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Sulfasalazine is a synthetic salicylic acid derivative with an affinity for connective tissue containing 
elastin and formulated as a prodrug , antiinflammatory Sulfasalaine acts locally in the intestine 
through its active metabolite , sulfamide 5-aminosalicylic acid and salicylic acid , by a mechanism
 that is not clear ( Pubchem )

Salazopyrin En-Tabs 500 mg tablets also comes with Enteric coating to reduce GI SEs Typical regimen may start with 500 mg / day ↑ ed at intervals of 1 week by one 500 mg tablet a day to a max of 2-3 gm in divided doses

Ulcerative Colitis -induction and maintenance of remission Crohn’s disease – treatment Rheumatoid arthritis Sero negative spondylo-arthopathy ( including psoriatic arthritis and Psoriasis ) Can be used as monotherapy or in combination

Is a prodrug Structurally related to both salicylates ( for eg aspirin ) and sulphonamides Split by bacterial in colon into Sulfapyridine ( SP ) & Mesalazine MP ) Precise mechanism of action not know Local actions of mesalamine in colon – likely reason for effectiveness in inflammatory bowel dis RA- may be related to anti-inflammatory and immunomodulatory properties In rheumatoid arthritis a disease-modifying effect is seen in 1-3 months ( reduction in inflammatory markers ) Renal/Faecal- primary excretion routes

Adverse effects

Adverse reactions are possible to either Suphonamide or Salicylate Most commonly encountered are nausea , headache , rash , loss of appetite and raised temperature

Few other points
 May discolour contact lenses ( yellow/ orange ) Can cause a fall in sperm count- leading to a reversible temporary decrease in male fertility Pregnancy- can be used not teratogenic Breast feeding – small amounts in milk ( risk neonatal haemolysis ) Patients with known ANA→ can induce lupus like illness G6PD ( glucose -6-phosphate dehydrogenase ) risk haemolytic anaemia

Digoxin- reduced absorption Hypoglycaemia risk ( if on hypoglycaemic agents ) Increased GI adverse effects -particularly nausea if used with Methotrexate Azathioprine / Mercaptopurine →bone marrow suppression and leucopenia

Monitoring- FBC or CBC Fortnightly for the 1st 3 months Monthly for 2nd 3 months 3 monthly or as clinically indicated after that WBC < 3.5 x 109 / L Neutrophils < 2 x 109 / L
( threshold may vary locally from
1.5 to 2 check with local team ) Platelets < 150 x 109 / L

 MCV > 105 fL 
○ check Vit B12 and TSH
○ If abnormal treat underlying abnormality
○ If normal discuss with specialist team Withhold treatment until discussed with specialist team

LFT Fortnightly for the 1st 3 months Monthly for 2nd 3 months 3 monthly or as clinically indicated after that AST , ALT → twice upper limit of normal Withold treatment until discussed with specialist team

us and Es Renal function test Urinalysis Monthly for 1st 3 months As clinically indicated after that Excreted in urine and accumlation is associated with ↑risk of toxicity 

Check for presence of rash or oral ulceration
( each visit )
 Nausea / dizziness / headache

 Abnormal bruising , pallor , severe sore throat , fever malaise

 Unexplained acute widespread rash

 Oral ulceration



Versus arthritis on sulfasalazine – a well written 8 page leaflet

Australian Rheumatology Association

Medline Plus on Sulfasalazine

Medicine compendium on sulfasalazine

American College of Rheumatology on Sulfasalazine

Alberta rheumatology -concise PIL

A balanced well written informative page for patients from Health Navigator New Zealand



A review article on DMARD monitoring Rigby WFC, Lampl K, Low JM, Furst DE. Review of Routine Laboratory Monitoring for Patients with Rheumatoid Arthritis Receiving Biologic or Nonbiologic DMARDsInt J Rheumatol. 2017;2017:9614241. doi:10.1155/2017/9614241

Another article on DMARD monitoring from BPAC NZ

FDA on sulfasalazine a 21-page document

Use of sulfasalazine in dermatology from DermNet Nz

A complete resource on sulfasalazine from PDR Net

Drugbank database on sulfasalazine

References ;

  1.  BSR/ BHPR guideline for disease-modifying anti-rheumatic drug ( DMARD ) therapy in consultation with the British Association of Dermatologists K Chakravarty et al Rhematology 2008 ; 1 of 16
  2. Gwent Shared Care Protocol Sulfasalazine for Rheumatoid Arthritis ABHB
  3. Drugbank accessed via
  4. CKS NKS accessed via!scenario:11
  5. Shropshire Clinical Commissioning Group
  6. Wirral University Teaching Hospitals










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