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: OBJECTIVE : This study determined the antihyperalgesic effect of CNSB002 , a sodium channel blocker with antioxidant properties given alone and in combinations with morphine in rat models of inflammatory and neuropathic pain .
### Output Text:
OBJECTIVE : This study determined the antihyperalgesic effect of <span class="chemical">CNSB002</span> , a <span class="chemical">sodium</span> channel blocker with antioxidant properties given alone and in combinations with <span class="chemical">morphine</span> in rat models of inflammatory and neuropathic pain . 