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 standard of care for management of RIHA is reduction or discontinuation of the ribavirin dosage .
### Output Text:
The standard of care for management of RIHA is reduction or discontinuation of the <span class="chemical">ribavirin</span> dosage . 