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: Hyperkalemia induced by indomethacin and naproxen and reversed by fludrocortisone .
### Output Text:
Hyperkalemia induced by <span class="chemical">indomethacin</span> and <span class="chemical">naproxen</span> and reversed by <span class="chemical">fludrocortisone</span> . 