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: High doses of inhaled salbutamol produce substantial improvements in airway response in patients with asthma , and are associated with dose - dependent systemic beta - adrenoceptor responses .
### Output Text:
High doses of inhaled <span class="chemical">salbutamol</span> produce substantial improvements in airway response in patients with asthma , and are associated with dose - dependent systemic beta - adrenoceptor responses . 