SULFASALAZINE

SULFASALAZINE
(sul-fa-sal'a-zeen)
Azulfidine, PMS Sulfasalazine , PMS Sulfasalazine E.C. , Salazopyrin , SAS Enteric-500 , S.A.S.-500 
Classifications: mucous membrane agent; antiinflammatory; sulfonamide;
Therapeutic: gi antiinflammatory
; immunomodulatory; disease-modifying antirheumatic drug (dmard)
Prototype: Mesalamine
Pregnancy Category: B

Availability

500 mg tablets; 500 mg sustained release tablets

Action

Locally acting sulfonamide. Believed to be converted by intestinal microflora to sulfapyridine (provides antibacterial action) and 5-aminosalicylic acid (5-ASA) or mesalamine, which may exert an antiinflammatory effect. Proposed mechanisms of action include inhibition of prostaglandins known to cause diarrhea and affect mucosal transport and interference with absorption of fluids and electrolytes from colon.

Therapeutic Effect

Reduces Clostridium and Escherichia coli in the stools. Antiinflammatory and immunomodulatory properties are effective in controlling the S&S of ulcerative colitis and rheumatoid arthritis.

Uses

Ulcerative colitis and relatively mild regional enteritis; rheumatoid arthritis.

Unlabeled Uses

Granulomatous colitis, Crohn's disease, scleroderma.

Contraindications

Sensitivity to sulfasalazine, other sulfonamides and salicylates; carbonic anhydrase inhibitors, thiazide diuretics; agranulocytosis; children <2 y; intestinal and urinary tract obstruction; porphyria.

Cautious Use

Severe allergy, or bronchial asthma; blood dyscrasias; hepatic or renal impairment; G6PD deficiency; older adults; pregnancy (category B); lactation; children <6 y.

Route & Dosage

Ulcerative Colitis, Rheumatoid Arthritis
Adult: PO 1–2 g/d in 4 divided doses, may increase up to 8 g/d if needed
Child: PO 40–50 mg/kg/d in 4 divided doses (max: 75 mg/kg/d)

Juvenile Rheumatoid Arthritis
Child: PO 10 mg/kg/d, increase weekly by 10 mg/kg/d [usual dose: 15–25 mg/kg q12h (max: 2 g/d)]

Administration

Oral
  • Give after eating to provide longer intestine transit time.
  • Do not crush or chew sustained release tablets; must be swallowed whole.
  • Use evenly divided doses over each 24-h period; do not exceed 8-h intervals between doses.
  • Consult physician if GI intolerance occurs after first few doses. Symptoms are probably due to irritation of stomach mucosa and may be relieved by spacing total daily dose more evenly over 24 h or by administration of enteric-coated tablets.
  • Store at 15°–30° C (59°–86° F) in tight, light-resistant containers.

Adverse Effects (≥1%)

Body as a Whole: Nausea, vomiting, bloody diarrhea; anorexia, arthralgia, rash, anemia, oligospermia (reversible), blood dyscrasias, liver injury, infectious mononucleosis–like reaction, allergic reactions.

Interactions

Drug: Iron, antibiotics may alter absorption of sulfasalazine.

Pharmacokinetics

Absorption: 10–15% from GI tract unchanged; remaining drug is hydrolyzed in colon to sulfapyridine (most of which is absorbed) and 5-aminosalicylic acid (30% of which is absorbed). Peak: 1.5–6 h sulfasalazine; 6–24 h sulfapyridine. Distribution: Crosses placenta; distributed into breast milk. Metabolism: In intestines and liver. Elimination: All metabolites are excreted in urine. Half-Life: 5–10 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor for GI distress. GI symptoms that develop after a few days of therapy may indicate need for dosage adjustment. If symptoms persist, physician may withhold drug for 5–7 d and restart it at a lower dosage level.
  • Be aware that adverse reactions generally occur within a few days to 12 wk after start of therapy; most likely to occur in patients receiving high doses (4 g or more).
  • Lab tests: Measure RBC folate in patients on high doses (more than 2 g/d); a daily supplement may be prescribed.

Patient & Family Education

  • Examine stools and report to physician if enteric-coated tablets have passed intact in feces. Some patients lack enzymes capable of dissolving coating; conventional tablet will be ordered.
  • Be aware that drug may color alkaline urine and skin orange-yellow.
  • Remain under close medical supervision. Relapses occur in about 40% of patients after initial satisfactory response. Response to therapy and duration of treatment are governed by endoscopic examinations.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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