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: One commenced the closely related drug amlodipine 3 years later , with recurrence of telangiectasia .
### Output Text:
One commenced the closely related drug <span class="chemical">amlodipine</span> 3 years later , with recurrence of telangiectasia . 