USMLE step 3 - drug MOA (indications)
Erythromycin - Answer-50S ribosome, inhibits TRANSLOCATION (movement of
tRNA-aa from acceptor site to peptidyl site)
clindamycin, chloramphenicol - Answer-50 ribosome, inhibits PEPTIDYL
TRANSFERASE (incorporation of new a.a.'s into growing strand)
linezolid - Answer-50S protein synthesis inhibitor
tetracycline - Answer-30S ribosome, blocks tRNA-aa from binding to ACCEPTOR
SITE on mRNA
aminoglycosides - Answer-30S ribosome, blocks INITIATION of translation and
induces PREMATURE TERMINATION or mistranslation
vancomycin - Answer-binds D-ala-D-ala portion of cell wall precursors, prevents
POLYMERIZATION OF PEPTIDOGLYCANS
cephalosporins - Answer-beta-lactam, with with some resistance to penicillinase
ampicillin, amoxicillin - Answer-beta-lactam, broader spectrum but still susceptible to
penicillinase
ticarcillin, piperacillin - Answer-beta-lactam, broad-spectrum
rifampin - Answer-blocks mRNA transcription by inhibiting mRNA POLYMERASE
beta subunit
metronidazole - Answer-interacts with microbial ferredoxins to produce CYTOTOXIC
INTERMEDIATES
fluoroquinolones - Answer-inhibits DNA GYRASE (controls supercoiling) and
TOPOISOMERASE (untangling interlocked daughter chromosomes)
trimethroprim - Answer-inhibits DIHYDROFOLATE REDUCTASE --> decreased
syntesis of thymidylate, purine nucleotides, amino acids
penicillin (beta-lactam) - Answer-1) bind PBPs
2) block TRANSPEPTIDASE cross-linking of peptidoglycan
3) activate AUTOLYTIC ENZYMES
clavalunic acid, sulbactam, tazobactam - Answer-beta-lactamase inhibitors
statins - Answer-HMGCoA REDUCTASE inhibitor -->decreased hepatic cholesterol
synth --> increased LDL receptor expression --> dec LDL
Erythromycin - Answer-50S ribosome, inhibits TRANSLOCATION (movement of
tRNA-aa from acceptor site to peptidyl site)
clindamycin, chloramphenicol - Answer-50 ribosome, inhibits PEPTIDYL
TRANSFERASE (incorporation of new a.a.'s into growing strand)
linezolid - Answer-50S protein synthesis inhibitor
tetracycline - Answer-30S ribosome, blocks tRNA-aa from binding to ACCEPTOR
SITE on mRNA
aminoglycosides - Answer-30S ribosome, blocks INITIATION of translation and
induces PREMATURE TERMINATION or mistranslation
vancomycin - Answer-binds D-ala-D-ala portion of cell wall precursors, prevents
POLYMERIZATION OF PEPTIDOGLYCANS
cephalosporins - Answer-beta-lactam, with with some resistance to penicillinase
ampicillin, amoxicillin - Answer-beta-lactam, broader spectrum but still susceptible to
penicillinase
ticarcillin, piperacillin - Answer-beta-lactam, broad-spectrum
rifampin - Answer-blocks mRNA transcription by inhibiting mRNA POLYMERASE
beta subunit
metronidazole - Answer-interacts with microbial ferredoxins to produce CYTOTOXIC
INTERMEDIATES
fluoroquinolones - Answer-inhibits DNA GYRASE (controls supercoiling) and
TOPOISOMERASE (untangling interlocked daughter chromosomes)
trimethroprim - Answer-inhibits DIHYDROFOLATE REDUCTASE --> decreased
syntesis of thymidylate, purine nucleotides, amino acids
penicillin (beta-lactam) - Answer-1) bind PBPs
2) block TRANSPEPTIDASE cross-linking of peptidoglycan
3) activate AUTOLYTIC ENZYMES
clavalunic acid, sulbactam, tazobactam - Answer-beta-lactamase inhibitors
statins - Answer-HMGCoA REDUCTASE inhibitor -->decreased hepatic cholesterol
synth --> increased LDL receptor expression --> dec LDL
