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: In a randomized study , labetalol - induced hypotension and nitroprusside - induced hypotension were compared in 20 patients ( 10 in each group ) scheduled for major orthopedic procedures .
### Output Text:
In a randomized study , <span class="chemical">labetalol</span> - induced hypotension and <span class="chemical">nitroprusside</span> - induced hypotension were compared in 20 patients ( 10 in each group ) scheduled for major orthopedic procedures . 