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: Moreover , treatment with the kinin B2 receptor antagonist effectively reduced the levels of serum creatinine and blood urea after cisplatin administration .
### Output Text:
Moreover , treatment with the kinin B2 receptor antagonist effectively reduced the levels of serum <span class="chemical">creatinine</span> and blood <span class="chemical">urea</span> after <span class="chemical">cisplatin</span> administration . 