Sulfonamides oral anti coagulants sulfonyl ureas

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Unformatted text preview: ntimicrobial agents.” What is antibiotic spectrum? • • Most G+ and G− But, spread of resistance • Mammalian cells use preformed folate from diet • • TMP - highly selective inhibitor of DHFR of They do not synthesize it Bacteria doenst have mechanism to import folic acid from extracullalar space into intracellualr space bacteria • Human DHFR requires 60 - 100,000 times more drug than bacterial DHFR • Why is such selectivity important in this case? Sunday, March 31, 2013 • Because …….. ? 24 SMX/TMP = 20/1 • Resistance? • • • Acquisition of a plasmid that encodes altered DHFR • Inhibitory on 2 sequential steps in biosynthesis of THF Emergent • • • Regional Staphylococcus aureus Enterobacteriaceae } Problem in AIDS patients Why is resistance a particular problem in AIDS patients? • SMX/TMP is used for prophylaxis of Pneumocystis jiroveci pneumonia -form of ammonia in AIDS patients Sunday, March 31, 2013 25 SMX/TMP = 20/1 • • Therapeutic uses • • • • • UTI Bacterial respiratory tract infection GI infection Infection by Pneumocystic jiroveci Prophylaxis of neutropenic patients Adverse effects? • • • Sunday, March 31, 2013 Selective toxicity,Yes! But • What happens in the patient who is folate deficient? • TI is narrowed = toxic rxn due to reduction in RNA/DNA/Protein synthesis SMX/TMP → megablastocis, leukopenia, thrombocytopenia 26 • The combination of trimethoprim and sulfamethoxazole inhibits the synthesis of __________ • Folic acid • Dihydropteroic acid • Dihydrofolate • Tetrahydrofolate Sunday, March 31, 2013 27 • This combination of antibiotics, TMP-SMX, has activity against some aerobic ______ • Gram + organisms • Gram − organisms • Gram + and Gram − organisms Sunday, March 31, 2013 28 • Which of the following statements about sulfonamides are false or true? • • Sulfonamides are structural analogs of PABA T • Sulfonamide crystalluria is most likely to occur at low urinary pH T • Resistant bacterial strains may have decreased intracellular accumulation of sulfonamides T • Some bacterial stains become resistant because of increased production of PABA T F Sunday, March 31, 2013 Sulfonamides inhibit bacterial dihydrofolate reductase (trimethoprine is what inhibits DFR) 29...
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This note was uploaded on 09/27/2013 for the course PMY 406 taught by Professor Berman during the Spring '11 term at SUNY Buffalo.

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