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: Considering the fact that 5 - HTP and the benzodiazepines have been found to be beneficial in the management of clinical myoclonus , the muscimol - induced myoclonus seems to be a satisfactory animal model that may prove useful for the development of new drug treatments for this condition .
### Output Text:
Considering the fact that <span class="chemical">5 - HTP</span> and the <span class="chemical">benzodiazepines</span> have been found to be beneficial in the management of clinical myoclonus , the <span class="chemical">muscimol</span> - induced myoclonus seems to be a satisfactory animal model that may prove useful for the development of new drug treatments for this condition . 