. ▁ ▁These ▁in hib itors ▁include ▁az ath iop r ine , ▁an ▁imm unos upp ress ant ▁used ▁in ▁organ ▁trans plant ation , ▁auto imm une ▁disease ▁such ▁as ▁r he um ato id ▁ar th rit is ▁or ▁infl am mat ory ▁bow el ▁disease ▁such ▁as ▁Cro hn ' s ▁disease ▁and ▁ul cer ative ▁col itis . ▁ ▁My c oph en olate ▁m of et il ▁is ▁an ▁imm unos upp ress ant ▁drug ▁used ▁to ▁prevent ▁re jection ▁in ▁organ ▁trans plant ation ; ▁it ▁in hib its ▁pur ine ▁synth esis ▁by ▁blocking ▁in os it ol ▁mon oph osph ate ▁de h ydro gen ase . ▁Also ▁M eth ot re x ate ▁indirect ly ▁in hib its ▁pur ine ▁synth esis ▁by ▁blocking ▁the ▁met abol ism ▁of ▁fol ic ▁acid ▁( it ▁is ▁an ▁in hib itor ▁of ▁the ▁di h ydro fol ate ▁re duct ase ). ▁ ▁Al lop ur in ol ▁is ▁a ▁drug ▁that ▁in hib its ▁the ▁en zym e ▁x anth ine ▁ox id ored uct ase ▁and , ▁thus , ▁low ers ▁the ▁level ▁of ▁u ric ▁acid ▁in ▁the ▁body . ▁This ▁may ▁be ▁useful ▁in ▁the ▁treatment ▁of ▁g out , ▁which ▁is ▁a ▁disease ▁caused ▁by ▁excess ▁u ric ▁acid , ▁forming ▁cry st als ▁in ▁joint s . ▁ ▁See ▁also ▁▁ ▁Pur iner g ic ▁signal ing ▁ ▁D ise ase - mod ifying ▁ant ir he um atic