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Sulfa drugs -Mechanism of action
sulfa substitutes for PABA which bacteria use to make folic acid sulfa drugs are analogs of PABA sulfa inhibits dihydropteroate synthase in bacteria TERM 2
Sulfa drugs -Activity
DEFINITION 2 poor against anarobes good for a wide range of organisms gram neg and pos norcardia Chlamydia some enteric (E. coli and klebsiella, salmonella, shigella,enterobacter) TERM 3
Sulfa drugs - Resistance
DEFINITION 3 mutations in the bacteria that cause (a) increased synthesis of PABA (b) produce the synthesizing enzyme for folic acid that has reduced affinity for sulfa drugs (c) reduced permeability in cell wall to sulfa drugs TERM 4
Sulfa Drugs - Pharmacokinetics
DEFINITION 4 (a) oral absorbable (b) oral nonabsorable (c) topical TERM 5
Sulfa Drugs - ADRs
DEFINITION 5 (a) allergy (b) Stevens Johnson syndrome (rare, < 1%)
Sulfa Drugs - Combination to prevent
resistance
(a) trimethoprim inhibit bacterial dihydrofolic acid reductase TERM 7
Sulfa Drugs - Drug Actions
DEFINITION 7 (a) bacteriostatic all sulfa drugs except combination (b) bactericidal combination with trimethoprim TERM 8
Sulfonamide -Structure / Source
DEFINITION 8 Prontosil biotransformed in the liver to sulfonamide Prontosil is a prodrug converted in vivo to sulfonamide The para-NH2 is essential for antibiotic activity. Most sulfa drugs made from substitutions in the sulfur portion of the molecule. TERM 9
Sulfonamide - Mechanism of Action
DEFINITION 9 Bacteria have unique synthetic pathway used to produce folic required for DNA synthesis. Synthesis starts with p-amino benzoic acid (PABA). In bacteria (not mammals) folic acid is synthesized from PABA Sulfa substitutes for PABA and blocks folic acid synthesis. Folic acid loss results in impaired DNA synthesis. Bacteriostatic. TERM 10
Sulfonamide - Pharmacokinetics
DEFINITION 10 F = 70 -100 % following po dose Peak Cp levels in 2 - 6 h post po dose Drug distributes into most tissues including brain and CSF. Major biotransformation is through acetylation. Most metabolites are inactive
Trimethoprim/Sulfamethoxazole
Also called cotrimoxazole. Mostly used for urinary tract infections but high distribution into tissues after po dosing makes it useful for lower extremity infections. Bacteriostatic against all organisms tested. Good for staph and MRSA Used to treat Pneumocystis pneumonia in AIDS patients. Allergic reactions possible from mild rash to Stevens-Johnson Syndrome (systemic skin disease)Hemolytic anemia in patients with G6PD deficiency TERM 17
Sulfisoxazole
DEFINITION 17 oral used only for lower UTI infections TERM 18
Sulfadiazine
DEFINITION 18 oral first line of therapy for toxoplasmosis when combined with pyrimethamine TERM 19
Trimethoprim
DEFINITION 19 oral used only for lower UTI infections may be safely prescribed to patients with sulfonamide allergy TERM 20
Pyrimethamine
DEFINITION 20 oral first line therapy for toxoplasmosis when combined with sulfadiazine coadminister with leucovorin to limit bone marrow toxicity
Pyrimethamine-sulfadoxine
oral second line malaria treatment
