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: Fewer subjects reported adverse events following treatment with desipramine alone than when receiving desipramine with cinacalcet ( 33 versus 86 % ) , the most frequent of which ( nausea and headache ) have been reported for patients treated with either desipramine or cinacalcet .
### Output Text:
Fewer subjects reported adverse events following treatment with <span class="chemical">desipramine</span> alone than when receiving <span class="chemical">desipramine</span> with <span class="chemical">cinacalcet</span> ( 33 versus 86 % ) , the most frequent of which ( nausea and headache ) have been reported for patients treated with either <span class="chemical">desipramine</span> or <span class="chemical">cinacalcet</span> . 