Sulfisoxazole

A to Z Drug Facts

 Action Exerts bacteriostatic action by competing with PABA, an essential component in folic acid synthesis, thus preventing synthesis of folic acid, needed by bacteria for growth.

 Indications

Oral: Treatment of UTI, chancroid, inclusion conjunctivitis, malaria, meningitis caused by Haemophilus influenzae or meningococci, nocardiosis, acute otitis media, toxoplasmosis and trachoma. Ophthalmic: Treatment of conjunctivitis, corneal ulcer and superficial ocular infections, adjunct to systemic sulfonamide therapy of trachoma. unlabeled use(s): Oral: Treatment of recurrent otitis media.

 Contraindications Hypersensitivity to sulfonamides or chemically related drugs (eg, sulfonylureas, thiazide and loop diuretics, carbonic anhydrase inhibitors, sunscreens containing PABA, local anesthetics); hypersensitivity to salicylates; porphyria; children < 2 mo; pregnancy at term.

 Route/Dosage

ADULTS: PO 2 to 4 g initially, then 4 to 8 g/day in 4 to 6 divided doses. Ophthalmic Instill 1 to 2 gtt into lower conjunctival sac q 1 to 3 hr daily. Children & Infants > 2 mo: PO 75 mg/kg initially, then 120 to 150 mg/kg/day in 4 to 6 divided doses (maximum 6 g/day).

 Interactions

Anticoagulants, oral: May enhance anticoagulant action. Cyclosporine: Reduced concentration of cyclosporine and increased risk of toxicity. Hydantoins: May increase hydantoin serum levels. Methotrexate: May enhance risk of methotrexate-induced bone marrow suppression. Sulfonylureas: May increase sulfonylurea half-life and produce hypoglycemia.

 Lab Test Interferences May produce false-positive urinary glucose test results when performed by Benedict's method; may interfere with Urobilistix test; may produce false-positive results with sulfosalicylic acid tests for urinary protein.

 Adverse Reactions

CNS: Headache; peripheral neuropathy; depression; convulsions; dizziness; ataxia. GI: Nausea; vomiting; abdominal pain; diarrhea; anorexia; pancreatitis; impaired folic acid absorption; pseudomembranous enterocolitis. GU: Crystalluria; hematuria; proteinuria; elevated creatinine; nephrotic syndrome; toxic nephrosis with oliguria and anuria. HEPA: Hepatitis; hepatocellular necrosis. HEMA: Agranulocytosis; aplastic anemia; thrombocytopenia; leukopenia; hemolytic anemia; purpura; hypoprothrombinemia; anemia; methemoglobinemia; megaloblastic (macrocytic) anemia. RESP: Pulmonary infiltrates. OTHER: Drug fever; chills; pyrexia; arthralgia; myalgia; periarteritis nodosum; lupus erythematosus phenomenon. Hypersensitivity reactions may present as erythema multiforme of Stevens-Johnson type, generalized skin eruptions, allergic myocarditis, epidermal necrolysis with or without corneal damage, urticaria, serum sickness; pruritus, exfoliative dermatitis, anaphylactoid reactions, periorbital edema, photosensitization, arthralgia and transient pulmonary changes with eosinophilia and decreased pulmonary function. Ophthalmic: Browache; local irritation; transient epithelial keratitis; reactive hyperemia; conjunctival edema; burning; stinging; sensitivity to bright light.

 Precautions

Pregnancy: Category C. Sulfonamides cross placenta and can produce jaundice, hemolytic anemia and kernicterus in newborn; therefore they are contraindicated at term. Lactation: Excreted in breast milk in low concentrations. Do not nurse premature infants or those with hyperbilirubinemia or G-6-PD deficiency. Children: Contraindicated in infants < 2 mo. Allergy or asthma: Use drug with caution in patients with severe allergy or bronchial asthma. Dry eye (ophthalmic): Use with caution in patients with severe dry eye. Group A beta-hemolytic streptococcal infections: Do not use drug for these infections. Hemolytic anemia: May occur in G-6-PD–deficient individuals. Photosensitivity: Photosensitization may occur. Porphyria: Drug may precipitate acute attack of porphyria. Renal or hepatic impairment: Use drug with caution. Severe reactions: Reactions, including deaths, have been associated with hypersensitivity reactions, agranulocytosis, aplastic anemia, other blood dyscrasias and renal and hepatic damage. Irreversible neuromuscular and CNS changes and fibrosing alveolitis may occur. Sulfonamides: Have chemical similarities to some goitrogens, diuretics (acetazolamide and the thiazides) and oral hypoglycemic agents. Goiter production, diuresis and hypoglycemia have occurred rarely in patients receiving sulfonamides. Cross-sensitivity may exist.

 Administration/Storage

Oral Administration

• Give on empty stomach with full glass of water 1 hr before meal or 2 hr after meal for best absorption.
• Administer around clock at equal intervals.
• May crush tablet and mix with liquid for ease of swallowing. May allow patient to chew tablet.
• Shake oral suspension well prior to administration. Measure dose accurately with calibrated device.
• Store oral suspension in refrigerator.

Ophthalmic Solution

• Do not use solution if it is discolored or contains precipitate.
• Wash hands thoroughly before and after instillation.
• Position patient supine or have patient tilt head back in “star-gazing” position (looking at ceiling). Pull down lower lid to form pocket and instill drops as ordered. Avoid contact between dispensing container and eye. Close eye gently and apply pressure to inner canthus for 1 to 2 mins to prevent systemic absorption and draining into nose/throat.
• Store at room temperature and protect from light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note hypersensitivity to salicylates, sulfonamides or chemically related drugs (eg, thiazides, acetazolamide, probenecid); severe hepatic/renal dysfunction; G-6-PD deficiency; porphyria.
• Assess patient for infection (vital signs; appearance of wound, sputum, urine and stool).
• Obtain CBC and culture and sensitivity. First dose may be given before results are available.
• Culture and sensitivity may be repeated when full course of therapy is completed.
• Encourage fluids between meals (up to 2000 ml/day) to maintain hydration and decrease crystallization in kidneys.
• Assess diabetic patients taking oral hypoglycemic agents frequently for hypoglycemia prior to and during therapy.
• Monitor I&O. Note urine color, pH and character.
• Assess skin for rash, bleeding, bruising and jaundice. Note fever, chills, sore throat, mouth sores or joint pain. Report any of these symptoms immediately to physician.

 Patient/Family Education

Oral

• Advise patient to administer medication around clock.
• Advise patient to notify other physicians and dentist of this drug therapy prior to other treatments or surgery.
• Instruct patient to report these symptoms to physician immediately: difficulty breathing, skin rash, fever, chills, mouth sores, sore throat, ringing in ears or unusual bleeding/bruising.
• Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction. Inform patient that photosensitivity may persist for several months after therapy is completed.
• Advise patient not to take otc medications without consulting physician.

Ophthalmic

• Instruct patient/family in correct instillation of drops. Inform patient that stinging, burning and blurred vision may occur after instillation of ophthalmic preparations. Advise patient to avoid hazardous activities until vision clears. Emphasize need for patient to contact physician immediately if patient notices a change in vision, eye pain, increased redness, itching, swelling, loss of sight, inability to breath or flushing after ophthalmic application of this medication.
• Advise patient to note color change or precipitate in container and to discard if these are present.
• Tell patient to notify physician if improvement is not noted within 7 days.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts