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: On the 10th day of paroxetine and alprazolam treatment , the patient exhibited marked psychomotor retardation , disorientation , and severe muscle rigidity with tremors .
### Output Text:
On the 10th day of <span class="chemical">paroxetine</span> and <span class="chemical">alprazolam</span> treatment , the patient exhibited marked psychomotor retardation , disorientation , and severe muscle rigidity with tremors . 