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Pharm Exam 2 > Antibiotics 5 - Sulfonamides and Quinolones > Flashcards

Antibiotics 5 - Sulfonamides and Quinolones Flashcards

1
Q

(sulfonamide) ______ was inactive in vitro

But this is a prodrug of the active ________

A

Prontosil

p-aminobenzenesulfonamide

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2
Q

Sulfanilamide (pharmacologically active) is used to treat ____ infections

A

Vaginal candida

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3
Q

MOA of sulfonamide antibiotics

A

Competitively inhibits the incorporation of PABA into folic acid

by inhibiting the enzyme dihydropteroate synthase

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4
Q

What reaction does dihydropteroate synthase catalyze?

What are the following steps in this pathway?

A

Dihydropteroate diphosphate -> Dihydropteroic acid

**next steps: conversion to DHF acid -> THF acid –> methyleneTHF acid –> Thymine –> DNA

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5
Q

Sulfonamides are bioisosteres of ____

A

PABA

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6
Q

There is a significant difference in ____ between PABA and sulfanilamide

What does this mean for the drug?

A

Acidity (pKa)

PABA = 6.5 Sulfanilamide = 10.4

This causes sulfanilamide to be 1000x more neutral as a drug

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7
Q

What two effects does attaching electron-withdrawing heteroaromatic rings to the sulfonamide nitrogen?

A

Increases ACIDITY = increased stability = increased potency**

This also decreases crystalluria in the urine

**essentially makes it more similar to the normal metabolite

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8
Q

Sulfonamides in general inhibit…

A
  • Gram + and -
  • Nocardia
  • Chlamydia trachomatis
  • Enterics (e.coli, kleb, salmonella, shig, enterobact)
  • some protozoa and fungi
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9
Q

Sulfamethoxazole combined with ____ is important for treatment of _______

A

Trimethoprim

PCP (in aids)

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10
Q

Trimethoprim inhibits _____

A

Dihydrofolate reductase

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11
Q

Most common sulfa

A

Sulfisoxazole

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12
Q

sulfisoxazole and sulfamethoxazole are mainly used to treat ________

A

uncomplicated UTI

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13
Q

What is triple sulfa and what does it treat?

A

1:1:1 mix of -benzamide, -acetamide, -thiazole

Treatment of Gardnerella vaginalis

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14
Q

Sulfasalazine is a____ that is not…

What is the metabolism?

A

prodrug, …not absorbed well in GIT

**metabolized to sulfapyridine and 5-aminosalicylic acid

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15
Q

Long acting sulfonamide

A

Sulfadoxine

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16
Q

Sulfadoxine is used with _____ to treat _____

A

pyrimethamine

malaria

(pyrimethamine inhibits DHFR in p. falciparum)

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17
Q

Sulfadiazine is used with _____ to treat _____

A

pyrimethamine

Toxoplasma gondii

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18
Q

Sulfonamide derivative examples (3)

A
  1. Carbonic anhydrase inhibitors (acetazolamide)
  2. Thiazides (HCTZ)
  3. Hypoglycemic agents (tolbutamide)
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19
Q

Most commone AE’s of sulfonamides (6)

A
  1. Rash
  2. Photosensitivity
  3. Drug fever
  4. Stevens-Johnson syndrome
  5. Crystalluria
  6. Hematopoietic disturbances (HA, AA, Granul, Thromb)
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20
Q

What three mutations can cause resistance to sulfonamides

A

Overproduction of PABA

Dihydropteroate synthase

Decrease in cell permeability

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21
Q

Bactrim composition

A

400mg SMX

80mg TMP

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22
Q

PK of TMP compared to SMX

A

absorbed 85=90%

distributed more rapidly than SMX

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23
Q

SMX distribution and clearance (description)

A

wide distribution

rapid clearance

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24
Q

Why isnt SMX as widely distributed as TMP

A

Differences in lipophilicity

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25
Q

Tissue ratio of SMX:TMP

A

1:2 to 1:5

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26
Q

Short half life sulfas

A

Soxazole

methizole

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27
Q

Intermediate half life sulfas

A

Diazine

methoxazole

28
Q

Sulfa metabolism mechanism

A

VIa N-4 N-acetylation

(in some cases N-1 glucuronidation)

29
Q

Toxic metabolites of sulfa

A

Hydroxylamine and nitroso metabolites

30
Q

First gen Quinolones have limited ___ activity

A

G+

31
Q

FIrst gen quinolones are only useful for

A

lower UTIs

32
Q

Two examples of First gen quinolones

A

Nalidixic Acid

Oxolinic acid

33
Q

Second gen quinolone structure difference

A

Fluuorine ata C6

Heterocyclic ring (usually piperazine) at C7

34
Q

Norfloxacin and levofloxacin shows a 40-100x poteny over nalidixic acid against…

A

most gram negatives incl. pseudomonas

35
Q

Second gen quinolones have an extended activity against

A

G+ and mycoplasma

36
Q

3rd and 4th gen quinolones often have _____

A

multiple Fluorine atoms

37
Q

Best 3rd/4th gen for G-

A

Ciprofloxacin

38
Q

Which quinolone is a last resort?

A

Moxi

39
Q

topoisomerases (TI) and gyrases cleave DNA by …

A

carrying out nucleophilic attack on a phosphodiester linkage

–> one strand is free and one is enzyme linked

40
Q

Nucleophile used by TI/gyrase

A

phenolic OH group of Tyrosine

41
Q

TI-catalyzed reaction is _____

The equilibrium tends to favor…

A

Reversible

in favor of the uncleaved DNA

42
Q

Most common use for quinolones

A

UTI

43
Q

Second and Third most common use for quinolones

A

Prostatitis

STD

44
Q

Chlamydia trachomatis quinolones

A

ofloxacin + sparfloxacin

45
Q

quinolone for N gonorrheae and H. ducreyi

A

Ciprofloxacin

46
Q

First line for gonorrhea

A

ceftriaxone

47
Q

Fourth and Fifth use for quinolones

A

GI

Respiratory Tract Infections

48
Q

Shigellosis quinolones

A

Nor

Cipro

O

49
Q

Which quinolones WONT treat Bone, join, and soft tissue infections

A

Norfloxacin

50
Q

____ is 50% effective as monotherapy in diabetic foot infections

A

Cipro

51
Q

Quinolones that have use against intraellular bacteria

A

Nor

Cipro

52
Q

Resistant organisms (to quinolones) have spontaneously occurring point utations in…

A

the A-subunit of DNA gyrase

(results in a 16-fold increase in MBC for fluoroquinolones)

53
Q

Less common mutation for quinolone resistance

A

the B subunit of DNA gyrase

(results in a lower level of resistance)

54
Q

Penetration of quinolone to gram negative bacteria is dependen on…

A

diffusion through porin channels (esp in E. coli and pseuomonas)

55
Q

____ should be avoided when giving quinolones

A

Under-dosing

56
Q

Quinolones high or low oral BA?

Wide or narrow distribution?

A

High oral BA

Wide distribution

57
Q

Route of clearance for all quinolones (with one exception)

A

Renal and hepatic

(oxafloxacin is 95% renal)

58
Q

Interstitial fluid concentrations __________ from 4-24 hours

A

Exceed serum concentrations

59
Q

Quinolones form insoluble chelates with ______

A

heavy metals

60
Q

Major inactive metabolite is the ______

A

glucuronide at the 3 carboxyl position

excreted in the urine

61
Q

Most common AE for quinolones

A

N/V/D

62
Q

Hallucinations and delirium an occur in patients who are also taking…

A

Theophylline

NSAID

63
Q

Quinolones are associated wih ____ (as an AE)

A

peripheral neuropathy

64
Q

Why shouldnt you give quinolones to kids?

A

May damage growing cartilage and cause arthropathy (reversible)

65
Q

Lomefloxacin AE

A

Photosensitivity

66
Q

Gatifloxacin AE

A

Hyper/Hypoglycemia in diabetic patients

67
Q

Exception to the “dont give to kids” rule for quinolones

A

Pseudomonal infections in kids with CF

(High mortality rate, benefits>risks)

Pharm Exam 2 (12 decks)

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