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: RESULTS : Two patients ( 4 . 3 % [ 95 % CI , 0 . 6 % to 14 . 8 % ] ) receiving fenfluramine - phentermine developed valvular heart disease .
### Output Text:
RESULTS : Two patients ( 4 . 3 % [ 95 % CI , 0 . 6 % to 14 . 8 % ] ) receiving <span class="chemical">fenfluramine</span> - <span class="chemical">phentermine</span> developed valvular heart disease . 