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: A patient with sinuatrial disease and implanted pacemaker was treated with amiodarone ( maximum dose 1000 mg , maintenance dose 800 mg daily ) for 10 months , for control of supraventricular tachyarrhythmias .
### Output Text:
A patient with sinuatrial disease and implanted pacemaker was treated with <span class="chemical">amiodarone</span> ( maximum dose 1000 mg , maintenance dose 800 mg daily ) for 10 months , for control of supraventricular tachyarrhythmias . 