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: An increase of creatine phosphokinase to > 5 times the upper limit of normal occurred in 0 . 24 % of patients , and no cases of drug - induced myopathy were observed .
### Output Text:
An increase of <span class="chemical">creatine</span> phosphokinase to > 5 times the upper limit of normal occurred in 0 . 24 % of patients , and no cases of drug - induced myopathy were observed . 