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Flashcards in L30 - Drugs Deck (28):
1

Name the 2 drugs that block folate synthesis

Sulfonamides
Trimethoprim
TMP-SMX combo

2

What enzyme do sulfonamides target?

Dihydro-pteroate synthetase
We don't have this enzyme so no side-effects to humans in taking this

3

What enzymes does trimethoprim target?

Dihydrofolate reductase
Drug has MUCH higher affinity for the bacterial version of this enzyme - small side effects for humans

4

Sulfonamides are rarely used alone. What are they given with? Why?

Trimethoprim + sulfamethoxazole (TMP-SMX)
- Enhanced activity via synergy
- Broad spectrum bactericidal action
- Less resistance

5

TMP-SMX use

Gram -
S. aureus (g+)
Some protozoa & fungi
Pseudo & enterococci resistant
* Urinary, respiratory, GI infections*

6

How are folate antagonists given

Oral/IV

7

What are the adverse effects for folate antagonists

Rash, GI = common
Severe:
- SJS
- Toxic epidermal necrolysis
- Amenias and thrombocytopenia

8

What can happen with TMP-SMX during pregnancy?

Kernicterus = high bilirubin
Brain dysfxn in the baby

9

Trimethoprim resistance

Plasmid w/ dhfr gene
Transposon (Tn7) of integrons

10

Sulfonamide resistance

Plasmid that made TMP resistance/changes coding of dihydropteroate synthetase
Chromosomal mutation

11

What are the 3 DNA inhibitors

Quinolones
Furoquinolones
Nitrofurantoin

12

Quinolones mechanism

Double strand breaks to stabalizes topo-DNA complex
No DNA replication or RNA transcription
Chromosome fragmentation --> bactericidal (!)

13

What are quinolones used against

Gram - by inhibiting topo2
Gram + by inhibiting topo4
Atypicals & mycobacteria

14

How are quinolones given?

Oral
BUT poor absorption w/ divalent cations

15

Drug primarily targets topo2 and has good [ ] in urine. Not gets vs Step

Ciprofloxacin

16

Drug primarily targets topo4 and good vs Step

Levofloxacin

17

Quniolone that has strong g + and anaerobic activity

Moxifloxacin

18

What causes fluroquinolone resistance

gyrA or parC mutations
Efflux pumps

19

Quinolone adverse effects

Prolonged OT
Tendon rupture

20

What quinolone are you using to treat UTIs

Nitrofurantoin
Good against gram-/+ uropathogens
PO - poor serum but good urine [ ]
Might see nausea & pulm fibrosis

21

What are the 2 RNA inhibitors?

Rifamycins
Fidaxomicin

22

Rifamycin mechanism

Binds B subunit of RNA polymerase
X transcription
BacterioSTATIC

23

Rifamycin metabolism. What are the 3 forms of rifamycin?

Cp450 3A4 metabolism
Rifampin - induces this enzymes
Rifabutin
Rifaximin - not absorbed so for GI infections

24

Rifamycin use

In combos!
Prophylasis of N.meningitidis & S.aureus
GI as rifaximin - traveler's diarrhea

25

Rifamycin adverse effect

Hepatitis

26

Fidaxomicin mechanism

No open DNA complex --> X RNA polymerase
Non-absorbable!

27

Fidaxomicin use

C.diff!

28

Rifamycin and fidaxomicin is given...

PO