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: Risperidone , a benzisoxazole derivative antipsychotic , has high serotonin 5 - HT2 receptor blockade and dose - related D2 receptor blockade .
### Output Text:
<span class="chemical">Risperidone</span> , a <span class="chemical">benzisoxazole</span> derivative antipsychotic , has high <span class="chemical">serotonin</span> 5 - HT2 receptor blockade and dose - related D2 receptor blockade . 