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: Although the oral administration of class IC drugs , including pilsicainide , is effective to terminate atrial fibrillation , careful consideration must be taken before giving these drugs to octogenarians .
### Output Text:
Although the oral administration of class IC drugs , including <span class="chemical">pilsicainide</span> , is effective to terminate atrial fibrillation , careful consideration must be taken before giving these drugs to octogenarians . 