Sulfas

Question 1

What are the intermediate acting sulfas?

Answer 1

Sulfaimethoxine, Sulfamethoxazole, Sulfamethazine, Sulfadiazine

Question 2

Why is sulfa (Albon) a common residue even after a withdrawal period?

Answer 2

Variation in elimination between ill and healthy animals

Question 3

What are the long acting sulfas?

Answer 3

Sulfadimethoxine, sulfamethazine

Question 4

What is the enteric sulfa? Which species should you use caution in? Why?

Answer 4

Sulfasalazine

Be careful in cats (especially with IBS/leaky gut) because of salicylic acid

Question 5

What are the diaminopyrimidines?

Answer 5

Trimethoprim, Ormethoprim

Question 6

What are come common combinations?

Answer 6

Trimethoprim/sulfa, ormethoprim/sulfa, trimethoprim/sulfamethoxazole

Question 7

Can you use sulfas in lactating dairy cattle?

Answer 7

Only approved use of sulfadimethoxine (most important), sulfabromomethazine, sulfaethoxypyridazine

Question 8

Are sulfas soluble in solution?

Answer 8

Each sulfa has independent solubility in solution

Question 9

Are sulfas acids or bases?

Answer 9

Weak acids

Question 10

Are sulfas water soluble in acid form?

Answer 10

No

Question 11

If you treat a sulfa with a strong base, what will it form?

Answer 11

Soluble, sodium salt

Question 12

Are sulfa sodium salts acidic or basic? What is the pH? What’s the exception?

Answer 12

Basic 9 - 11

Sulfacetamide is neutral

Question 13

Which sulfa is used an opthalmic solution? Why?

Answer 13

Sulfacetamide because it’s neutral

Question 14

Is trimethoprim an acid or base?

Answer 14

Weak base (pKA 7.6)

Question 15

Is trimethoprim water or lipid soluble?

Answer 15

Lipid

Question 16

Why are sodium salts delivered IV only and never IM?

Answer 16

Very caustic due to alkalinity

Question 17

What is the MOA of sulfas?

Answer 17

Sulfas compete with PABA for incorporation in to folic acid synthesis. Folic acid is necessary for purine synthesis. Decreases RNA and inhibits protein synthesis

Question 18

What can cause sulfas decreased activity? Why?

Answer 18

cellular debris from folic acid is readily available from the environment

Question 19

Why is it difficult to extrapolate lab susceptbility to clinical efficacy?

Answer 19

Cellular debris effect & bacterial-inoculum effect

Question 20

Are Sulfas bacteristatic or bactericidal?

Answer 20

Static but can be -cidal when combined with trimethoprim

Question 21

What happens when you combine a sulfa with a diaminopyrimidine?

Answer 21

Synergistic combo acting in bactericidal manner against susceptible microbes

Question 22

What is the spectrum of sulfas (non- potentiated)?

Answer 22

++ in all quadrants & coccidia

Question 23

What is the spectrum for potentiated sulfas?

Answer 23

+++++

Question 24

Which organisms are resistant to generalized sulfas?

Answer 24

Mycobacterium, mycoplasma, Rickettsia, pseudomonas, spirochetes

Question 25

Which 2 organisms do potentiated sulfas gain efficacy against?

Answer 25

Mycobacterium, Norcardia

Question 26

Is resistance to sulfas common or uncommon?

Answer 26

Very common

Question 27

What route should sulfadimethoxine (Albon) be administered?

Answer 27

IV | Oral

Question 28

How is sulfadimethoxine given orally to food animals? Small animals?

Answer 28

Oral bolus or soluble powder for food animals Tablets or oral suspension for small animals

Question 29

What is the name of the sulfa tablets given to dogs?

Answer 29

Primor

Question 30

How is Trimethoprim/Sulfadiazine administered?

Answer 30

IV | Oral paste/tablets

Question 31

Can you use TMP/Sulfadiazine in horses? Cattle?

Answer 31

Yes | NO

Question 32

What are the routes of administration for Sulfamethazine in food animals?

Answer 32

``` Oral bolus for cattle Top dress (granules or powder) for swine, cattle ```

Question 33

How is sulfachlorpyridazine administered?

Answer 33

IV in calves | Soluble powder in pigs/calves

Question 34

What is sulfasalazine? Can it be used in food animal?

Answer 34

Oral, enteric-coated tablets labeled for human use. | NO USE IN FOOD ANIMAL

Question 35

Are sulfas highly bioavailable?

Answer 35

Mostly

Question 36

Are sulfas variably in their bioavailability ot uniform? What may be some variables?

Answer 36

Variable across species, between sulfas in degree of protein binding & Vd and half-life

Question 37

What is the half-life in cattle for Sulfamethazine? Is it legal for use in cattle? Sulfamethoxazole?

Answer 37

680 minutes, yes? | 140 minutes, no?

Question 38

What is a drawback to sulfamethoxazole in regards to its half-life?

Answer 38

Doesn't stay above MIC long enough

Question 39

Why is it common to give a loading dose of sulfa?

Answer 39

To maintain above MIC for continued therapy

Question 40

What is the elimination method for sulfas?

Answer 40

Primarily hepatic via acetylation | Also renal excretion

Question 41

Are sulfas bacteristatic or cidal?

Answer 41

Static

Question 42

What is the efficacy of sulfas closely linked to?

Answer 42

Time above MIC

Question 43

What is a major change in efficacy when sulfas are combined with diaminopyridimine?

Answer 43

Become bactericidal

Question 44

Are there any sulfas that have veterinary derived breakpoints?

Answer 44

No, all human

Question 45

What is the most important adverse effect of sulfas in dogs?

Answer 45

Keratoconjunctivitis sicca after long-term therapy of sulfadiazine

Question 46

Other than KCS, what are some adverse effects on sulfas in dogs?

Answer 46

NEUTROPENIA, bone marrow depression, hypersensitivity, nonseptic polyarthritis, hepatic necrosis, thrombocytopenia

Question 47

What is a possible urinalysis finding of a dog on sulfas?

Answer 47

Crystalluria

Question 48

What is a GI problem with long term sulfas?

Answer 48

Enteric flora alteration

Question 49

Should any sulfas be given other than IV/oral in food animals? Why?

Answer 49

IM injection can cause extensive carcass blemish

Question 50

What is the association between sulfaquinoxaline and vitamin K? What is the issue?

Answer 50

Sulfaquinoxaline antagonizes vitamin K and can lead to hemorrhage in patients with bleeding disorders

Question 51

What is the association between thyroid hormone and sulfas?

Answer 51

Long term sulfa use may induce mild thyroid dysfunction

Question 52

Sulfas may be used in dogs once certain cases are ruled out, what are these cases?

Answer 52

History of KCS, liver disease, thyroid therapy, Dobermans (von Willebrand's)

Question 53

Pyrimethamine is used in mares being treated for EPM. What are some issues associated with pyrimethamine?

Answer 53

Tetatogenic