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: Niacin extended - release / lovastatin 1 , 000 / 40 mg , dosed as initial therapy , was associated with good compliance and safety and had very low incidences of increased liver and muscle enzymes .
### Output Text:
<span class="chemical">Niacin extended - release / lovastatin</span> 1 , 000 / 40 mg , dosed as initial therapy , was associated with good compliance and safety and had very low incidences of increased liver and muscle enzymes . 