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SULFONAMIDES

SULFONAMIDES. Now largely superceded by antibiotics and trimethoprim-sulfamethoxazole. They continue to occupy a small place in therapy. Wheel of Bugs. Gram-negative. H. influenzae. Neissseria spp. E. Coli (coliforms). Bacteroides spp. P. aeruginosa. Anaerobic. Clostridium spp.

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SULFONAMIDES

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  1. SULFONAMIDES • Now largely superceded by antibiotics and trimethoprim-sulfamethoxazole. • They continue to occupy a small place in therapy.

  2. Wheel of Bugs Gram-negative H. influenzae Neissseria spp E. Coli (coliforms) Bacteroides spp P. aeruginosa Anaerobic Clostridium spp S. aureus Streptococcus spp Enterococcus spp Gram-positive

  3. 2HN SO2NH2 FOLIC ACID BIOSYNTHESIS DIHYDROPTERIDINE 2 ATP PYROPHOSPHATE DERIVATIVE Dihydropteroate Synthetase 2HN COOH DIHYDROPTEROIC ACID Glutamic Acid DIHYDROFOLIC ACID

  4. BLOOD Protein Bound Kidney Metabolites Oral X Topical Parenteral Other-Sweat, Free Saliva, Prostatic fluid, Stool Body Fluids & Tissues CSF

  5. KERNICTERUS IN THE NEWBORN • Displacement of bilirubin from plasma protein binding sites.

  6. O 3HC C N METABOLISM H SO2N R Acetylated sulfonamides-inactive, toxic, and less soluble

  7. EXCRETION • They are excreted in the urine partly as the parent and partly as the metabolite. • Some sulfonamides are very insoluble in the acid urine.

  8. EXCRETION • Half life of the sulfonamides depends on renal function. • Dosage should be modified or the sulfonamides should not be used in renal failure.

  9. SULFONAMIDE PREPARATIONS • Rapidly absorbed and rapidly eliminated (prototype- sulfisoxazole). • Poorly absorbed sulfonamides (sulfasalazine). • Topical sulfonamides (sulfacetamide, silver sulfadiazine). • Long-acting sulfonamides (sulfadoxine)

  10. CONTRAINDICATIONS

  11. DRUG-DRUG INTERACTIONS • Inhibit metabolism of some drugs. • Displace certain drugs from plasma albumin.

  12. TRIMETHOPRIM-SULFAMETHOXAZOLE OCH3 2HN CH OCH3 2 OCH3 80 mg TRIMETHOPRIM 2HN SO2NH N CH3 O 400 mg SULFAMETHOXAZOLE

  13. COTRIMOXAZOLE • Optimal ratio of the two drugs is 5:1 sulfa :trimethoprim.

  14. Synergism

  15. ADVANTAGES • Expanded number of organisms inhibited. • Bactericidal . • Decreased resistance. • Decreased toxicity.

  16. THERAPEUTIC USES

  17. hcd2.bupa.co.uk/.../ html

  18. PNEUMOCYSTIS PNEUMONIA (PCP)

  19. PNEUMOCYSTIS PNEUMONIA (PCP) www.learningradiology.com/

  20. PNEUMOCYSTIS PNEUMONIA (PCP) • The most common opportunistic infection in advanced AIDS (80% of AIDS patients have at least one episode). • Now considered a fungus (P.jurovecii). • Multiple infections are often present simultaneously with the PCP.

  21. PROPHYLAXIS • Routine prophylaxis has been successful in improving survival. • PCP prophylaxis is indicated if the patient has a CD4 T lymphocyte count lower than 200 cells/mm3, or has oral candidiasis regardless of the CD4 count.

  22. TREATMENT OF PCP • Early therapy is essential as success of therapy is related to severity of the disease at the time of initiation of therapy.

  23. TMP-SMX • Treatment of choice. • Oral form used for mild-moderate cases or after initial response to IV therapy and for prophylaxis.

  24. TMP-SMX • Excellent tissue penetration. • Produces a rapid clinical response.

  25. DRUG INTERACTIONS • Same as with sulfonamides

  26. RESISTANCE • Results from multiple mechansims. • Altered dihydropteroate synthetase. • Cross-resistance among all sulfonamides.

  27. SULFONAMIDE TRIMETHOPRIM PABA + Pteridine Dihydropteroate Synthetase DIHYDROPTEROIC ACID Dihydrofolate Synthetase DIHYROFOLIC ACID Dihydrofolate Reductase TETRAHYDROFOLIC ACID

  28. ADVERSE EFFECTS • Hypersensitivity reactions -common • allergic rashes • photosensitivity • drug fever • Stevens-Johnson syndrome

  29. CRYSTALLINE AGGREGATES, HEMATURIA, OBSTRUCTION

  30. ADVERSE EFFECTS • Headache, nausea, vomiting and diarrhea. • Hematological effects -anemia, agranulocytosis.

  31. ADVERSE REACTIONS • Dermatological reactions including skin rashes. • GI (nausea and vomiting).

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