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: During the first 5 mo , 596 patients received aprotinin ( Group A ) ; in the next 5 mo , 592 patients were treated with tranexamic acid ( Group T ) .
### Output Text:
During the first 5 mo , 596 patients received aprotinin ( Group A ) ; in the next 5 mo , 592 patients were treated with <span class="chemical">tranexamic acid</span> ( Group T ) . 