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: The emergency physician should be aware that life - threatening tetany may accompany the administration of intravenous diltiazem and that calcium chloride may be a rapid and effective remedy .
### Output Text:
The emergency physician should be aware that life - threatening tetany may accompany the administration of intravenous <span class="chemical">diltiazem</span> and that <span class="chemical">calcium chloride</span> may be a rapid and effective remedy . 