AcelRx Pharma's Stock Tumbles After FDA Request Delays Zalviso NDA

Shares of AcelRx Pharmaceuticals plummeted 39% in active, premarket trade Monday, after the drug company said the U.S. Food and Drug Administration surprisingly requested and additional study to evaluate dispensing failures in previous studies of its pain treatment. AcelRx said the FDA previously indicated that the bench tests and two human factors studies AcelRx performed to assess inadvertent dispensing and risk of dispensing failures were acceptable. As a result of the updated FDA requirements, AcelRx said it will not be resubmitting the new drug application for its Zalviso device this quarter. AcelRx said it plans to meet with the FDA to discuss the need for an additional clinical study. The stock's selloff puts it on track to open at a five-month low. Through Friday, it had surged 32% in the past three months, while the S&P 500 has gained 0.6%.