Sulfonamides and Trimethoprim Flashcards
What were the first effective systemic chemotherapeutic agents?
Sulfonamides
What is the chemical structure of sulfonamides?
A sulfur atom attached to a benzene ring with a para amino (NH2) group
What type of bacteria are sulfonamides effective against?
Both gram-positive and gram-negative bacteria
Under what condition can sulfonamides become bactericidal?
In the absence of thymine but presence of other metabolic precursors (thymine-less cell death)
Are sulfonamides bacteriostatic or bactericidal?
Generally bacteriostatic
What drug is synergistic with sulfonamides?
Trimethoprim
Why do sulfonamides selectively target bacteria?
Because bacteria require de novo folate synthesis, while mammalian cells get folates from the diet
Sulfonamides are structural analogs of what compound?
Para-amino benzoic acid (PABA)
How do sulfonamides interfere with bacterial metabolism?
They inhibit bacterial synthesis of folic acid from PABA
How can bacteria resist sulfonamides by modifying PABA production?
By increasing synthesis of PABA (up to 70 times more in some resistant strains)
What effect do sulfonamides have on protein binding?
They can displace bilirubin from protein binding sites
What is another mechanism bacteria use to bypass sulfonamide action?
Using an alternative metabolic pathway for synthesizing essential metabolites
How can bacterial enzymes contribute to sulfonamide resistance?
Enzymes may alter to make PABA a better substrate
How else can bacteria resist sulfonamides?
By increasing their ability to destroy or inactivate the drug
How are sulfonamides absorbed and distributed in the body?
They are extensively absorbed and distributed
What body compartments do sulfonamides enter?
Central nervous system and aqueous humor
Where does metabolism of sulfonamides occur?
In the liver, specifically at the N-4 position
How are sulfonamides excreted?
By the kidneys, with high accumulation in the renal tract
What common immune-related reaction can sulfonamides cause?
Hypersensitivity reactions
How do sulfonamides behave in terms of solubility?
Each sulfonamide acts independently regarding solubility and crystallization
What urinary complication can sulfonamides cause?
Urinary tract crystallization due to the Principle of Independent Solubility
What is a common first-line use of sulfonamides?
Urinary tract infections
In which enzyme deficiency are sulfonamides potentially harmful?
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
What serious effect can sulfonamides have in newborns?
Displacement of bilirubin leading to central nervous system damage
