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: Other causes include drug - related ( cyclosporine , tacrolimus ) toxicity , procoagulant status , and antibody - mediated rejection .
### Output Text:
Other causes include drug - related ( <span class="chemical">cyclosporine</span> , <span class="chemical">tacrolimus</span> ) toxicity , procoagulant status , and antibody - mediated rejection . 