Antibiotics 5 - Sulfonamides and Quinolones Flashcards Preview

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Flashcards in Antibiotics 5 - Sulfonamides and Quinolones Deck (67)
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1

(sulfonamide) ______ was inactive in vitro

 

But this is a prodrug of the active ________

Prontosil

 

p-aminobenzenesulfonamide

2

Sulfanilamide (pharmacologically active) is used to treat ____ infections

Vaginal candida

3

MOA of sulfonamide antibiotics

Competitively inhibits the incorporation of PABA into folic acid

 

by inhibiting the enzyme dihydropteroate synthase

4

What reaction does dihydropteroate synthase catalyze?

 

What are the following steps in this pathway?

Dihydropteroate diphosphate -> Dihydropteroic acid

 

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

5

Sulfonamides are bioisosteres of ____

PABA

6

There is a significant difference in ____ between PABA and sulfanilamide

 

What does this mean for the drug?

Acidity  (pKa)

PABA = 6.5   Sulfanilamide = 10.4

 

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

7

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

Increases ACIDITY = increased stability = increased potency**

This also decreases crystalluria in the urine

 

**essentially makes it more similar to the normal metabolite

8

Sulfonamides in general inhibit...

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

9

Sulfamethoxazole combined with ____ is important for treatment of _______

Trimethoprim

PCP (in aids)

10

Trimethoprim inhibits _____

Dihydrofolate reductase

11

Most common sulfa

Sulfisoxazole

12

sulfisoxazole and sulfamethoxazole are mainly used to treat ________

uncomplicated UTI

13

What is triple sulfa and what does it treat?

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

 

Treatment of Gardnerella vaginalis

14

Sulfasalazine is a____ that is not...

 

What is the metabolism?

prodrug,  ...not absorbed well in GIT

 

**metabolized to sulfapyridine and 5-aminosalicylic acid

15

Long acting sulfonamide

Sulfadoxine

16

Sulfadoxine is used with _____ to treat _____

pyrimethamine

malaria

 

(pyrimethamine inhibits DHFR in p. falciparum)

17

Sulfadiazine is used with _____ to treat _____

pyrimethamine

Toxoplasma gondii

18

Sulfonamide derivative examples (3)

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

19

Most commone AE's of sulfonamides (6)

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

20

What three mutations can cause resistance to sulfonamides

Overproduction of PABA

Dihydropteroate synthase

Decrease in cell permeability

21

Bactrim composition

400mg SMX

80mg TMP

22

PK of TMP compared to SMX

absorbed 85=90%

distributed more rapidly than SMX

23

SMX distribution and clearance (description)

wide distribution

rapid clearance

 

24

Why isnt SMX as widely distributed as TMP

Differences in lipophilicity

25

Tissue ratio of SMX:TMP

1:2 to 1:5

26

Short half life sulfas

Soxazole

methizole

27

Intermediate half life sulfas

Diazine

methoxazole

28

Sulfa metabolism mechanism

VIa N-4 N-acetylation

 

(in some cases N-1 glucuronidation)

29

Toxic metabolites of sulfa

Hydroxylamine and nitroso metabolites

30

First gen Quinolones have limited ___ activity

G+