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: Continuous subcutaneous apomorphine infusions can reduce daily off - time by more than 50 % in this group of patients , which appears to be a stronger effect than that generally seen with add - on therapy with oral dopamine agonists or COMT inhibitors .
### Output Text:
Continuous subcutaneous <span class="chemical">apomorphine</span> infusions can reduce daily off - time by more than 50 % in this group of patients , which appears to be a stronger effect than that generally seen with add - on therapy with oral <span class="chemical">dopamine</span> agonists or COMT inhibitors . 