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 describe 4 patients in whom hyperkalemia ranging from 6 . 1 to 6 . 9 mEq / l developed within 3 to 8 days of sulindac administration .
### Output Text:
We describe 4 patients in whom hyperkalemia ranging from 6 . 1 to 6 . 9 mEq / l developed within 3 to 8 days of <span class="chemical">sulindac</span> administration . 