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 47 - year - old female patient , known to have hypertrophic cardiomyopathy , was admitted with biventricular failure and managed aggressively with dobutamine infusion and other drugs while being assessed for heart transplantation .
### Output Text:
The 47 - year - old female patient , known to have hypertrophic cardiomyopathy , was admitted with biventricular failure and managed aggressively with <span class="chemical">dobutamine</span> infusion and other drugs while being assessed for heart transplantation . 