Erdman - Sulfonamides Flashcards
What are the sulfonamides?
Trimethoprim-sulfamethoxazole
Sulfamethoxazole mechanism of action
Inhibits dihydropteroate synthetase by inhibiting the conversion of PABA into dihydrofolate
Trimethoprim mechanism of action
Inhibits dihydrofolate reductase by preventing reduction of dihydrofolate to tetrahydrofolate
Why is Bactrim a combo product
Each individual product is bacteriostatic but together they are bactericidal
What is the resistance mechanism to Bactrim?
Mediated by point mutations in dihydropteroate synthetase and/or altered production or sensitivity of dihydrofolate reductase
Bactrim spectrum of activity against gram-positive
Staph aureus (some MRSA, CA-MRSA) (used for unserious infections)
Bactrim spectrum of activity against gram-negative
-HENPEACKSSSS
-Stenotrophomonas maltophilia (i dont think this is on exam but idk)
-NOT pseudomonas
What is the Bactrim distribution?
-Good distribution, can get into urine and prostate
-SMX is 70% protein bound
-Does penetrate the CSF but not very well
How is Bactrim eliminated?
Both drugs in the combo are eliminated by the liver and kidney
Does Bactrim need dose adjustment in renal insufficiency?
Dose adjustment required in patients with CrCl less than 30
Bactrim clinical uses
-Acute, chronic, or recurrent infections of the urinary tract
-Acute or chronic bacterial prostatitis
-Skin infections due to CA-MRSA
-Pneumocystitis carinii/jirovecii pneumonia (DOC)
-Stenotrophomonas
Bactrim adverse effects
-Leukopenia
-Thrombocytopenia
-Hypersensitivity (rash)
-Crystalluria
-Hyperkalemia
-Increased creatinine
-Can cause kernicterus in babies when taken while pregnant or breastfeeding
Bactrim drug interactions
Can increase anticoagulation effect of warfarin
What ratio is Bactrim typically dosed?
1:5 ratio
What is double strength Bactrim?
160 TMP and 800 SMX
