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: This drug caused biventricular dysfunction , due to its negative inotropic effect , and hypotension , due to its peripheral vasodilatory effect .
### Output Text:
This drug caused biventricular dysfunction , due to its negative inotropic effect , and hypotension , due to its peripheral vasodilatory effect . 