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: Both drugs were immediately discontinued , and the patient recovered after subsequent nicardipine and verapamil treatment .
### Output Text:
Both drugs were immediately discontinued , and the patient recovered after subsequent <span class="chemical">nicardipine</span> and <span class="chemical">verapamil</span> treatment . 