Safe Reintroduction of Azathioprine in Behçet's Disease

Assessment and Reintroduction Protocol

The normalization of liver enzymes after a 2-week break suggests a reversible drug effect rather than progressive liver damage, allowing for the safe reintroduction of azathioprine at a lower dose in patients with Behçet's disease 1
Azathioprine can be reintroduced at a significantly reduced dose of approximately 50 mg/day, with gradual dose escalation over 2-3 weeks while monitoring liver function 1
If no reaction occurs after 2-3 days, the dose can be increased sequentially to a target dose that is lower than the previous dose that caused hepatotoxicity, with careful monitoring of liver function tests 1

The European Society of Gastrointestinal Endoscopy recommends monitoring liver function tests twice monthly for the second and third months, then monthly thereafter, to ensure the safe use of azathioprine in patients with Behçet's disease 1, 2
Clinical symptoms such as fatigue, nausea, vomiting, right upper quadrant pain, and jaundice should be monitored, as they may indicate hepatotoxicity 3

Therapy should be stopped if ALT/AST rises to ≥3× baseline or ≥300 U/L with symptoms, or if ALT/AST rises to ≥5× baseline or ≥500 U/L even without symptoms, as recommended by the American Gastroenterological Association 3
If there is any elevation in bilirubin (≥2× ULN) along with elevated transaminases, therapy should be stopped to prevent further liver damage 3

If hepatotoxicity recurs despite dose reduction, alternative immunosuppressive agents such as mycophenolate, tacrolimus, or cyclosporine may be considered for the treatment of Behçet's disease, as suggested by the British Society of Gastroenterology 2

Azathioprine should be reintroduced at a significantly reduced dose (approximately 50 mg/day), with gradual dose escalation over 2-3 weeks while monitoring liver function tests, as recommended by the European Crohn’s and Colitis Organisation 4

Mycophenolate mofetil may be used in azathioprine-intolerant patients, according to the European Society of Gastrointestinal Endoscopy 5
Tacrolimus or cyclosporine may be effective alternatives for patients with azathioprine intolerance, as suggested by the American Gastroenterological Association 5

A repeat liver biopsy should be considered if azathioprine hepatotoxicity is suspected, particularly if it is associated with high blood levels of 6-methylmercaptopurine metabolites, as recommended by the American Association for the Study of Liver Diseases 6
In patients with autoimmune conditions, neither heterozygosity for TPMT nor 6-MP metabolite levels were shown to be reliable predictors of azathioprine efficacy or toxicity, according to the European Association for the Study of the Liver 7