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 doses calculated to cause 50 % reversal of hyperalgesia ( ED50 ) were 7 . 54 ( 1 . 81 ) and 4 . 83 ( 1 . 54 ) in the carrageenan model and 44 . 18 ( 1 . 37 ) and 9 . 14 ( 1 . 24 ) in the STZ - induced neuropathy model for CNSB002 and morphine , respectively ( mg / kg ; mean , SEM ) .
### Output Text:
The doses calculated to cause 50 % reversal of hyperalgesia ( ED50 ) were 7 . 54 ( 1 . 81 ) and 4 . 83 ( 1 . 54 ) in the <span class="chemical">carrageenan</span> model and 44 . 18 ( 1 . 37 ) and 9 . 14 ( 1 . 24 ) in the <span class="chemical">STZ</span> - induced neuropathy model for <span class="chemical">CNSB002</span> and <span class="chemical">morphine</span> , respectively ( mg / kg ; mean , SEM ) . 