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Pharmacology Exam 2 > Sulfonamide Antimicrobial Agents > Flashcards

Sulfonamide Antimicrobial Agents Flashcards

1
Q

Activity of prontosil?

A

Inactive in vitro, prodrug in that its metabolites are active

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2
Q

Prontosil used to treat?

A

Candida albicans

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3
Q

What do sulfonamides competitively inhibit?

A

Incorporation of p-aminobenzoic acid into folic acid nucleus via inhibition of dihydropteroate synthase

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4
Q

Why do sulfonamides not hurt mammalian cells, but hurts bacterial cells?

A

Mammalian cells utilize preformed folate in the diet while bacterial cells make their own folic acid

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5
Q

Antibiotic activity of sulfonamides can be reversed by what?

A

Adding large quantities of PABA (p-aminobenzoic acid) to diet

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6
Q

Structure of sulfanilamide resembles what

A

PABA

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7
Q

Acidity of PABA vs sulfanilamide?

A

PABA pKa 6.5

Sulfanilamid pKa 10.4

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8
Q

What type of acid is sulfanilamide?

A

Weak acid

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9
Q

What enhanced the potency and acidified the sulfonamide nitrogen of sulfanilamide drug?

A

Attachment of electron withdrawing heteroaromatic rings

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10
Q

Increase in acidity decrease the incidence of what?

A

Crystalluria (Crystallization of the sulfonamide in urine resulting in kidney damage)

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11
Q

What do they recommend be done when taking sulfonamides to reduce crystalluria?

A

Drink large amounts of water

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12
Q

Sulfonamides in general inhibit what?

A

Gram + and Gram -
Nocardia
Chlamydia trachomatis
Protozoa/fungi

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13
Q

How are sulfonamides usually used in treatment?

A

In combination

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14
Q

Why are sulfonamides usually used in combination?

A

Resistance factors are too widespread

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15
Q

Most popular sulfonamide?

A

Sulfisoxazole

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16
Q

What are sulfisoxazole and sulfamethoxazole used to treat>

A

Urinary tract infections

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17
Q

What is used in a 1:1:1 ratio to treat Gardnerella vaginalis?

A

Sulfabenzamide, sulfacetamide, and sulfathiazole

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18
Q

What is sulfasalazine?

A

Prodrug not well absorbed from GI tract

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19
Q

What do bacteria metabolize sulfasalazine to?

A

Sulfapyridine and 5-aminosalicyclic acid

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20
Q

Function of 5-aminosalicyclic acid?

A

Antiinflammatory

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21
Q

What is sulfasalizine used to treat?

A

Ulcerative colitis and Chron’s disease

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22
Q

Why don’t we just administer 5-aminosalicyclic acid directly?

A

Irritating to gastric mucosa

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23
Q

Sulfadoxine and pyrimethamine are used together to prevent what?

A

Malaria

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24
Q

Pyrimethamine is inhibitor of what?

A

Plasmodium falciparum dihydrofolate preductase

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25
Q

First line chemotherapy to treat acute toxoplasmosis?

A

Sulfadiazine and pyrimethamine

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26
Q

How to sulfonamides and their derivatives interact?

A

Cross-allergenic

27
Q

Rare skin and mucous membrane rash that is potentially fatal due to sulfonamide interaction?

A

Stevens-Johnson syndrome

28
Q

Resistance to sulfonamides occurs through what mechanisms?

A

1) Mutations cause overproduction of PABA
2) Mutations in target enzyme (dihydropteroate synthase)
3) Mutations result in decrease of cell permeability to sulfonamides

29
Q

What has happened with trimethoprim and resistance?

A

Plasmid borne copy of dihydrofolate reductase gene decreases binding to enzyme

30
Q

How is Trimethoprim cleared?

A

Inactive metabolites cleared in urine

31
Q

What are sulfonamides metabolized by?

A

N-4 N-acetylation

N-1 glucuronidation

32
Q

Metabolites of sulfonamides are what when acetylated/glucuronidated?

A

Inactive

33
Q

Which metabolites of sulfonamides are toxic?

A

Hydroxylamine and nitroso

34
Q

Human population divided into what types of acetylators?

A

Rapid or slow

35
Q

First generation Quinolones good against what?

A

Gram -

36
Q

First generation QL only useful for what?

A

Lower urinary tract infections

37
Q

How is 2nd generation differ from 1st generation?

A

Fluorine at C-6
Heterocyclic ring at C-7
Broader spectrum and more potent

38
Q

what do 2nd generation QLs work on?

A

Gram -
Gram +
Mycoplasma

39
Q

Most potent fluoroquinolone?

A

Ciprofloxacin

40
Q

How do 3rd and 4th generation QL differ from 2nd?

A

Multiple fluorine atoms

Improved activity against Gram + (Strep pneumonia)

41
Q

Are 3rd/4th generation better than Ciprofloxacin for gram -?

A

No, Cipro still best

42
Q

What QL is known as “drug of last resort”?

A

Moxifloxacin

43
Q

Why is Moxifloxacin known as drug of last resort?

A

Sever side effects

44
Q

How many strands of DNA do Topoisomerases cuts?

A

Topoisomerase 1 cuts 1 and topoisomerase 2 cuts 2

45
Q

How do topoisomerase and gyrases cut DNA>

A

Nucelophillic attack on phosphodiester link

46
Q

How do QL work?

A

They inhibit relegation reaction which eventually leads to apoptosis/death

47
Q

Which topoisomerase type has been crystallized and had X-ray structures determined?

A

Type 2

48
Q

Most common use of QLs?

A

Urinary tract infections

49
Q

First line treatment of Neisseria Gonorrhoeae due to QL resistance?

A

Ceftriaxone

50
Q

Increased fluoroquinolone resistance rates correlated with what?

A

Use

51
Q

Spontaneously occuring point mutations where causes QL resistance?

A

A-subunit of DNA gyrase

52
Q

What does point mutation of gyrase A-subunit achieve?

A

Enzyme with altered binding affinity

53
Q

Fluoroquinolone penetration of Gram - bacteria dependent on what?

A

Diffusion through porin channels

54
Q

Under-dosing runs the risk of whaT?

A

Selecting for resistant organisms

55
Q

How are fluoroquinolone taken?

A

Orally, high bioavailability

56
Q

Renal and hepatic clearance are important for all QLs except which?

A

Oxafloxacin (95% renal)

57
Q

How long until QLs interstitial concentration exceed serum concentrations?

A

4-24 hours

58
Q

What do you want to avoid mixing with QLs?

A

Heavy metals/food drugs with heavy metals due to insoluble chelates

59
Q

Major inactive metabolite of QLs?

A

Glucuronide at 3 carboxyl position

60
Q

Most common adverse side effect of QLs?

A

Nausea, vomiting, and diarrhea

61
Q

Who do you not want to give QLs to?

A

Patients under 18 due to interference with growing cartilage

62
Q

What adverse effect can happen with lomefloxacin?

A

Photosensitivity

63
Q

Gatifloxacin associated with what?

A

Hyperglycemia and hypoglycemia in diabetic patients

Pharmacology Exam 2 (9 decks)

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