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 patients requiring the concurrent use of statins and CYP3A4 inhibitors , pravastatin , fluvastatin , and rosuvastatin carry the lowest risk of drug interactions ; atorvastatin carries moderate risk , whereas simvastatin and lovastatin have the highest risk and should be avoided in patients taking concomitant CYP3A4 inhibitors .
### Output Text:
In patients requiring the concurrent use of <span class="chemical">statins</span> and CYP3A4 inhibitors , <span class="chemical">pravastatin</span> , <span class="chemical">fluvastatin</span> , and <span class="chemical">rosuvastatin</span> carry the lowest risk of drug interactions ; <span class="chemical">atorvastatin</span> carries moderate risk , whereas <span class="chemical">simvastatin</span> and <span class="chemical">lovastatin</span> have the highest risk and should be avoided in patients taking concomitant CYP3A4 inhibitors . 