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: If confirmed , this may be important because most Indian patients receive the cheaper older sulphonylureas , and present guidelines do not distinguish between individual agents .
### Output Text:
If confirmed , this may be important because most Indian patients receive the cheaper older <span class="chemical">sulphonylureas</span> , and present guidelines do not distinguish between individual agents . 