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: Oxytocin administration during midtrimester - induced abortions is advocated only if it can be carried out under careful observations of an alert nursing staff , aware of the symptoms of water intoxication and instructed to watch the diuresis and report such early signs of the syndrome as asthenia , muscular irritability , or headaches .
### Output Text:
<span class="chemical">Oxytocin</span> administration during midtrimester - induced abortions is advocated only if it can be carried out under careful observations of an alert nursing staff , aware of the symptoms of water intoxication and instructed to watch the diuresis and report such early signs of the syndrome as asthenia , muscular irritability , or headaches . 