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: Based upon these results , we conclude that amiodarone disrupts hepatic lipid homeostasis and that the increased expression of PPARalpha target genes is secondary to this toxic effect .
### Output Text:
Based upon these results , we conclude that <span class="chemical">amiodarone</span> disrupts hepatic lipid homeostasis and that the increased expression of PPARalpha target genes is secondary to this toxic effect . 