L 6 Sulfonamides

Question 1

What is the MOA for Sulfonamides?

Answer 1

Inhibition of DNA synthesis by competing for the enzyme needed for folic acid synthesis
Bacteriostatic–requires functioning immune system

Question 2

How are Sulfonamides eliminated?

Answer 2

They are metabolized in the liver by acetylation and then excreted in the kidney

Question 3

Difference between Trimethoprim and Methotraxate in function

Answer 3

Both inhibit Dihydrofolate Reductase, an enzyme needed for the production of folic acid and DNA
Trimethoprim is more specific to lower organisms whereas Methotrexate is more human specific and therefore has an effect on rapidly reproducing cells like bone, hair, GI

Question 4

Coverage and use of Sulfonamides

Answer 4

g(+) and g(-) coverage
Used for UTI’s, Nocardiosis, Toxoplasmosis, Trachoma
TMP-SMX: Moraxella and UTI
Otitis media occasionally and Listeria

Question 5

Mode of admin for Sulfonamides

Answer 5

Oral

Question 6

Tissue distribution of Sulfonamides

Answer 6

Crosses the placenta and enters the CNS

Urine concentration 10-20x plasma makes it DOC for UTI’s

Question 7

What is a downside to the high concentration of Sulfonamides in the urine?

Answer 7

Sulfonamides are acetylated by the liver and are then poorly soluble in water and form crystals in acidic urine causing nephrotoxicity and renal failure

Question 8

What is a significant drug interaction of Sulfonamides?

Answer 8

They can have high plasma protein binding and cause adverse reactions with Warfarin

Question 9

Sulfonamides and pregnancy

Answer 9

Caution should be taken because Sulfonamides cross the placenta and displace bilirubin leading to potential kernicterus in the fetus
Also excreted in milk and can get to the baby that way

Question 10

Toxicity with Sulfonamides

Answer 10

Kernicterus in children
Blood dyscrasia
Hemolytic anemia
Microscopic hematuria
Stevens-Johnson
Photosensitivity
Peripheral nerve damage
Contact dermatitis

Question 11

Sulfadiazine

Answer 11

Oral
Combo with Pyrimethamine for Toxoplasmosis
Not used

Question 12

Trimethoprim

Answer 12

Sulfonamide
Used for UTI’s, Traveler’s diarrhea
Not used

Question 13

Silver sulfadiazine (silvadene)

Answer 13

Topical anti-infective for severe burns

Good for bac and yeast

Question 14

Pyrethamine + Sulfadoxine (Fansidar)

Answer 14

Used for presumptive malaria and not for prophylaxis

Can cause Toxic Epidermal Necrolysis (Stevens-Johnson)