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: After the end of fenoterol - hydrobromide infusion , tremor amplitudes decreased significantly faster than those following ritodrin - HCl infusion .
### Output Text:
After the end of <span class="chemical">fenoterol - hydrobromide</span> infusion , tremor amplitudes decreased significantly faster than those following <span class="chemical">ritodrin - HCl</span> infusion . 