Overview of Exam 2

Question 1

In transcription of DNA, what is the strand that is copied?

Answer 1

Noncoding (antisense) strand

Question 2

Function of the 50S subunit of bacterial ribosomes

Answer 2

Biochemical tasks (does the actual synthesis of the new protein)

Question 3

Function of the 30S subunit of bacterial ribosomes

Answer 3

Has to do with binding (and recognition of molecules and reading the code)

Question 4

Peptidyl transferase

Answer 4

actual enzyme in the ribosome that has the catalytic activity to form the peptide bond

Question 5

MOA of Aminoglycosides

Answer 5

1.) Interferes with initiation (where ribosome finds AUG start codon)
2.) Premature termination
3.) Causes wrong AA to be put in place
**Secondary action= might directly affect membrane permeability
BACTERIOCIDAL

Question 6

Post-antibiotic effect

Answer 6

bacteria continue to die even after antibiotics have been stopped (residual antibiotic activity)

Question 7

What’s special about doxycycline?

Answer 7

Only TC that can be dosed once/day (longer t1/2); is the only TC that covers CA-MRSA (not HA-MRSA)

Question 8

What’s special about minocycline?

Answer 8

Can go over CSF since it is the most lipophilic of the tetracyclines; causes bluish-black pigmentation to skin in some pts; causes ototoxicity

Question 9

MOA of tetracyclines

Answer 9

Bind to A site of 30S and blocks access of tRNA

BACTERIOSTATIC

Question 10

What TC’s can you use in renal compromise?

Answer 10

Minocycline or Doxycycline

Question 11

Important ADR’s of Tetracyclines

Answer 11

Teeth discoloration and bone effects!, Hepatotox, Nephrotox, Benign Intracranial hypertension (edema in the brain), Fanconi Syndrome (so don’t “save” you pills!)

Question 12

MOA of Glycylcyclines

Answer 12

Blocks entry into A site of 30S (like TC’s) but are not affected by resistance mechanisms like TC’s are

Question 13

Important ADR’s of Glycylcyclines

Answer 13

Teeth discoloration and bone effects (from chelation of metal); < elimination of Warfarin

Question 14

MOA of Macrolides

Answer 14

Block the exit tunnel (DOES NOT INHIBIT RIBOZYME DIRECTLY)

Question 15

Important ADR’s of Macrolides

Answer 15

Epidgastric distress, ototoxicity, cholestatic jaundice, metallic taste (only in Clarithro), Q-T prolongation/ torsades, 3A4 drug interactions

Question 16

MOA of Telithromycin

Answer 16

Binds to 50S on 2 separate areas (exit tunnel like macrolides & other site nearby on 50S)

Question 17

Important ADR’s of Telithromycin

Answer 17

Syncope (fainting), CYP interactions, Q-T prolongation, torsades

Question 18

MOA of Lincosamides

Answer 18

Bind to exit tunnel of 50S and cause backlog

Question 19

Important ADR’s of Clindamycin

Answer 19

Pseudomembranous Colitis (overgrowth of C. diff), > liver enzymes, < neurotransmission

Question 20

MOA of Streptogramins

Answer 20

A binds to allosteric site on 50S and B binds to exit tunnel (same site as macrolides)

Question 21

Important ADR’s of Streptogramins

Answer 21

CYP 3A4 interactions, arthralgia/myalgia

Question 22

MOA of Chloramphenicol

Answer 22

Prodrug –> Inhibits peptidyl transferase (inhibits binding of tRNA to ribosome and prevents actual peptide bond from being made)

Question 23

Important ADR’s of Chloramphenicol

Answer 23

Mostly related to the fact that human protein synthesis in mitochondria can also be inhibited: Bone marrow suppression, aplastic anemia, Gray Baby Syndrome

Question 24

MOA of Oxazolidinones

Answer 24

Prevents initiation and not elongation!! (means no cross resistance with other abx) Binds to 50S and prevents 50S from coming into contact with 30S to form initiation complex

Question 25

Important ADR's of Linezolid

Answer 25

Myelosuppression, Pseudomembranous Colitis, ** Linezolid is a weak inhibitor of MAO so can also have enhanced effects of adrenergic agents that use this enzyme: Serotonin Syndrome (when administered with SSRI's), Cheese Reaction (avoid food or drink high in tyramine)

Question 26

MOA of Quinolones (Fluoroquinolones)

Answer 26

``` Inhibit topoisomerases= allows them to break the DNA but then binds and prevents them from re-sealing the nick DNA gyrase (Topoisomerase II)= Gram (-) Topoisomerase IV= Gram (+) ```

Question 27

Important ADR's of FQ's

Answer 27

Achilles and Rotator Cuff Tendonitis and Rupture, Q-T prolongation/ torsades, CYP inhibition, chelation

Question 28

Which FQ can you use in renal failure?

Answer 28

Moxifloxacin (since it is most excreted by liver)

Question 29

MOA of Nitrofurantoin

Answer 29

Gets activated by having its NO2 group reduced by NADPH --> attacks sensitive enzymes

Question 30

Important ADR's for Nitrofurantoin

Answer 30

``` Hemolytic anemia (in pts with G6PD deficiency) Acute pneumonitis (if drug achieves tx conc in blood) ```

Question 31

MOA for Metronidazole

Answer 31

PRODRUG --> activated when NO2 group is reduced by electron transport chain (ferrodoxins) --> attacks DNA

Question 32

Important ADR's for Metronidazole

Answer 32

Furry tongue/ metallic taste, Steven-Johnson's Syndrome, Disulfiram-like effect (if you drink you become ill) NO PREGO!

Question 33

MOA of Rifamycins

Answer 33

Inhibit RNA Polymerase (transcription initiation)

Question 34

Important ADR's of Rifamycins

Answer 34

Red-orange color to body fluids, induction of P450

Question 35

ADR's specific to Rifabutin

Answer 35

Polymyalgia, pseudojaundice, Anterior uveitis (inflammation of undercoating of eye)

Question 36

MOA of Sulfonamides

Answer 36

Act like PABA and inhibit dihydropterate synthase --> inhibit synthesis of folic acid (used in DNA synthesis)

Question 37

Important ADR's of sulfonamides

Answer 37

Crystalluria, hemolytic anemia (in pts with G6PD deficiency), SJS

Question 38

MOA of Trimethoprim

Answer 38

Inhibits dihydrofolate reductase (DHFR)

Question 39

Bactrim

Answer 39

Trimethoprim/ sulfamethoxazole 5:1 ratio

Question 40

Important ADR's for Trimethoprim

Answer 40

Megaloblastic anemia, hemolytic anemia (in pts with G6PD deficiency), jaundice

Question 41

MOA of Fidaxomycin

Answer 41

same as Rifamycins, bind to RNA Pol and prevent initiation of transcription

Question 42

MOA of Daptomycin

Answer 42

Needs calcium as a cofactor!; forms channels that leak ions

Question 43

Can Daptomycin be used in Respiratory infections?

Answer 43

NO! b/c the surfactants in the lungs soak up the drug

Question 44

Important ADR's with Daptomycin

Answer 44

Eosinophilic pneumonia, reversible myopathy, peripheral NS disorders

Question 45

MOA of polymixins

Answer 45

causes "leaks" in the membrane

Question 46

Important ADR's with Polymixins

Answer 46

Neurotox, Nephrotox

Question 47

MOA of Glycopeptides

Answer 47

Inhibit polymerization of cell wall by binding directly to D-Ala/D-Ala and blocking addition of new NAG-NAM

Question 48

Important ADR's of Glycopeptides

Answer 48

REDMAN'S SYNDROME, ototoxicity, nephrotoxicity, Q-T prolongation, NO PREGO