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: Rats were administered fenoldopam for 24 hours by intravenous infusion with or without following repeated daily oral administrations of theophylline .
### Output Text:
Rats were administered <span class="chemical">fenoldopam</span> for 24 hours by intravenous infusion with or without following repeated daily oral administrations of <span class="chemical">theophylline</span> . 