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: In a 37 - year - old woman with documented pentazocine - induced fibrous myopathy of triceps and deltoid muscles bilaterally and a three - week history of right wrist drop , electrodiagnostic examination showed a severe but partial lesion of the right radial nerve distal to the branches to the triceps , in addition to the fibrous myopathy .
### Output Text:
In a 37 - year - old woman with documented <span class="chemical">pentazocine</span> - induced fibrous myopathy of triceps and deltoid muscles bilaterally and a three - week history of right wrist drop , electrodiagnostic examination showed a severe but partial lesion of the right radial nerve distal to the branches to the triceps , in addition to the fibrous myopathy . 