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: CASE SUMMARIES : Two patients developed prolonged cholestatic hepatitis after receiving ticlopidine following percutaneous coronary angioplasty , with complete remission during the follow - up period .
### Output Text:
CASE SUMMARIES : Two patients developed prolonged cholestatic hepatitis after receiving <span class="chemical">ticlopidine</span> following percutaneous coronary angioplasty , with complete remission during the follow - up period . 