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: Conventional agents are associated with unwanted central nervous system effects , including extrapyramidal symptoms ( EPS ) , tardive dyskinesia , sedation , and possible impairment of some cognitive measures , as well as cardiac effects , orthostatic hypotension , hepatic changes , anticholinergic side effects , sexual dysfunction , and weight gain .
### Output Text:
Conventional agents are associated with unwanted central nervous system effects , including extrapyramidal symptoms ( EPS ) , tardive dyskinesia , sedation , and possible impairment of some cognitive measures , as well as cardiac effects , orthostatic hypotension , hepatic changes , anticholinergic side effects , sexual dysfunction , and weight gain . 