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: Bradycardia occurred in a 45 - year - old male patient who was Viracept in combination with other anti - HIV drugs .
### Output Text:
Bradycardia occurred in a 45 - year - old male patient who was <span class="chemical">Viracept</span> in combination with other anti - HIV drugs . 