
- What kind of needles are forbidden when giving platinum drugs?
- ammonium needles
- What is the difference between Carboplatin and Cisplatin?
- Carboplatin is safe to use in cats and is less renal toxic
- What agents is not recommended to give with carboplatin and cisplatin?
- aminoglycosides
- How can cisplatin and carboplatin be administered?
- intralesionally
- In what conditions is L-Asparaginase used?
- in lymphoid leukemia and lymphomia
- What precaution is taken with administration of L-Asparaginase?
- pretreat animal with diphenhydramine b/c this foregin protein can cause allergic reaction
- What drug is given concurrently with piroxicam(non-steroidal antiinflammatory agent with antitumor activity) to prevent GI ulceration?
- misoprostol