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: CASE SUMMARIES : A 54 - year - old woman with hyperaldosteronism was treated with verapamil 480 mg / d and spironolactone 100 mg / d .
### Output Text:
CASE SUMMARIES : A 54 - year - old woman with hyperaldosteronism was treated with <span class="chemical">verapamil</span> 480 mg / d and <span class="chemical">spironolactone</span> 100 mg / d . 