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Animals were administered nicotine , carbachol , or neostigmine via timed tail vein infusion , and the latencies to onset of tremor and clonus were recorded and converted to threshold dose .
 nicotine, carbachol, neostigmine, tremor
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 nicotine, carbachol, neostigmine, tremor