Chemotherapy and antineoplastics Flashcards
What are your folic acid analagoues?
Methotrexate
What the pyrimidine analagoues?
5-Fluorouracil
Cytidine analogues?
cladribine, azacitidine, decitabine, gemcitabine
purine analogues?
6-thiopurine analagoues
What is an antimetabolite?
substance that competes with repplaces or inhibits a specific metabolite-intereferes with normal cell metabolic functioning
Antimetabolites MOA:
competititve inhibition-halts cell growth and cell division
intereferes with DNA synthesis and cellular function
Folate is known as?
Vitamin B 9
Folic acid is converted to? (active form)
tetrahydrofolate (FH4)
FH4 does what?
methyl group donor (reducing folic acid) for the synthesis of thymidine
Folic acid analogues MOA?
block the formation of thymidine—>purine nucleotide imbalance, ultimately slowing DNA synthesis
Methotrexate MOA
directly inhibits folate-dependent enzymes of de novo purine synthesis and thymidylate synthesis
MTX intereferes with ______ and inhibits ________
FH4 metabolism
inhibits DNA replication
Folate antagonists kill during which phase of the cell cylce>
S phase (most effective when cells proliferate rapidly)
Can terminate toxic effects of MTX using?
Leucovorin (repletes FH4 cofactors)
Leucovorin MOA?
converts into FH4 and bypasses the inhibition of DHFR by MTX
Folic acid analogues are?
polar-poorly crosses the BBB
Need: folate receptor, transporter that is active in low PH, and a reduced folate transporter
MTX inside cell» enzyme folylpolyglutamate synthesase (FPGS) does what?
adds additional glutamyl residues
polyglutamation serves as>
mechanism for ion trapping within cell, prolonged retention of MTX, and greater affinity
MTX-PGs constitute?
intracellular storage forms of folates and folate analogues that increase inhibitory potency of Thymidylate synthase (TS).
Resistance to antifolates?
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