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: Indomethacin , 1 - 10 mg / kg , and ibuprofen , 10 - 100 mg / kg , failed to modulate seizures produced by pilocarpine .
### Output Text:
<span class="chemical">Indomethacin</span> , 1 - 10 mg / kg , and <span class="chemical">ibuprofen</span> , 10 - 100 mg / kg , failed to modulate seizures produced by <span class="chemical">pilocarpine</span> . 