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: Anticholinesterases were administered in an attempt to antagonize prolonged neuromuscular blockade following the administration of succinylcholine in a patient later found to be homozygous for atypical plasma cholinesterase .
### Output Text:
Anticholinesterases were administered in an attempt to antagonize prolonged neuromuscular blockade following the administration of <span class="chemical">succinylcholine</span> in a patient later found to be homozygous for atypical plasma cholinesterase . 