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: We review previous reports linking RPN to antiinflammatory drug use and discuss possible advantages of sulindac in patients who have experienced renal toxicity from other antiinflammatory agents .
### Output Text:
We review previous reports linking RPN to antiinflammatory drug use and discuss possible advantages of <span class="chemical">sulindac</span> in patients who have experienced renal toxicity from other antiinflammatory agents . 