Antibacterial Agents Flashcards
Drugs that inhibit cell metabolism (1 example)
Sulfonamides (antimetabolites)
Drugs that inhibit cell wall synthesis (3)
Penicillin Cephalosporins Vancomycin
Drugs that affect the plasma membrane (2)
Polymyxins Tryothricin
Drugs that disrupt protein synthesis (4)
Chloramphenicol Aminoglycosides Rifamycins Tetracyclins
Drugs that inhibit NA transcription and replication (2)
Nalidixic acid Proflavine
Sulfonamides were discovered from this compound
Prontosil (a prodrug converted to sulfanilamide)
Sulfonamide SARS
- All groups are essential for activity
- Should be para-substituted only
- Nitrogen must only be primary or secondary
- R1 must be unsubstituted unless it’s an amide (which can be metabolized)
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Long lasting sulfonamide
Sulfadoxine
(taken only once a week)
Sulfonamide combination for malaria
Sulfadoxine + Pyrimethamine
(Fansidar)
Sulfonamides MOA
- Mimic p-aminobenzoic acid (PABA) to inhibit dihydropteroate synthetase
- Block tetrahydrofolate synthesis, a cofactor for pyrimidine synthesis (for DNA)
Trimethoprim (antimetabolite) MOA
Sulfone (antimetabolite) indication
Leprosy
Baterial cell wall sugars (2)
- N-Acetylmuramic acid (NAM)
- N-Acetylglucosamine (NAG)
Succesfully isolated penicillin using processes such as freeze-drying and chromatography
Florey and Chain
Enzyme inhibited by penicillin
Transpeptidase
Penicillin action (G+ or G-)
- G+ since although they have a thicker cell wall, G- have a lipopolysaccharide barrier impervious to water and polar molecules
- Futhermore, most G- have b-lactamases
- G- activity if there are porins (allow hydrophilic, zwitterions to cross)
- A G+ bacteria may be immune if it has b-lactamases
Penicillin SARS
- Bicyclic system: the greater the strain the greater the activity
- All are essential EXCEPT sulfur
Adding an electron withdrawing group to the acyl side chain of the penicillin structure will render the drug:
Resistant to acid hydrolysis