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 report a case of severe hypertension with an occluded renal artery to a solitary kidney , who developed sudden deterioration of renal function following treatment with captopril .
### Output Text:
We report a case of severe hypertension with an occluded renal artery to a solitary kidney , who developed sudden deterioration of renal function following treatment with <span class="chemical">captopril</span> . 