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: In group II , cyclosporine was started only after the procedure at a lower dosage and was complemented by azathioprine , which was used for the first postoperative week .
### Output Text:
In group II , <span class="chemical">cyclosporine</span> was started only after the procedure at a lower dosage and was complemented by <span class="chemical">azathioprine</span> , which was used for the first postoperative week . 