2564
Two patients who were receiving Tolazoline by infusion developed duodenal ulceration and subsequent intestinal perforation.
 ( adverse event: developed ,  Two patients: Subject, Two: Subject.Population, duodenal ulceration and subsequent intestinal perforation: Effect, receiving Tolazoline by infusion: Treatment, Tolazoline: Treatment.Drug, infusion: Treatment.Route) 
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: developed ,  Two patients: Subject, Two: Subject.Population, duodenal ulceration and subsequent intestinal perforation: Effect, receiving Tolazoline by infusion: Treatment, Tolazoline: Treatment.Drug, infusion: Treatment.Route) 