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: Akathisia was controlled by the benzodiazepine lorazepam in 14 out of 16 patients , while prophylactic antiparkinsonians were ineffective .
### Output Text:
Akathisia was controlled by the <span class="chemical">benzodiazepine</span> <span class="chemical">lorazepam</span> in 14 out of 16 patients , while prophylactic antiparkinsonians were ineffective . 