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: CONCLUSIONS : The data show that valsartan is at least as effective as amlodipine in the treatment of mild to moderate hypertension .
### Output Text:
CONCLUSIONS : The data show that <span class="chemical">valsartan</span> is at least as effective as <span class="chemical">amlodipine</span> in the treatment of mild to moderate hypertension . 