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: In addition , subcutaneous delivery of the neutralizing agent will not be associated with the risk of inadequate urinary mesna concentrations , such as in a patient taking oral mesna who experiences severe ifosfamide - induced emesis and is unable to absorb the drug .
### Output Text:
In addition , subcutaneous delivery of the neutralizing agent will not be associated with the risk of inadequate urinary <span class="chemical">mesna</span> concentrations , such as in a patient taking oral <span class="chemical">mesna</span> who experiences severe <span class="chemical">ifosfamide</span> - induced emesis and is unable to absorb the drug . 