sulfasalazine
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)       :5.9–9.1half-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/minHDF/high flux   :Unlikely to be dialysed. Dose as in GFR <10 mL/minCAV/VVHD      :Unknown dialysability. Dose as in GFR 10 to 20 mL/min IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugsCiclosporin: 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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