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 urinary output should be monitored and the oxytocin administration discontinued and the serum electrolytes checked if the urinary output decreases .
### Output Text:
The urinary output should be monitored and the <span class="chemical">oxytocin</span> administration discontinued and the serum electrolytes checked if the urinary output decreases . 