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 , benztropine treated patients had a significant increase in tardive dyskinesia compared to their condition during procyclindine treatment , and significantly more anxiety and depression than ethopropazine treated patients .
### Output Text:
However , <span class="chemical">benztropine</span> treated patients had a significant increase in tardive dyskinesia compared to their condition during <span class="chemical">procyclindine</span> treatment , and significantly more anxiety and depression than <span class="chemical">ethopropazine</span> treated patients . 