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: PATIENTS AND METHODS : A total of 4086 patients ( mean age 60 . 8 years ) diagnosed with RA were enrolled and received etoricoxib 90 mg daily ( n = 2032 ) or diclofenac 75 mg twice daily ( n = 2054 ) .
### Output Text:
PATIENTS AND METHODS : A total of 4086 patients ( mean age 60 . 8 years ) diagnosed with RA were enrolled and received <span class="chemical">etoricoxib</span> 90 mg daily ( n = 2032 ) or <span class="chemical">diclofenac</span> 75 mg twice daily ( n = 2054 ) . 