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: Due to an accidental malfunctioning of the infusion pump , the patient was inadvertently administered a toxic dosage of the drug which caused renal insufficiency .
### Output Text:
Due to an accidental malfunctioning of the infusion pump , the patient was inadvertently administered a toxic dosage of the drug which caused renal insufficiency . 