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: Additionally , in terms of management of EMB - induced optic neuropathy , it is important to properly manage ethambutol dosing in patients with renal impairment and to achieve proper transition to a maintenance dose once an appropriate loading dose has been reached .
### Output Text:
Additionally , in terms of management of <span class="chemical">EMB</span> - induced optic neuropathy , it is important to properly manage <span class="chemical">ethambutol</span> dosing in patients with renal impairment and to achieve proper transition to a maintenance dose once an appropriate loading dose has been reached . 