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: Myopathy , associated in some cases with myoglobinuria , and in 2 cases with transient renal failure , has been rarely reported with lovastatin , especially in patients concomitantly treated with cyclosporin , gemfibrozil or niacin .
### Output Text:
Myopathy , associated in some cases with myoglobinuria , and in 2 cases with transient renal failure , has been rarely reported with <span class="chemical">lovastatin</span> , especially in patients concomitantly treated with <span class="chemical">cyclosporin</span> , <span class="chemical">gemfibrozil</span> or <span class="chemical">niacin</span> . 