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: In both cases normal plasma and urinary free cortisol levels had been achieved following ketoconazole therapy , yet continuous blood pressure monitoring demonstrated hypertension 31 ( patient 1 ) and 52 weeks ( patient 2 ) after treatment .
### Output Text:
In both cases normal plasma and urinary free <span class="chemical">cortisol</span> levels had been achieved following <span class="chemical">ketoconazole</span> therapy , yet continuous blood pressure monitoring demonstrated hypertension 31 ( patient 1 ) and 52 weeks ( patient 2 ) after treatment . 