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: Argatroban is a hepatically metabolized , direct thrombin inhibitor used for prophylaxis or treatment of thrombosis in heparin - induced thrombocytopenia ( HIT ) and for patients with or at risk of HIT undergoing percutaneous coronary intervention ( PCI ) .
### Output Text:
<span class="chemical">Argatroban</span> is a hepatically metabolized , direct thrombin inhibitor used for prophylaxis or treatment of thrombosis in <span class="chemical">heparin</span> - induced thrombocytopenia ( HIT ) and for patients with or at risk of HIT undergoing percutaneous coronary intervention ( PCI ) . 