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Given that discontinuation of nitrofurantoin and introduction of methylprednisolon therapy significantly lowered liver enzyme levels, restoring most of them to normal, we concluded that this was probably the case of toxic liver damage caused by nitrofurantoin.
 ( adverse event: caused ,  toxic liver damage: Effect, nitrofurantoin: Treatment, nitrofurantoin: Treatment.Drug) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( adverse event: caused ,  toxic liver damage: Effect, nitrofurantoin: Treatment, nitrofurantoin: Treatment.Drug) 