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: On the 49th day of terbinafine therapy , he was brought to the emergency room for a decrease of his global health status , confusion and falls .
### Output Text:
On the 49th day of <span class="chemical">terbinafine</span> therapy , he was brought to the emergency room for a decrease of his global health status , confusion and falls . 