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: We present a patient with pseudoacromegaly that resulted from the long - term use of minoxidil at an unusually high dose .
### Output Text:
We present a patient with pseudoacromegaly that resulted from the long - term use of <span class="chemical">minoxidil</span> at an unusually high dose . 