Sulfonamides

Sulfonamides are bacteriostatic antibiotics.

They include:

• Sulfamethoxazole (Mostly combined with trimethoprim)
• Sulfadiazine
• Sulfisoxazole
• Sulfasalazine
• Balsalazide

Pregnancy Category: C (and D at term)

They can be used in life-threatening conditions when there are no safer drugs. Studies have shown that they have potential risks to fetal life. They may increase the levels of unconjugated bilirubin and cause kernicterus in a baby at term.

Mechanism of Action

They inhibit the synthesis of folic acid in susceptible organisms, causing cell death.

Indications

• Used in the treatment of otitis media, conjunctivitis, meningitis, trachoma, ulcerative colitis, toxoplasmosis, and urinary tract infections.
• Used in the management of Crohn’s disease and rheumatoid arthritis.

Cautions and Contraindications

• Use cautiously in impaired renal and hepatic function and G6PD deficiency.
• Contraindicated in patients allergic to sulfa drugs, sulfonylureas, and thiazides; and in pregnancy and lactation

Adverse Effects

• Hypersensitivity: Stevens-Johnson syndrome, exfoliative dermatitis, anaphylaxis, urticaria, pruritus
• Nervous system: Headache, depression, seizures, vertigo, insomnia, hearing loss, drowsiness, tinnitus, photosensitivity
• Dermatological: Cyanosis, petechiae, alopecia
• Gastrointestinal system: Nausea, vomiting, abdominal pains, diarrhea, anorexia, impaired folic acid absorption
• Genitourinary: Hematuria, proteinuria, nephrotic syndrome, oligospermia, and infertility
• Hematologic: Agranulocytosis, aplastic anemia, hemolytic anemia, thrombocytopenia, and megaloblastic anemia

Interactions

• There is an increased risk of hypoglycemia when they are taken concurrently with chlorpropamide, tolbutamide, and glipizide.
• Impairs folic acid absorption and may lead to folate deficiency.

Nursing Implications

Assessment

• Assess for any allergic reactions to sulfa drugs, sulfonylureas, and thiazides
• Assess for pregnancy and lactation
• Assess for renal and hepatic function and G6PD deficiency
• Assess the hydration status of the patient

Interventions

• Before therapy, obtain culture for and sensitivity.
• Administer the drug around the clock; during or after meals to prevent GI disturbances.
• If CNS effects or photosensitivity occur, establish safety measures to prevent further harm.
• Ensure that the patient is well hydrated.
• If hypersensitivity occurs, discontinue therapy.
• Help the patient deal with the side effects of therapy and offer encouragement.

Patient/Family Teaching

• Advise the patient to take at least 8 glasses (2 liters) of water per day.
• Instruct the patient to finish the full course of therapy.
• Instruct the patient to take drugs with food or meals to decrease GI upset
• Advise the patient against self-medication with the drugs.
• Teach about side effects including sensitivity to light, dizziness, drowsiness, yellow-orange urine, and loss of fertility among others
• Report blood in urine, ringing ears, breathing difficulty, fever, sore throat, and chills

References

• Karch M. (2014). Lippincott’s Nursing Drug Guide.Wolter’s Kluwer/Lippincott Williams and Wilkins. New York, USA.
• Vallerand A., Sanoski C., Deglin J. (2015). Davis’s Drug Guide for Nurses (14^th Ed). F.A Davis Company. Philadelphia, Pennsylvania, USA.
• Whalen K., Finkel R., Panavelil T. (2015). Lippincott Illustrated Reviews Pharmacology (6^th Ed). Wolter’s Kluwer. USA.