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 the absence of amiodarone therapy , a second bladder irrigation did not induce TdP despite hypokalemia and hypomagnesemia .
### Output Text:
In the absence of <span class="chemical">amiodarone</span> therapy , a second bladder irrigation did not induce TdP despite hypokalemia and hypomagnesemia . 