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: We prospectively evaluated the incidence of venous complications after intravenous injection of diazepam or midazolam in 122 consecutive patients undergoing colonoscopy and esophagogastroduodenoscopy .
### Output Text:
We prospectively evaluated the incidence of venous complications after intravenous injection of <span class="chemical">diazepam</span> or <span class="chemical">midazolam</span> in 122 consecutive patients undergoing colonoscopy and esophagogastroduodenoscopy . 