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: Discontinuation of azithromycin and therapy with baclofen finally resolved hiccups .
### Output Text:
Discontinuation of <span class="chemical">azithromycin</span> and therapy with <span class="chemical">baclofen</span> finally resolved hiccups . 