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 treatment with octreotide , 17 patients developed sludge , 10 had gallstones , and 1 developed acute cholecystitis requiring surgery .
### Output Text:
During treatment with <span class="chemical">octreotide</span> , 17 patients developed sludge , 10 had gallstones , and 1 developed acute cholecystitis requiring surgery . 