What is Eye drops of sulphonamide are of and explain in detail?
Ans. a (Sulphacetamide). (Ref. Harrison's Medicine 18th/ Chapter 144., KDT 6th/682).........Sulphacetamide eye drops used for ophthalmic neonatorum.The SULFONAMIDES may be classified into 3 groups on the basis of the rapidity with which they are absorbed and excreted: (1) agents that are absorbed and excreted rapidly, such as sulfisoxazole and sulfadiazine: (2) agents that are absorbed very poorly when administered orally and are active in the bowel lumen, such as sulfasalazine: (3) agents that are used topically, such as sulfacetamide, mafenide. and silver sulfadiazine: and (4) long-acting sulfonamides, such as sulfadoxine. that are absorbed rapidly but excreted slowly.SULFONAMIDESRapidly Absorbed And Eliminated SulfonamidesSulfisoxazole.Sulfamethoxazole.Sulfadiazine.Sulfisoxazole is a rapidly absorbed and excreted sulfonamide with excellent antibacterial activity.Since its high solubility eliminates much of the renal toxicity inherent in the use of older sulfonamides, it has essentially replaced the less-soluble agents.Sulfisoxazole is bound extensively to plasma proteins.Sulfisoxazole currently is preferred over other sulfona- mides by when a rapidly absorbed and rapidly excreted sulfonamide is indicated.Sulfamethoxazole is a close congener of sulfisoxazole, but its rates of enteric absorption and urinary excretion are slower.It is administered orally and employed for both systemic and urinary tract infections.Precautions must be observed to avoid sulfamethoxazole crystalluria.The uses of sulfamethoxazole are the same as sulfisoxazole.Sulfadiazine given orally is absorbed rapidly from the GI tract, and peak blood concentrations are reached within 3 to 6 hours after a single dose.About 15% to 40% of the excreted sulfadiazine is in acetylated form. In adults and children who are being treated with sulfadiazine, every precaution must be taken to ensure fluid intake adequate to produce a urine output of at least 1200 ml in adults.Poorly Absorbed Sulfonamides.Sulfasalazine is very poorly absorbed from the Gl tract.It is used in the therapy of ulcerative colitis and regional enteritis, but relapses tend to occur in about one-third of patients who experience a satisfactory initial response.Corticosteroids are more effective in treating acute attacks, but sulfasalazine is preferred to corticosteroids for the treatment of patients who are mildly or moderately ill with ulcerative colitis. The drug also is being employed as the first approach to treatment of relatively mild cases of regional enteritis and granulomatous colitis. Sulfasalazine is broken down by intestinal bacteria to sulfapyridine, an active sulfonamide that is absorbed and eventually excreted in the urine, and 5-aminosalicylate, which reaches high levels in the feces. 5-Aminosalicylate is the effective agent in inflammatory bowel disease, whereas sulfapyridine is responsible for most of the toxicity. Toxic reactions includeHeinz-body anemia, acute hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency, and agranulocytosis. Nausea, fever, arthralgias, and rashes occur in up to 20% of patients treated with the drug; desensitizationhas been an effective treatment. Sulfasalazine can cause a reversible infertility in males owing to changes in sperm number and morphology.Long-Acting Sulfonamides.SulfadoxineIt has a particularly long half-life (7 to 9 days).It is used in combination with pyrimethamine for the prophylaxis and treatment of malaria caused by mefloquine - resistant strains of Plasmodium falciparum.Because of severe and sometimes fatal reactions, including the Stevens-Johnson syndrome, the drug should be used for prophylaxis only where the risk of resistant malaria is high.Sulfonamides for Topical Use.Sulfacetamide.Solutions of the sodium salt of the drug are employed extensively in the management of ophthalmic infections.Although topical sulfonamide for most purposes is discouraged, its advantage is it penetrates into ocular fluids and tissues in high concentration. Sensitivity reactions to sulfacetamide are rare, but the drug should not be used in patients with known hypersensitivity to sulfonamides.Silver sulfadiazine inhibits the growth in vitro of nearly all pathogenic bacteria and fungi, including some species resistant to sulfonamides.The compound is used topically to reduce microbial colonization and the incidence of infections of wounds from burns.It should not be used to treat an established deep infection.Adverse reactions burning, rash, and itching are infrequentMafenide.When applied topically, it is effective for the prevention of colonization of burns by a large variety of gram-negative and grampositive bacteria. It should not be used in deep infection. Superinfection with Candida may be problem. Mafenide is rapidly absorbed systemically and converted to poro-carboxybenzenesulfonamide.Adverse effects include intense pain at sites of application, allergic reactions, and loss of fluid by evaporation from the burn surface because occlusive dressings are not used.Metabolic acidosis with compensatory tachypnea and hyperventilation may ensue; these effects limit its usefulness.