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: Times to ambulate and to void were similar after lidocaine and prilocaine ( 150 vs . 165 min and 238 vs . 253 min , respectively ) but prolonged after bupivacaine ( 200 and 299 min , respectively ; P < 0 . 05 ) .
### Output Text:
Times to ambulate and to void were similar after <span class="chemical">lidocaine</span> and <span class="chemical">prilocaine</span> ( 150 vs . 165 min and 238 vs . 253 min , respectively ) but prolonged after <span class="chemical">bupivacaine</span> ( 200 and 299 min , respectively ; P < 0 . 05 ) . 