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: CONCLUSIONS : The data suggest that neuropsychiatric disorders in PD are more likely an interaction between levodopa and the disease state than a consequence of sensitisation to repeated dopaminergic therapy .
### Output Text:
CONCLUSIONS : The data suggest that neuropsychiatric disorders in PD are more likely an interaction between <span class="chemical">levodopa</span> and the disease state than a consequence of sensitisation to repeated dopaminergic therapy . 