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: RESULTS : Patients receiving concomitant AmB and spironolactone had significantly higher plasma potassium levels than those receiving AmB alone ( P = 0 . 0027 ) .
### Output Text:
RESULTS : Patients receiving concomitant <span class="chemical">AmB</span> and <span class="chemical">spironolactone</span> had significantly higher plasma <span class="chemical">potassium</span> levels than those receiving <span class="chemical">AmB</span> alone ( P = 0 . 0027 ) . 