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: Moderate abnormalities require a reduction of deferoxamine to 25 mg / kg per dose with careful monitoring .
### Output Text:
Moderate abnormalities require a reduction of <span class="chemical">deferoxamine</span> to 25 mg / kg per dose with careful monitoring . 