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: This suggests that benztropine is not the anticholinergic drug of choice in the treatment of neuroleptic - induced parkinsonian symptoms , because of its more toxic central and peripheral atropinic effect .
### Output Text:
This suggests that <span class="chemical">benztropine</span> is not the anticholinergic drug of choice in the treatment of neuroleptic - induced parkinsonian symptoms , because of its more toxic central and peripheral atropinic effect . 