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: The patient developed acute encephalopathy evidenced by behavioral changes , aphasia , incontinence , visual hallucinations , and right - sided weakness with diffuse cerebral vasospasm on magnetic resonance angiography after the administration of intrathecal cytarabine .
### Output Text:
The patient developed acute encephalopathy evidenced by behavioral changes , aphasia , incontinence , visual hallucinations , and right - sided weakness with diffuse cerebral vasospasm on magnetic resonance angiography after the administration of intrathecal <span class="chemical">cytarabine</span> . 