Antimetabolites Flashcards
antimetabolites destroy cells during what phase of the cell cycle
S phase- when DNA is synthesized
poorly lipid soluble folate analogue refers to which medication (folic acid antagonist)
methotrexate
what enzyme does methotrexate inhibit
dihydrofolate reductase
what form is methotrexate administerad
oral
what is methotrexate used for in children but not adults
acute lymphoblastic leukemia in children but not adults
other uses of methotrexate
rheumatoid arthritis
psoriasis
what three ways do resistance to methotrexate develop
impaired transport into cells
production of altered forms of dihydrofolate reductase (lacking affinity to the drug)
increased concentrations of intracellular dihydrofolate reductase
what are the most important side effects of methotrexate
GI- ulcerative stomatitis and diarrhea
bone marrow suppression -leukopenia and thrombocytopenia
what does the methotrexate pulmonary toxicity take form as
fulminant non cariogenic pulmonary edema
or
more progressive inflammation with interstitial infiltrates and pleural effusions
what should we measure preoperatively if the patient has had recent methotrexate
liver enzymes
what is the rescue technique used for methotrexate
protecting normal cells from lethal damage by folate antagonist by administration of folinic acid (leucovorin), thymidine, or both
how does fluorouracil work
by blocking production of thymine nucleotide by inhibiting thymidlyate synthase
T/F
flurouracil readily enters the CSF
True
clinical uses of fluorouracil
breast Ca, GI ca, keratoses of the skin and superficial basal cell carcinoma
this can occur up to one week after administration of fluorouracil
MI
what is the early warning sign of fluorouracil toxicity
stomatitis manifesting as a white patchy membrane that ulcerates and becomes necrotic - may warn of similar lesions in the esophagus and GI tract
what occurs 9-14 days following therapy and is a serious side effect of fluorouracil
myelosuppression manifesting as leukopenia and thrombocytopenia
what is capecitabine metabolized to, why do we administer capecitabine
metabolized to fluorouracil and has the potential to be more selective than fluorouracil (breast ca)
what is pemetrexed used for
mesothelioma and lung ca
cytarabine clinical use
acute leukemia in children and adults
side effects of cytarabine at high doses
cerebellar toxicity and ataxia can occur at high doses
what is gemcitabine used for
pancreas ca
breast ca
lung ca
common side effects of gemcitabine
bone marrow suppression flulike symptoms fever fatigue mild nausea and vomiting diarrhea
mercaptopurine is incorporated into DNA or RNA strands how does it work
block further strand synthesis or causes structural alterations that damage DNA
