1909
Meperidine - associated central nervous system ( CNS ) excitatory toxicities are believed to be caused by accumulation of the active metabolite normeperidine .
 adverse effect: accumulation of the active metabolite normeperidine, Meperidine; adverse effect: central nervous system ( CNS ) excitatory toxicities, Meperidine
Given options, please tell me the relationships of all the listed entity pairs.Output format is "relation1: word1, word2; relation2: word3, word4". 
Option: adverse effect 
Text: {0} 
 Entity Pairs:  accumulation of the active metabolite normeperidine, Meperidine; central nervous system ( CNS ) excitatory toxicities, Meperidine 
Answer:
 adverse effect: accumulation of the active metabolite normeperidine, Meperidine; adverse effect: central nervous system ( CNS ) excitatory toxicities, Meperidine