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: We suggest that caution be taken when cisapride is prescribed with any potent inhibitor of CYP3A4 , including diltiazem .
### Output Text:
We suggest that caution be taken when <span class="chemical">cisapride</span> is prescribed with any potent inhibitor of CYP3A4 , including <span class="chemical">diltiazem</span> . 