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: Prompt restoration of renal function followed drug withdrawal , while re - exposure to a single dose of indomethacin caused recurrence of acute reversible oliguria .
### Output Text:
Prompt restoration of renal function followed drug withdrawal , while re - exposure to a single dose of <span class="chemical">indomethacin</span> caused recurrence of acute reversible oliguria . 