L27: Sulfa

Question 1

Sulfa are competitive inhibitors of _____

Answer 1

dihydropteroate synthase

Question 2

How do Sulfa drug inhibit folate synthesis?

Answer 2

mimick PABA (end result: no DNA synthesis)

Question 3

Sulf drugs have more bacteriostatic effect, but the exception is ____

Answer 3

TMP-SMX

Question 4

Which organisms are sensitive to sulfa drugs?

Answer 4

Those that make their own folic acid

• Those that obtain pre-formed folate are resistance (human cells)

Question 5

Trimethoprim and Pyrimethamine inhibit conversion of DHF acid to ____. They inhibit the enzyme ___

Answer 5

THF acid; DHFR

Question 6

Mutated ____ lowers drug affinity in sulfa drugs

Answer 6

dihydropteroate synthase

Question 7

Most sulfa drugs have good oral availability, except ___

Answer 7

sulfasalazine

Question 8

Which sulfa is poorly absorbed, but active in bowel lumen?
A. sulfasalazine
B. sulfadiazine
C. sulfamethoxazole

Answer 8

A. sulfasalazine

Question 9

Which two sulf are topical agents?
A. sulfasalazine
B. sulfadiazine
C. sulfamethoxazole
D. silver sulfadiazine
E. sulfacetamide mafenide

Answer 9

D. silver sulfadiazine
E. sulfacetamide mafenide

Question 10

which two sulf drugs are absorbed/excrete rapidly?

Answer 10

Sulfamethoxazole/sulfadiazine

Question 11

_____ has topical anti-inflammatory effects for UC and in RA

Answer 11

Sulfasalazine

Question 12

____ mainstay for 2nd and 3rd degree burn therapy, which is effective against bacteria and fungi

Answer 12

Silver Sulfadiazine

Question 13

Sulfacetamide is available as topical (Klaron) or opthalamic (Bleph). What are the uses for topical? opthalamic?

Answer 13

topical
- acne
- bacterial infections

opthalamic
- pink eye
- trachoma

Question 14

_____ is also used in burn therapy. but, since its metabolite inhibits CA, it may lead to met acidosis.

Answer 14

Mafenide

Question 15

Sulfamethoxazole must be given with ___ while sulfadizine must be given with ____

Answer 15

Sulfamethoxazole + TMP

Sulfadiazine + Pyrimethamine

Question 16

TMP-SMX is preg cat __ while sulfadiazine is used to prevent ___ transmission

Answer 16

D; T. gondii

Question 17

True or False: Trimethoprim+Sulfamethoxazole (TMP-SMX) are bactericidal and give dual inhibition

Answer 17

True

Question 18

Use of TMP-SMX?

Answer 18

1. Community acquired MRSA/ORSA

Question 19

True or False: Rickettsiae is stimulated by TMP-SMX

Answer 19

True

Question 20

True or False: Oral sulfonamides/trimethoprim can be used to treat UTI’s and prostatitis

Answer 20

True

Question 21

True or False: Trimethoprim + Sulfmethoxazole can treat complicated and uncomplicated UTI’s

Answer 21

True

Question 22

True or False: Oral sulfonamides and TMP can be used for respiratory infections, but not usually for pneumonia

Answer 22

True

Question 23

TMP-SMX can treat PCP (pneumocystitis pneumonia) caused by _____

Answer 23

pneumocystis jirovecii

Question 24

AE with sulfa drugs?

Answer 24

1. hypersensitivity
2. skin rash
3. photsensitivity
4. crystalluria
5. SJS
6. kernicterus
   - bilirubin can cross BBB

Question 25

Sulfoamides inhibit ___ while trimethoprim and pyrimethamine inhibit ____

Answer 25

dihydropteroate synthase; dihydrofolate reductase

Question 26

True or False: TMP-SMX combo is commonly used for UTI’s, respiratory infections, and some GI

Answer 26

True

Question 27

True or False: Bactrim (TMP-SMX) is pregnancy cat D, should be avoided when possible

Answer 27

True