Questcor Plummets After Aetna Limits Coverage of Company's Drug

Aetna

said on Wednesday that it would limit coverage of a multiple sclerosis and infant seizure drug from Questcor Pharmaceuticals

. The news caused shares of Questcor to plunge as much as 56 percent in morning trading, the largest one-day drop for the stock since 1993. At last check, QCOR had retraced some of its losses and was down 31 percent to just below $34.00. The drug, called Athar, helped the company to nearly double sales in the second-quarter. According to Aetna's website, studies suggest that the drug is only "medically necessary" for West Syndrome, which is a condition that causes spasms in infants. The statement goes on to say that for multiple sclerosis, the gel hasn't been shown to be more effective than current treatments or at all. Aetna only reimburses for drugs that is deems medically necessary according to a spokeswoman. Prior to Wednesday's plunge, shares of Questcor had risen 22 percent in 2012.