Sulphonamides Flashcards
What is first chemotherapeutic agents used systemically ?
Sulphonamides
Their use declined after
Discovery of penicillins and other antibiotics and development of resistance , now use is very restricted
Chemically ?
Are derivatives of sulphanilamide ( which contains nitrogen and sulphur in its structure )
Mode of action ?
Sulphonamides are structural analogs and competitive antagonists of para- amino Benzoic acid( PABA) they prevent normal bacterial utilization of PABA for synthesis of Folic acid ,sensitive bacteria is that which can not utilize pre formed folic acid them and is not synthesized
Anti bacterial spectrum ?
-streptococcus pyogenes Haemophilus influenza Actinomyces Escheria coli Streptococcus preumonia Nocardia Chalmydia trachomatis Neisseria meniningitidis
Pharmacokinetics ?
Are rapidly absorbed ( except those acting locally on the bowel ) from GIT ,approximiately 70-100% of the dose is absorbed.major site of absorption is small intestine - bound (by varying degree to the plasma proteins ) Distributed to all body tissues.
Metabolized in liver to inactive metabolites
Excreted partly unchanged and partly as metabolites by the urinary system .
Sulphonamides which are still in use include ?
Sulphamethoxazole Sulphadiazine Sulphadoxine Sulphacetamide Sulphathiazole
Sulphamethoxazole ( Gantanol)?
Is along acting sulphanomide .administered orally for both systemic and urinary tract infections , commonly used in combination with trimethoprim ( co-trimoxazole -septrin ) to potentiale the antibacterial effect .
Dose of sulphamethoxazole?
2tablets (400 mg sulphamethazole +50 mg trimthoprim ) every 12 hours for at least five daily
Co- trimoxazole is commonly used in treatment of all systemic infections , but is specifically used for UTI and Typhoid and Toxoplasmosis
(Combined with pyrimethamine )
Sulphathiazole ?
This sulphonamide is not absorbed by GIT so its action is local ,used for local treatment of GIT infection
Sulphadiazine?
Rapidaly absorbed when given orally, partially metabolized in liver and is excreted to Bacterial Meningitis because it can cross Blood Brain Barrier BBB efficiently, usually adminstered parentrally
Dose:60 mg/k body every 4Hours.
Sulphadoxine?
Is along acting sulphonamide, used in comination with pyrimethamine ( Daraprim) (500 mg sulphadoxine +25 mg pyrimethamine - fansidar ) for treatment of malaria
Dose:- a single dose of 3 tablets
Sulphacetamide (isoptocetamide )?
A short acting sulphonamide used locally in eye infections especially chlamydia .formulated in sodium salt form ,as eye drops of 20%&30% concentration