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: However , hepatotoxic events have not been widely published with ezetimibe or the combination agent simvastatin - ezetimibe .
### Output Text:
However , hepatotoxic events have not been widely published with <span class="chemical">ezetimibe</span> or the combination agent <span class="chemical">simvastatin - ezetimibe</span> . 