Folate Synthesis Inhibitors Part 3

How can sulfonamides be administered?

PO, IV, IM, IP, intrauterine, or topically depending on the preparation.

How are most sulfonamides absorbed in monogastric animals?

Rapidly and almost completely from the gastrointestinal tract.

How is sulfonamide absorption affected in ruminants?

Absorption is delayed because the drug is retained in the ruminoreticulum.

What condition further delays sulfonamide absorption in ruminants?

Ruminal stasis.

Which sulfonamide has decreased bioavailability when administered with feed?

Sulfachlorpyridazine.

How are sulfonamides absorbed after parenteral administration?

Rapidly.

Why are some sulfonamides formulated as sodium salts for injection?

To increase water solubility and allow parenteral administration.

Where are sulfonamides distributed after absorption?

Most body fluids.

Which drug has greater tissue distribution: sulfonamides or trimethoprim?

Trimethoprim.

How does protein binding affect sulfonamides?

It reduces distribution and prolongs the drug's half-life.

Which tissue receives the lowest concentration of sulfonamides?

The central nervous system (CNS).

Can sulfonamides enter milk?

Yes, but concentrations are usually too low to effectively treat infections.

Why are sulfonamide residues in milk important?

They may remain as drug residues even when concentrations are not therapeutic.

Where are sulfonamides primarily metabolized?

In the liver.

What are the major metabolic pathways of sulfonamides?

Oxidation, acetylation, and conjugation with sulfate or glucuronic acid.

Which species does NOT acetylate sulfonamides?

Dogs.

How does acetylation affect sulfonamides?

It decreases water solubility and increases the risk of crystalluria.

Do acetylated sulfonamide metabolites have significant antibacterial activity?

No, they have little to no antibacterial activity.

What is the primary route of sulfonamide excretion?

Urine.

What renal processes eliminate sulfonamides?

Glomerular filtration, active tubular secretion, and tubular reabsorption.

What are the minor routes of sulfonamide excretion?

Bile, feces, milk, tears, and sweat.

How is trimethoprim absorbed after oral administration?

Rapidly, except in ruminants.

Why is trimethoprim poorly absorbed in ruminants?

It becomes trapped in the ruminoreticulum and may undergo microbial degradation.

Which tissues achieve high concentrations of trimethoprim?

Lungs, kidneys, CSF, joint fluid, bone, prostate, and eyes.

How does the volume of distribution of trimethoprim compare with sulfonamides?

Trimethoprim has a larger volume of distribution.

Why does trimethoprim accumulate in acidic environments?

It is an organic base that undergoes ion trapping.

Name acidic body fluids where trimethoprim accumulates.

Urine, milk, and ruminal fluid.

What is the primary route of trimethoprim excretion?

Urine via glomerular filtration and tubular secretion.

What is another route of trimethoprim elimination?

Feces.