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: Serial electrocardiographic monitoring may be considered when fluconazole is administered in patients who are at risk for ventricular arrhythmias .
### Output Text:
Serial electrocardiographic monitoring may be considered when <span class="chemical">fluconazole</span> is administered in patients who are at risk for ventricular arrhythmias . 