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Ketamine can improve morphine analgesia in difficult pain syndromes , such as neuropathic pain .
 Chemical: Ketamine; Chemical: morphine; Disease: pain; Disease: neuropathic pain
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
 Entities: Ketamine, morphine, pain, neuropathic pain 
Answer:
 Chemical: Ketamine; Chemical: morphine; Disease: pain; Disease: neuropathic pain