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: On admission the patient was taking carvedilol 12 mg twice daily , warfarin 2 mg / day , folic acid 1 mg / day , levothyroxine 100 microg / day , pantoprazole 40 mg / day , paroxetine 40 mg / day , and flecainide 100 mg twice daily .
### Output Text:
On admission the patient was taking <span class="chemical">carvedilol</span> 12 mg twice daily , <span class="chemical">warfarin</span> 2 mg / day , <span class="chemical">folic acid</span> 1 mg / day , <span class="chemical">levothyroxine</span> 100 microg / day , <span class="chemical">pantoprazole</span> 40 mg / day , <span class="chemical">paroxetine</span> 40 mg / day , and <span class="chemical">flecainide</span> 100 mg twice daily . 