20 cents is getting killed? Look at average daily volatility. 20 cents is nothing. The candlestick yesterday (long upper tail, black body) suggests it will bounce around this level for some time, unless there is news. Don't worry about it. The shorts want you to get cold feet.
I did the same recently. I have 4K shares. I think there is a reasonable chance that this gets bought out by DaVita for 1.3-1.5 billion even before FDA approval (which is imminent). Read all of the Propthink articles on seekingalpha (propthink is a good research outfit, judging by the quality of their articles). Something like Zerenex gives DaVita a huge advantage over other dialysis companies, most especially Fresenius, the world's largest. Tjhen again, it could be more interesting to Fresenius. At a $678 million market cap, KERX is an easy double, if not a triple IMHO. Zenerex is a blockbuster drug.