Table 1

 Summary of studies of azathioprine/6-mercaptopurine in ulcerative colitis

Author (No of patients)ResultsComments
AZA, azathioprine; 6MP, 6-mercaptopurine; UC, ulcerative colitis; CD, Crohn’s disease; IBD, inflammatory bowel disease.
Randomised, blind, placebo controlled trials
    Jewell1 (n = 80)AZA of no benefit in acute flare compared with placebo (standard steroid course given to all)Some maintenance benefit in preventing relapse in established disease noted.
    Caprilli2 (n = 20)No significant difference between sulphasalazine and AZA in active colitis3 month study. Improvement in symptoms and histology with both drugs.
    Rosenberg5 (30)No clinical or mucosal improvement with AZA after 6 months compared with placebo in chronic UCDose 1.5 mg/kg. Steroid sparing effect noted.
    Kirk3 (n = 44)Significant improvement in chronic UC in AZA group at 3 and 6 monthsSteroid sparing effect noted. No difference in clinical activity scores between AZA and placebo
    Hawthorne6 (79)Relapse at 1 year 36% (AZA) compared with 59% for placeboPlacebo controlled withdrawal study following remission in chronic UC.
    Ardizzone14 (n = 72)Remission at 6 months was 53% for AZA and 21% for 5-aminosalicylic acidAll patients on 40 mg prednisolone at study entry. Steroid sparing effect confirmed. However, investigator blind only. Not double dummy.
Randomised open label studies
    Paoluzi10 (42)69% complete remission of steroid dependant/resistant UC at 6 monthsMethotrexate used if intolerant to AZA. Methotrexate relapse rate found to be less than AZA.
    Sood4 (25)Relapse rate of AZA comparable with sulphasalazine group in the maintenance of remission in severe acute newly diagnosed UC (standard steroid course given to all)Trend towards earlier treatment failure in AZA group.
    Mate-Jimenez13  (72 (34 UC/39 CD))For steroid dependant UC remission rate was 79% for AZA (p<0.05), 58% for methotrexate (NS) compared with 25% for 5ASA.Only comparison of AZA with methotrexate in UC.
Retrospective/case series
    Adler8 (81)63% remission response rate with 6MP in refractory UCIn 48% steroids were eliminated for a mean period of 19 months.
    George9 (105)65% achieved complete and 24% partial clinical remission with 6MPDiscontinuation of 6MP resulted in a higher relapse rate compared with those continuing 6MP.
    Fernandez-Banares19 (10)10% relapse rate with AZA as maintenance over mean of 16 months in this seriesAZA used as maintenance therapy following intravenous ciclosporin in severe acute UC.
    Ardizzone12 (56)69% steroid resistant/dependant UC in remission and off steroids at 3 years with AZAAZA response associated with steroid reduction/elimination, reduced colectomy, and reduced relapse rates.
    Khan7  (111 (53 UC/58 CD))Clinical improvement in 84% of IBD patients at 1 year with AZA, 68% of whom were off steroidsRelatively low dose of AZA 1.5 mg/kg.
    Fraser11  (626 (346 UC/242 CD/4 indeterminate))58% remission rate with AZA for UCRelapse rate similar for UC and CD patients.