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: Spironolactone : is it a novel drug for the prevention of amphotericin B - related hypokalemia in cancer patients ?
### Output Text:
<span class="chemical">Spironolactone</span> : is it a novel drug for the prevention of <span class="chemical">amphotericin B</span> - related hypokalemia in cancer patients ? 