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Attempts were made to stop and then restart the theophylline therapy at progressively lower doses ; however , with each attempt , the patient 's reaction to the drug became more toxic , with serum theophylline levels ranging between 99.9 and 149.9 micromol / L ( 18 and 27 microg / mL ) .
 reaction to the drug became more toxic, theophylline; reaction to the drug became more toxic, theophylline
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 reaction to the drug became more toxic, theophylline; reaction to the drug became more toxic, theophylline