(Reuters) — AcelRx Pharmaceuticals (NSDQ:ACRX) said the FDA wants an additional study on its Zalviso drug-device combination, which the safety watchdog already rejected once last year.

The company, with no products in the market, said today it would not resubmit Zalviso’s regulatory application this quarter as it needed more clarity from the FDA.

ACRX shares fell as much as 42% today to an 11-month low of $5.07 in early morning trading.

Zalviso’s approval is now likely only by the end of next year, against the previous estimate of early 2016, Canaccord Genuity analyst John Newman said. Newman cut his price target on the stock to $6 from $8.

“We have pushed revenues [from Zalviso] out to 2017 end," Newman wrote in a note to investors.

The FDA told the company last week that the additional clinical study was needed to evaluate risks associated with the Zalviso device, specifically issues relating to inadvertent dispensing, AcelRx said.

Zalviso, using the opioid sufentanil, is delivered using the company’s flagship NanoTab technology that enables rapid absorption when placed under the tongue. AcelRx said it plans to meet with the agency to discuss the need for an additional trial, and its potential design and objectives.

The company had said it would resubmit Zalviso’s application by the end of 2014 after the regulator rejected the drug-device last July. The error rate in a recent test with 700 Zalviso systems was below the target error rate discussed with the FDA, AcelRx said last month.

AcelRx shares had fallen 19% through Friday’s close since FDA first rejected Zalviso late July.

Shares of Medicines Co. (NSDQ:MDCO), which is developing a similar pain drug called Ionsys, fell as much as 9.9% in early trading.