sulfasalazine
sulfasalazine.JPG

CLINICAL USE

Ulcerative colitis Crohn’s disease Rheumatoid arthritis

DOSE IN NORMAL RENAL FUNCTION

Oral: 1–2 g 4 times daily, reduced to 0.5 g 4 times dailyEnema: 3 g at night Suppositories: 0.5–1 g twice daily Rheumatoid arthritis: 0.5 g daily, increased to 1.5 g twice daily

PHARMACOKINETICS

  • Molecular weight                           :398.4
  • %Protein binding                           :95–99
  • %Excreted unchanged in urine     : 10–15
  • Volume of distribution (L/kg)       :5.9–9.1
  • half-life – normal/ESRD (hrs)      :18/–

    DOSE IN RENAL IMPAIRMENT

    GFR (mL/MIN)

  • 20 to 50     : Dose as in normal renal function. Use with caution
  • 10 to 20     : Dose as in normal renal function. Use with caution
  • <10           : Start at very low dose and monitor. Use with caution

    DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

  • CAPD                :Unlikely to be dialysed. Dose as in GFR <10 mL/min
  • HD                     :Unlikely to be dialysed. Dose as in GFR <10 mL/min
  • HDF/high flux   :Unlikely to be dialysed. Dose as in GFR <10 mL/min
  • CAV/VVHD      :Unknown dialysability. Dose as in GFR 10 to 20 mL/min

    IMPORTANT DRUG INTERACTIONS

    Potentially hazardous interactions with other drugs
  • Ciclosporin: may reduce ciclosporin levels

    ADMINISTRATION

    Reconstition

    Route

    Oral, rectal

    Rate of Administration

    Comments

    OTHER INFORMATION

    15% of a dose of sulfasalazine is absorbed in the small intestine and becomes highly bound to plasma proteins. The remainder is split into sulfapyridine and 5-ASA by colonic bacteria. Sulfapyridine is rapidly absorbed from the colon, whereas 5-ASA is poorly absorbed
    Most of a dose of sulfasalazine is excreted in the urine. Unchanged sulfasalazine accounts for 15% of the original dose, sulfapyridine and its metabolites 60%, and 5-ASA and its metabolites 20–33%
    Unabsorbed drug is excreted in the faeces In patients with moderate to severe renal impairment, toxicity includes increased risk of crystalluria – ensure high fluid intake



    See how to identify renal failure stages according to GFR calculation

    See how to diagnose irreversible renal disease

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