Other purine analogues, such as allopurinol, inhibit xanthine oxidase, the enzyme that breaks down<unk> , thus increasing the toxicity of<unk> . Low doses of allopurinol, though, have been shown to safely enhance the efficacy of<unk> , especially in inflammatory bowel disease nonresponders. This may still lead to lower lymphocyte counts and higher rates of infection, therefore the combination requires careful monitoring.<unk>  decreases the effects of the anticoagulant warfarin and of nondepolarizing muscle relaxants, but increases the effect of depolarizing muscle relaxants. It can also interfere with niacin (vitamin B3), resulting in at least one case to pellagra and fatal medullary aplasia.
Azathioprine
Hydroxychloroquine
Etanercept
Aminophenazone
Tofacitinib
Teriflunomide
Leflunomide
Sirolimus