Sulfonamides
Sulfonamides
Sulfonamides are antibiotics. They are bacteriostatic; competitively antagonize paraaminobenzoic acid, an essential component of folic acid synthesis, in susceptible gramnegative and gram-positive bacteria, causing cell death.
Indications
Treatment of ulcerative colitis, otitis media, inclusion conjunctivitis, meningitis, nocardiosis, toxoplasmosis, trachoma, UTIs Management of rheumatoid arthritis, collagenous colitis, Crohn’s disease Contraindications and cautions
Contraindicated with allergy to sulfonamides, sulfonylureas, thiazides; pregnancy (teratogenic in preclinical studies; at term, may bump fetal bilirubin from plasma protein–binding sites and cause kernicterus); or lactation (risk of kernicterus, diarrhea, rash). Use cautiously with impaired renal or hepatic function, G6PD deficiency, porphyria. Adverse effects
CNS: Headache, peripheral neuropathy, mental depression, seizures, ataxia, hallucinations, tinnitus, vertigo, insomnia, hearing loss, drowsiness, transient lesions of posterior spinal column, transverse myelitis Dermatologic: Photosensitivity, cyanosis, petechiae, alopecia GI: Nausea, emesis, abdominal pains, diarrhea, bloody diarrhea, anorexia, pancreatitis, stomatitis, impaired folic acid absorption, hepatitis, hepatocellular necrosis GU: Crystalluria, hematuria, proteinuria, nephrotic syndrome, toxic nephrosis with oliguria and anuria, oligospermia, infertility Hematologic: Agranulocytosis, aplasticanemia,thrombocytopenia, leukopenia, hemolytic anemia, hypoprothrombinemia, methemoglobinemia, megaloblastic anemia Hypersensitivity: Stevens-Johnson syndrome,generalized skin eruptions, epidermal necrolysis, urticaria, serum sickness, pruritus, exfoliative dermatitis, anaphylactoid reactions,periorbital edema, conjunctival and scleral redness, photosensitization, arthralgia, allergic myocarditis, transient pulmonary changes with eosinophilia, decreased pulmonary function Other: Drug fever, chills, periarteritis nodosum Interactions
Drug-drug Increased risk of hypoglycemia when tolbutamide, tolazamide, glyburide, glipizide, chlorpropamide are taken concurrently Increased risk of folate deficiency if taking sulfonamides; monitor patients receiving folic acid carefully for signs of folate deficiency
Drug-lab test Possible false-positive urinary glucose tests using Benedict’s method Nursing considerations
Assessment
History: Allergy to sulfonamides, sulfonylureas, thiazides; pregnancy; lactation; impaired renal or hepatic function; G6PD deficiency; porphyria Physical: T; skin color, lesions; culture of infected site; orientation, reflexes, affect, peripheral sensation; R, adventitious sounds; mucous membranes, bowel sounds, liver evaluation; LFTs, renal function tests, CBC and differential, urinalysis Interventions
Arrange for culture and sensitivity tests of infected area prior to therapy; repeat cultures if response is not as expected. Administer drug after meals or with food to prevent GI upset. Administer the drug around the clock. Adverse effects
in italics are most common; those in bold are life-threatening. U Do not crush. Ensure adequate fluid intake. Discontinue drug immediately if hypersensitivity reaction occurs. Establish safety precautions if CNS effects occur (side rails, assistance, environmental control). Protect patient from exposure to light (use sunscreen, protective clothing) if photosensitivity occurs. Provide frequent small meals if GI upset occurs. Provide mouth care for stomatitis. Offer support and encouragement to deal with side effects of drug therapy, including changes in sexual function. Teaching points
Complete the full course of therapy. Take these drugs with food or meals to decrease GI upset. Drink eight glasses of water per day. These drugs are specific to the disease being treated; do not use to self-treat any other infection. You may experience these side effects: Sensitivity to sunlight (use sunscreens; wear protective clothing); dizziness, drowsiness, difficulty walking, loss of sensation (avoid driving or performing tasks that require alertness); nausea, vomiting, diarrhea (ensure ready access to bathroom); loss of fertility; yellow-orange urine. Report blood in the urine, rash, ringing in the ears, difficulty breathing, fever, sore throat, chills. Representative drugs
balsalazide sulfadiazine sulfamethoxazole (always used in combination with trimethoprim) sulfasalazine sulfisoxazole
