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: INTRODUCTION : The possible anxiogenic effects of fluoroquinolones , namely ciprofloxacin and norfloxacin , were investigated in adult Charles Foster albino rats of either sex , weighing 150 - 200 g .
### Output Text:
INTRODUCTION : The possible anxiogenic effects of <span class="chemical">fluoroquinolones</span> , namely <span class="chemical">ciprofloxacin</span> and <span class="chemical">norfloxacin</span> , were investigated in adult Charles Foster albino rats of either sex , weighing 150 - 200 g . 