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 antifibrinolytic agent has been used in women with menorrhagia to promote clotting and reduce blood loss .
### Output Text:
This antifibrinolytic agent has been used in women with menorrhagia to promote clotting and reduce blood loss . 