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: Five months after starting nifedipine ( Adalat ) , two patients developed photodistributed facial telangiectasia , which became more noticeable with time .
### Output Text:
Five months after starting <span class="chemical">nifedipine</span> ( <span class="chemical">Adalat</span> ) , two patients developed photodistributed facial telangiectasia , which became more noticeable with time . 