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: The symptoms occurred around 2 weeks after starting clozapine in an inpatient setting .
### Output Text:
The symptoms occurred around 2 weeks after starting <span class="chemical">clozapine</span> in an inpatient setting . 