Exam 2: Sulfonamides Flashcards
What are the 3 kinds of sulfonamides and how are they administered?
1) sulfamethoxazole: Oral, slow excretion, high urine concentration
2) Sulfasalazine: Oral, used for UC
3) Silver Sulfadiazine- topical, used for burns
What is the DOC for UTIs?
Co-trimoxazole
What is the MOA of sulfonamides?
Antimetabolites that compete with para-aminobenzoic acid for incorporation into folic acid.
-Bacteriostatic
What is the MOA of trimethoprim?
Prevents the reduction of dihydrofolate to tetrahydrofolate which is essential for one carbon transfer
Why are sulfamethoxazole and trimethoprim taken together?
They each target different steps and have a synergistic relationship together
What are the routes of resistance for sulfamethoxazole and trimethoprim?
- Increased production of an essential metabolite or drug antagonist
- Active Efflux or decreased permeability
- Alternative metabolic pathway for synthesis of essential metabolite
Is TMO-SMZ bacteriostatic or cidal?
Cidal in the urine, static everywhere else
What is the spectrum of sulfa drugs?
Both G+ and G- organisms (some aerobes and anaerobes)
What are the therapeutic uses of sulfasalazine?
A prodrug used in the treatment of mild to moderate UC, Crohns, and RA.
When taking Suflamethoxazole trimethoprim, how much higher will the urine concentration be when compared to the plasma concentration?
10-20 times higher
What are the toxicities associated with Sulfa drugs?
Blood dyscrasia (asplastic anemia, G6PD deficiency), photosensitivity, hypersensitivity, SJS, kidney/liver damage, and peripheral nerve damage
Why shouldn’t sulfas be given to infants?
It can cause Kernicterus because the sulfas compete with the binding of bilirubin to the plasma proteins
What drugs so sulfas have cross reactivity with?
Diuretics, celecoxib, and some oral anti diabetic agents
What is the MOA of daptomycin?
Binds to Bacterial membranes and causes a rapid depolarization of membrane potential, which leads to inhibition of protein, DNA, and RNA synthesis.
How does daptomycin cause membrane depolarization?
It forms transmembrane channels, which allows leakage of intracellular ions and depolarization
What the spectrum of Daptomycin?
bactericidal against G+ bacteria (MRSA and MSSA)
- Aerobic or anaerobic
- Concentrastion dependent
How does Daptomycin resistance develop?
Resistance is very rare, but does exist. Mechanism for this resistance has not been identified.
How is Daptomycin administered?
IV, once daily.
What kind of patients is Daptomycin suitable for?
Empiric therapy in patients with serious G+ infections as an alternate to Vancomycin
What is the MOA of Mupirocin?
Bacterial protein and RNA synthesis inhibited when mupirocin reversibly binds to bacterial isoleucyl-tRNA synthetase
What is the spectrum of Mupirocin?
Good against G+ and G-. Bacteriostatic at low concentrations and cidal at high concentrations.
-Administered topically
What is Mupirocin used to treat?
Impetigo caused by S. Aureus.
Intranasal application for pts who carry MRSA
What are the two polypeptide antibiotics?
Polymyxin B and Colistin
What is the spectrum for polypeptide antibiotics?
G- infections
