Sulphonamides ,Short Introduction about the sulpha Drugs.

Short Introduction about the sulpha Drugs.

1. Sulpha drugs BY MOHD JUNAID KHAN

2. OUTLINES INTRODUCTION MECHANISM OF ACTION ANTIBACTERIAL OF ACTION PHARMACOKINETICS INDICATION ADR PREGNANCY/LACTATION ADMINISTRATION& DOSAGE PATIENT REFERENCE

3. INTRODUCTION The Sulphoamides are synthetic bacteriostatic antibiotics with a wide Spectrum against most gram positive and many gram negative oraganism However, many strains of an individual species may be resistant

4. Structure of sulphonamides

5. MECHANISM OF ACTION Many bacteria must rely to their ability to synthesize folate from PABA . In contrast, human beings cannot synthesize folic acid and must obtain performed folate as vitamin in their diet. Because of their structural similarity to PABA ,the sulphonamides compete with this substrate for the enzyme dihydropteroate synthetase, thus preventing the synthesis of bacterial folic acid (coenzymes are required for synthesis of purines and pyrimidines ). Resulting in inhibition of RNA & DNA synthesis .In absence of folic acid cells cannot grow or divide.

6. ANTIBACTERIAL OF ACTION Sulphoamides are active against gram + ve cooci (staph.& strepto .) & bacilli (clostridium tetani). Also, sulfas active against gram - ve cocci (Neisseria gonorrhoeae) & Bacilli (E.coli).

7. PHARMACOKINETICS Absorption:-most Sulphonamides Are Readily Absorbed Orally. However Parenteral Administration Is Difficult. Since The Soluble Sulphonamides Salts Are Highly Alkaline And Irritating To The Tissues. Distribution The Sulphonamides Are Widely Distributed Throughout All Tissues High Levels Are Achieved In Pleural Peritoneal ,Synovial And Ocular Fluids .Although These Drugs Are No Longer Used To Treat Meningeal Infections Their Antibacterial Action Inhibited By Pus

8. Dihydropteroate Synthase Dihydrofolate Reductase Sulphonamides (Compete With PABA) Trimethoprim Action Of Sulphonamides And Trimethoprim Tetrahydofolic Acid Dihydrofolic Acid Purines DNA

9. Metabolism : Primarily in liver.The product is Devoid of Antimicrobial activity,but it retains the toxic potential to precipitate at neutral or acidic PH,causing crystalluria (stone formation ),leading to kidney damage. Excretion : Excretion is primarily renal by glomerular filtration with minimal tubular Secretion or reabsorption.

10. D-INDICATIONS: Oral Absorable ( eg.Sulfamethoxazole ) .Urinary tract infections (infrequently used alone) Oral Nonabsorable ( eg.Sulfasalazine ) .Ulcerative colitis,inflammatory bowel disease .Metabolized by gut-microflora .Metabolized are anti -inflammatory Topical ( eg.Sulfacetamide ) Bacterial Conjunctivitis (Pink –Eye) Infections Resulting From Burns or Wounds In Combination with Pyrimethamine in the treatment of toxoplasmosis, As a substitute for Penicillin in pyrophylaxis of rheumatic fever

11. E-Adverse Effect 1-Crysalluria 2-Hypersensitivity 3-Hemolytic anaemia: with G6PD deficiency . 4-Kernicterus : occur in new Born because sulfas displace bilirubin from binding site on serum albumin 5-Drug Potentiation : with Tolbutamide or warfarin . 6-stevens-Johnson syndrome: Occurs in<1% of treatment courses Skin and Mucous Membrane eruption.

12. F- sulfonamide Resistance 1 Decreased Permeability to Sulphonamide 2 lack dihydropteroate synthase 3 Mutation Resulting in PABA synthesis 4 Mutation in dihydropteroate synthase so sulphonamide can not bind

13. G-PREGNANCY\LACTATION Avoided in Newborn & pregnant women . When these drugs are given in Pregnancy ,high levels are achieved in The fetus ---------  Kernicterus

14. H-ADMINISTRATION& DOSAGE Systemic sulfonamides :An initial loading dose is commonly recommended but is unnecessary and should not be used in treating UTI (the major use for sulphonamides).It is rarely needed for most other indications. Sulfisoxazole :is used in a dosage of 1g q 4 to 6 h po in adults (if a loading dose is used ,it is 2 to 4g.) In children ,150 mg/kg/day is given orally in 6 divided doses;the loading dose if used is 75 mg/kg. Sulfamethoxazle is used orally in dosage of 1g bid to tid in adult and 25 to 30 mg/kg bid in children .(loading doses are 2 g in adults and 50 to 60 mg/kg in children) Sulfadiazine is used in the same doses are sulfisoxazole . Sulfamethizole is used in a dosage of 500 to 1000 mg tid to qid in adults and 30 to 45 mg/kg/day in 4 divided doses in children . Topical sulfonamides : Silver sulfadiazine and mafenide are used topically to prevent infection in burns. Sulfacetamides is useful in treating ocular infections.

15. I-PATIENT To avoid crystalluria and renal damage ,fluid intake should be sufficient to produce a urinary output of 1200 to 1500 mL/day Sulphonamides should not be used in renal insufficiency.

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