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sulfonamides.ppt

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Sulfonamides are a class of antimicrobial drugs that work by inhibiting the enzyme dihydrofolate reductase. They can be classified as orally absorbable or non-absorbable, and also include topical formulations. Sulfonamides have a broad antimicrobial spectrum and are commonly used in combination with other drugs like trimethoprim in cotrimoxazole to treat various infections. However, they can cause adverse effects like crystalluria, hypersensitivity reactions, and kernicterus in neonates due to drug interactions and toxicity in high doses.

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Sulfonamides Sulfa drugs
Contents ? History ? Mechanism of action ? Classification of Sulfonamides ? Orally absorbable sulfonamides ? Orally non absorbable sulfonamides ? Topical sulfonamides ? Adverse effect ? Drug interactions
sulfonamides.ppt
Mechanism of Action
? inhibit enzyme dihydrofolate reductase Trimethoprim ? Analogue of trimethoprim Iclaprim ? inhibit dihudrofolate reductase ( affinity for protozoa) Pyremethamine
Antibacteria effect overcome (Resistance) Excess formation of PABA Presence of pus
Orally Non absorbable agents Orally absorabable agents
Synergistic combination with sulfonamides sulfamethaxazole Trimethoprim Cotrimoxazole
Sulfadoxine Pyrimethamine Block protozoal folic acid synthesis
Antimicrobial Spectrum Active ? Gram negative bacilli ? E.coli, shigella, salmonella Moderately active ? Actinomycetes ? Rickettsiea
Resistance Mutation Overproduction of PABA Alteration in dihydropteroic acid syntetase Loss of permeability of sulfonamide Alternative pathway for PABA synthesis
Pharmacokinetics ? orally ? X IM/SC ? Topical ? IV Absorption ? Crosses BBB ? Accumulate in prostatic fluid ? Protein binding 85-93 % Distribution ? Acetylation in liver Metabolism
Clinical Uses ? Rarely used as single agent ? Topical sulfonamides- ulcerative colitis sulfamethaxazole Trimethoprim Cotrimoxazole
Indications of cotrimoxazole ? UTI¡¯s ? Prostatitis ? Respiratory tract infection ? Typhoid ? Bacterial diarrheas and dysentery ? Nocardiosis ? Sexually Transmitted disease ? Pneumonia ? Melioidosis
?Toxoplasmosis Sulfadiazene + Pyrimethamine ?Malaria Sulfadoxine + Pyrimethamine
Oral non absorbable sulfonamide ? Drug of choice- Ulcerative Colitis ? Absorb through GIT ? Degaded by Bacterial flora of colon 5-Amino Salicylic acid Sulfapyridine
Topical agents ? Trachoma(chlamydia) ? Bacterial conjunctivitis Sodium sulfacetamide ? Prevention of infection in burn cases ? Antimicrobial (Ag+) Silver Sulfadiazene ? Burn cases ? Active even in presence of pus Mafenide
Adverse effect Crystalluria and renal toxicity ?Less soluble in acidic urine ?Use of 3 sulfa drugs Hypersensitivity reaction ?Stevens Johnson syndrome ?Eosinophllia Kernictus in neonates ?Cross BBB Haemolytic anaemia ?Deficiency of glucose-6- phosphate dehydrogenase Cotrimoxazole fever Hypersensitivity Agranulocytosis
Drug Interactions Sulfonamides Oral anticoagulants, sulfonyl ureas, Methotrexate

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sulfonamides.ppt