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: Thus , dronedarone and amiodarone displayed a similar level of antiadrenergic effect and did not impair the resting left ventricular function .
### Output Text:
Thus , <span class="chemical">dronedarone</span> and <span class="chemical">amiodarone</span> displayed a similar level of antiadrenergic effect and did not impair the resting left ventricular function . 