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Pharmacology -- Test #2 > Sulfonamide Antimicrobials > Flashcards

Sulfonamide Antimicrobials Flashcards

1
Q

The first drug discovered to be effective against bacterial infections

A

Prostosil

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2
Q

What type of drug is Prostosil?

A

Prodrug

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3
Q

Prostosil is converted to…

A

p-aminobenzenesulfonamide

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4
Q

What p-aminobenzenesulfonamide (Sulfanilamide) used to treat?

A

Vaginal Candida albicans

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5
Q

What is PABA?

A

p-aminobenzoic acid

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6
Q

PABA is incorporated into ______ in the process of making _____

A

Folic Acid Nucleus

Thymine (DNA)

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7
Q

Step in thymine synthesis inhibited by Sulfonamides?

How?

A

Incorporation of PABA

Inhibition of Dihydropteroate Synthase

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8
Q

Why don’t sulfonamides mess up human DNA synthesis?

A

Mamallian cells primarily utilize folates in the diet

Bacteria have to make their own

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9
Q

Type of inhibition seen in sulfonamides?

A

Competitive

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10
Q

Aside from inhibition of Dihydropteroate Synthase, how might sulfonamides act as antimicrobials

A

Some strains of bacteria use sulfonamides as a substrate, but the product is not capable of undergoing the next reaction

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11
Q

How do you reverse sulfonamides?

A

Add in large quantities of PABA

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12
Q

Difference in the acidity of PABA ad sulfanilamide

A

PABA - 6.5

Sulfonalimide - 10.4

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13
Q

Difference in the structure of PABA and sulfanilamide

A

PABA – ends with COOH

Sulfanilamide – SO2NR2

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14
Q

PABA is mainly ________ at physiologic pH

Sulfanilamide is mainly ___________

A

PABA – Anionic

Sulfanilamide – a Weak Acid

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15
Q

How did early work reveal that sulfonamide derivatives could be made more potent

A

By attaching electron-withdrawing heteroaromatic rings

This acidified the sulfonamide nitrogen

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16
Q

Why does attaching the aromatic ring to a sulfonamide derivative cause it to become more acidic?

A

Electronegativity of the aromatic substituients

Resonance stabilization of the anion

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17
Q

Side effects influences by increasing the acidity of Sulfanilamines?

A

Decreased incidence of crystalluria

which is sulfonamide crystallization in the urine resulting in kidney damage

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18
Q

Name the 9 clinically used sulfonamides

A 
Sulfisoxazole
Sulfimethizole
Sulfacetamide
Sulfmethoxazole
Sulfabenzamide
Sulfathiazole
Sulfadiazine
Acetyl Sulfisoxazole
Sulfasalizine
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19
Q

Clinical targets of sulfonamides?

A

G+ and G-
Nocardia, Chlamydia
Some protazoa and fungi
Enteric bacteria

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20
Q

Why are sulfonamides usually used in combinations?

A

Too many resistance factors for these drugs

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21
Q

Most common sulfonamide combination therapy

A

Trimthoprim-Sulfamethoxazone

Bactrim

22
Q

What is Bactrim

A

Trimethoprim (80mg) -Sulfamethoxazole (400mg)

23
Q

What does trimethoprim do?

A

Inhibits dihydrofolate reductase

24
Q

How to trimathoprim and sulfamethoxazole complement one another?

A

The combination inhibits two sequential steps in the biosynthesis of tetrahydrofolic acid

25
Q

Trimethoprim-sulfamethoxazole is a common treatment for…

A

AIDS patients with Penumocystis jiroveci

26
Q

The most popular sulfonamide?

A

Sulfisoxazole

27
Q

Sulfisoxazole and sulfamethoxazole are mainly used for…

A

UTIs

28
Q

Combination of Sulfa drugs used to treat Gardnerella vaginalis

A

Sulfabenzamide
Sulfacetamide
Sulfathiazole

Triple Sulfas

29
Q

Why take a triple sulfas-phenylpropanolamine-pheniramine?

A

Used orally or in suspension form

Treat sinus and throat infections

30
Q

What is sulfasalazine?

A

A prodrug with poor GI absorption

31
Q

Bacteria in the GI tract metabolize sulfasalazine into…

A

Sulfapyridine and 5-aminosalicyclic acid (an anti-inflammatory)

32
Q

What is Sulfasalazine used to treat?

A

Ulcerative Colitis

Crohn’s Disease

33
Q

Problem with directly administering Salicyclates?

A

Irritation to the gastric mucosa

34
Q

What is sulfadoxine? What is it used to treat?

A

A long-acting sulfonamide used with pyrimethamine to prevent and treat malaria

35
Q

What does pyrimethamine do?

A

It is an inhibitor of falciparum hihydrofolate reductase

36
Q

Name for the combination of sulfadoxine and pyrimethamine?

A

Fansidar

37
Q

What is sulfadiazine used to treat?

A

Used w/ pyrimethamine as first line chemo to treat acute Toxoplasmosis

38
Q

Adverse reaction of all sulfonamides and their derivatives

A

Cross-Allergenic
Crystalluria
Hematopoetic disturbances

39
Q

Examples of sulfonamide derivatives

A

Carbonic anhydrase inhibitors
Thiazides
Furosemide
Sulfonylurea hypoglycemic agents

40
Q

Ways a sulfonamide allergic reaction may present

A

Rash, Photosensitivity, Drug Fever
Stevens-Johnson syndrome
Rarely, anorexia, nausea, vomiting

41
Q

What is Stevens-Johnson syndrome?

A

A rare sulfa drug allergic response resulting in a potentially fatal skin and MM rash

42
Q

Hematopoetic disturbances associate with sulfa drugs

A

Hemolytic or aplastic anemia
Granulocytopenia
Thrombocytopenia

43
Q

Three mechanisms for sulfonamide resistance…

A
  1. Mutations causing PABA overproduction
  2. Mutations in the dihydroperoate synthase that decrease affinity
  3. Mutations that decrease cell permeability to sulfonamides
44
Q

Resistance to trimethoprim is indicated by…

A

DHFR gene

45
Q

What does the DHFR gene do?

A

Enables the expressed enzyme to be active in the presence of drug through a decreased binding affinity of trimethoprim

46
Q

Why is trimethoprim so much of a smaller component of bactrim?

A

TMP is absorbed at (85-90%) and distributed much faster than sulfonamides

47
Q

How is trimethoprim cleared

A

The drug and its oxidized metabolites are cleared in the urine

48
Q

Sulfamethoxalone (SMX) distribution through body

A 
Widely distributed (including CSF)
Rapidly eliminated
49
Q

Half life of TMP and SMX

A

about 10-12 hours

50
Q

TMP or SMX, who is more widely distributed

A

TMP (because its more lipophilic)

Preferential distribution of tmp to tissues

51
Q

How are sulfonamides metabolized?

A

N-4 acetylation and sometimes N-1 glucaronidation

Pharmacology -- Test #2 (13 decks)

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