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 incidence and severity of succinylcholine - associated myalgia was determined in 64 patients pretreated with saline or dexamethasone before succinylcholine ( n = 32 for each ) .
### Output Text:
The incidence and severity of <span class="chemical">succinylcholine</span> - associated myalgia was determined in 64 patients pretreated with saline or <span class="chemical">dexamethasone</span> before <span class="chemical">succinylcholine</span> ( n = 32 for each ) . 