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: There was a statistically longer time to first episode of nausea ( P = . 0015 ) and vomiting ( P = . 0001 ) , and fewer patients were administered additional antiemetic medication in the 10 - micrograms / kg dosing groups than in the 5 - micrograms / kg dosing group .
### Output Text:
There was a statistically longer time to first episode of nausea ( P = . 0015 ) and vomiting ( P = . 0001 ) , and fewer patients were administered additional antiemetic medication in the 10 - micrograms / kg dosing groups than in the 5 - micrograms / kg dosing group . 