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: All 36 patients receiving lamivudine had a decrease in hepatitis B virus ( HBV ) DNA values of > 90 % ( P < . 001 compared with placebo ) .
### Output Text:
All 36 patients receiving <span class="chemical">lamivudine</span> had a decrease in hepatitis B virus ( HBV ) DNA values of > 90 % ( P < . 001 compared with placebo ) . 