Sulfonamides

15

Summary

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Key Points

  • Sulfonamides
    • Key Drugs (Sulfa-)
      • Do not confuse with sulfonylureas - drug class used to treat type II diabetes (e.g. glipizide, glyburide). They are also a sulfa- derivative, but are used for a different purpose.
      • Sulfamethoxazole (SMX)
        • Often combined with another antibacterial agent, trimethoprim (TMP) into TMP-SMX, commonly known as Bactrim
      • Sulfadiazine
      • Sulfasalazine (SSZ) - used as an auto-immune drug
    • Mechanism
      • Antibiotic
        • Inhibit synthesis of folic acid, an essential component of bacterial growth
        • Bacteriostatic
    • Clinical Use
      • Bacterial Infections
        • Urinary tract infections
        • Ear infections
        • Meningococcal meningitis
        • E. coli
        • MRSA
        • Used as an alternative for patients allergic to penicillin
    • Side Effects and Adverse Reactions
      • Hypersensitivity/Allergy
        • Cross-allergenicity with other sulfa drugs (e.g. sulfonylureas and thiazide diuretics)
      • Crystalluria
        • Crystallization in the urine
        • Can cause kidney injury
        • Increase fluid intake to maintain adequate urine output
          • Ideally, patient should be consuming at least 2,000 mL/day
          • Increased hydration reduces the risk of crystal formation
      • Photosensitivity
        • Avoid direct sunlight, wear sunscreen and protective clothing during sun exposure
        • May escalate into Stevens-Johnson Syndrome / Toxic Epidermal Necrolysis
          • If rash presents, patient should stop taking medication and it should be reported immediately to the provider
      • Folate deficiency
        • Folic acid supplementation may be needed
      • Teratogenic
        • Should be avoided in pregnancy
        • Can cause neural tube defects and infantile kernicterus, especially if taken in the 3rd trimester
      • Red-orange discoloration of body fluids
      • Anemia, agranulocytosis, low platelet count
        • Due to a reduction in folic acid
        • Report bruising, bleeding, petechial rash
      • Hemolysis is especially common in G6PD deficiency
      • Superinfection
        • e.g. C. difficile overgrowth
      • GI disturbances
        • Nausea, vomiting, anorexia