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 have described a patient with severe rheumatoid arthritis and a history of mefenamic acid nephropathy in whom hyperkalemia and inappropriate hypoaldosteronism were caused by both indomethacin and naproxen , without major decline in renal function .
### Output Text:
We have described a patient with severe rheumatoid arthritis and a history of <span class="chemical">mefenamic acid</span> nephropathy in whom hyperkalemia and inappropriate hypoaldosteronism were caused by both <span class="chemical">indomethacin</span> and <span class="chemical">naproxen</span> , without major decline in renal function . 