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: Using the Naranjo adverse effect reaction probability scale this event could be classified as possible ( score 5 points ) , mostly because of the close temporal sequence , previous reports on this reaction with other macrolides and the absence of any alternative explanation for hiccups .
### Output Text:
Using the Naranjo adverse effect reaction probability scale this event could be classified as possible ( score 5 points ) , mostly because of the close temporal sequence , previous reports on this reaction with other <span class="chemical">macrolides</span> and the absence of any alternative explanation for hiccups . 