In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: RESULTS : amiodarone use was associated with an increased risk of pacemaker insertion ( OR : 2 . 14 , 95 % confidence interval [ CI ] : 1 . 30 to 3 . 54 ) .
### Output Text:
RESULTS : <span class="chemical">amiodarone</span> use was associated with an increased risk of pacemaker insertion ( OR : 2 . 14 , 95 % confidence interval [ CI ] : 1 . 30 to 3 . 54 ) . 