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: The mean reduction in MSSBP / MSDBP with VAL / HCTZ 320 / 25 mg was 24 . 7 / 16 . 6 mm Hg , compared with 5 . 9 / 7 . 0 mm Hg with placebo .
### Output Text:
The mean reduction in MSSBP / MSDBP with <span class="chemical">VAL</span> / <span class="chemical">HCTZ</span> 320 / 25 mg was 24 . 7 / 16 . 6 mm Hg , compared with 5 . 9 / 7 . 0 mm Hg with placebo . 