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: Massive proteinuria and acute renal failure after oral bisphosphonate ( alendronate ) administration in a patient with focal segmental glomerulosclerosis .
### Output Text:
Massive proteinuria and acute renal failure after oral <span class="chemical">bisphosphonate</span> ( <span class="chemical">alendronate</span> ) administration in a patient with focal segmental glomerulosclerosis . 