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: Among various oral antiplatelets , a combination of a novel prostacyclin analogue beraprost ( BPT ) and a potent phosphodiesterase inhibitor cilostazol ( CLZ ) may result in untoward clinical effects due to possible synergistic elevation of intracellular cAMP ( cyclic adenosine 3 ' , 5 ' - monophosphate ) .
### Output Text:
Among various oral antiplatelets , a combination of a novel <span class="chemical">prostacyclin</span> analogue <span class="chemical">beraprost</span> ( <span class="chemical">BPT</span> ) and a potent phosphodiesterase inhibitor <span class="chemical">cilostazol</span> ( <span class="chemical">CLZ</span> ) may result in untoward clinical effects due to possible synergistic elevation of intracellular <span class="chemical">cAMP</span> ( <span class="chemical">cyclic adenosine 3 ' , 5 ' - monophosphate</span> ) . 