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Pharmacology -- Test #2 > Quinolone Antimicrobial Agents > Flashcards

Quinolone Antimicrobial Agents Flashcards

1
Q

Name the four quinolone core structures

A

Quinolone
Cinnolone
1,8-Naphthyridone
Pyridopyrimidone

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2
Q

First generation quinolones are used to treat

A

Gram Negative Bacteria

Only useful for lower urinary tract infections

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3
Q

Two examples of first generation quinolones?

A

Oxolinic acid

Nalidixic acid

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4
Q

Defining characteristics of second generation quinolones

A

Fluorine substituent at C6

Heterocyclic ring at C7

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5
Q

Three common examples of second generation quinolones

A

Norfloxacin
Ciprofloxacin
Levofloxcin

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6
Q

Second generation quinolones are much more effective against…

A

G- species (including Pseudomonas)

Extended activity against G+ organisms and mycoplasma

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7
Q

The most potent flouroquinolone

A

Ciprofloxacin

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8
Q

How are 3rd and 4th generation quinolones different from 2nd?

A

Multiple Fluorine atoms

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9
Q

3rd/4th Generation quinolones are more effective against…

A

G+ organisms (esp. strep pneumo)

None as good as Cipro against Gram negatives

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10
Q

Two examples of 3/4th generation quinolones

A

Sparfloxacin

Moxifloxacin

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11
Q

Moxifloxacin is considered a drug…

A

of last resort

Severe Side Effects

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12
Q

How do DNA topoisomerases and gyrases cleave DNA?

A

A Nucleophilic attack on a phosphodiester linkage

One strand becomes free, the other enzyme linked

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13
Q

The nucleophile targeted by DNA topiosomerases and gyrases?

A

the phenolic hydroxyl group of a tyrosine residue

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14
Q

Decribe the method of DNA transport by bacterial topoisomerases and gyrases?

A
  1. G-segment DNA binds a high affinity CAP region site
  2. CAP regions remain in closed conformation
  3. 2 ATP bind ATPase domains
  4. N gate closure with T seg trapped in the DNA capture domain
  5. G-sgement DNA gate opens, T seg passes through
  6. G-segment DNA religates. C-gate opens
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15
Q

G-segment binding requires what enzyme conformation

A

An open N gate and an opening between the two B regions of the protein
Once bound, the CAP regions remain closed

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16
Q

What is likely assoiciated with ATP hydrolysis of topiosomerases? Why?

A

A conformational change

To help squeeze the T segment through the open gate

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17
Q

How is the cycle of Topisomerase activity ended?

A

Rapid closure of the C gate

Release of hydrolysis products and open N gate

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18
Q

The dimeric enzyme binds _____ and cleaves the strands with ______

A

duplex DNA

A Four Base Stagger

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19
Q

Clevage involves covalent attachment of…

A

Each subunit of the dimer through a phosphotyrosine linkage to the 5’ end of the DNA

20
Q

When would the gyrase/topisomerase mechanism be used within the same molecule? From different ones?

A

Same – Relaxation, Knotting, Unknotting

Different – Catenation, Decatenation

21
Q

Requirements for topisomerase/gyrases to be active?

A

Mg++

ATP hydrolysis

22
Q

How is the phosphodiester backbone rejoined/ligated?

A

Nucleophliic Displacement of the Protein Tyrosine residue

23
Q

Quinolone antibiotics bind to…

A

the Cleavage complex that exists after a strand is broken

24
Q

What happens after the quinolone antibiotic has bound?

A

The clevage comlex is stabilized and the religation reaction is inhibited. This blocks progression of the replication fork and the DS breaks will lead to apoptosis.

25
Q

Most common therapeutic uses of quinolones?

Which ones?

A

UTIs

Norfloxacin, Ciprofloxacin, ofloxacin, and nalidixic acid

26
Q

Treatment for prostatitis?

A

Norfloxacin, Ciprofloxacin, Ofloxacin

27
Q

STDS treatable with quinolones?

A

Neisseria gonorrhoeae
Chlamydia
Ducreyi

28
Q

Treatments for gonorrhea and ducreyi?

A

Ciprofloxacin

29
Q

Treatments for Chlamydia?

A

Ofloxacin

Sparfloxacin

30
Q

First line treatment against gonorrhea

A

Ceftriaxone

Too much resistance to quinolones

31
Q

Quinolones can be used to treat what GI illness?

Which drugs?

A

Traveler’s Diarrhea, Reduces time for cholera

Norfloxacin, Ciprofloxacin, Ofloxacin

32
Q

Quinolones effective against Strep pneumo

A

Moxifloxacin

33
Q

______ as a sole therapy is effective in 50% of diabetic foot infections

A

Ciprofloxacin

34
Q

______ and ______ are effective against intracellular bacteria

A

Norfloxacin

Ciprofloxacin

35
Q

Fluoroquinolone resistance mechanisms include…

A

Decreased cellular permeability
Efflux Pumps
Mutation of the target enzymes

36
Q

Two specific types of mutations that might alter quinolone efficacy

A
  1. Mutation of a-subunit of DNA gyrase that inhibits binding affinity for the drug
  2. B-subunit mutations

Especially if these mutations are additive

37
Q

Floroquinolone penetration of G- bacteria depends on…

A

diffusion through porin channels

38
Q

Bioavailability of fluoroquinolones?

A

Readily absorbed orally

high bioavailability

39
Q

Which flurorquiolone isn’t dependent on renal and hepatic clearance?

A

Oxafloxacin (almost entirely renal)

40
Q

Quinolones should not be distributed with foods/drugs containing…

A

heavy metals

They form insoluble chelates

41
Q

The major inactive metabolite of quinolones

A

the glucuronide at the 3 carboxyl position

42
Q

Most common side effects of quinolones?

A

Nausea, Vomiting, and Diarrhea

43
Q

CNS reactions associated with quinolones?

A

Headache and Dizziness

Hallucinations, Delirium, Seizures

44
Q

Why don’t you give quinolones to patients under 18?

Exception?

A

Damage to growing cartilage, arthropathy

Exception - CF patients

45
Q

Photosensitivity has been reported with…

A

Lomefloxacin

46
Q

Uncontrolled sugar in diabetic patients is associated with…

A

Gatifloxacin

Pharmacology -- Test #2 (13 decks)

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