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: It was concluded that treatment with enalapril was well tolerated and it is , therefore , unreasonable to restrict the initiation of treatment with enalapril to inpatients .
### Output Text:
It was concluded that treatment with <span class="chemical">enalapril</span> was well tolerated and it is , therefore , unreasonable to restrict the initiation of treatment with <span class="chemical">enalapril</span> to inpatients . 