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: DISCUSSION : Although there is increasing evidence of hepatotoxicity induced by bupropion , this is the first case of fatality that could have resulted from acute liver failure in a patient receiving bupropion while on concomitant treatment with carbimazole .
### Output Text:
DISCUSSION : Although there is increasing evidence of hepatotoxicity induced by <span class="chemical">bupropion</span> , this is the first case of fatality that could have resulted from acute liver failure in a patient receiving <span class="chemical">bupropion</span> while on concomitant treatment with <span class="chemical">carbimazole</span> . 