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: Half log incremental doses of intravenous methoxamine or placebo ( saline ) were administered to a group of women with genuine stress incontinence while measuring maximum urethral pressure ( MUP ) , blood pressure , heart rate , and symptomatic side effects .
### Output Text:
Half log incremental doses of intravenous <span class="chemical">methoxamine</span> or placebo ( saline ) were administered to a group of women with genuine stress incontinence while measuring maximum urethral pressure ( MUP ) , blood pressure , heart rate , and symptomatic side effects . 