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: Systemic toxicity and resuscitation in bupivacaine - , levobupivacaine - , or ropivacaine - infused rats .
### Output Text:
Systemic toxicity and resuscitation in <span class="chemical">bupivacaine</span> - , <span class="chemical">levobupivacaine</span> - , or <span class="chemical">ropivacaine</span> - infused rats . 