(Reuters) - AcelRx Pharmaceuticals Inc said a mid-stage trial of its experimental pain drug showed that a higher dose of the therapy met the main goal of reducing acute pain in patients, but the lower dose failed to meet the goal.
Shares of the company fell 4 percent to $5.92 on Wednesday morning on the Nasdaq. However, analysts said they viewed the trial data as positive.
"The whole point of a dose-finding trial is to find the lowest efficacious dose, and they have done that at the higher dose of 30 mcg. So, I don't read a lot into the lower dose," MLV & Co analyst Ed Arce said.
Results from the trial showed that patients receiving a 30 mcg dose of the drug, administered not more than once per hour, had significantly greater pain reduction - as measured by a standard score - than those given a placebo.
Patients receiving 20 mcg of the drug, called ARX-04, did not achieve a score that differentiated it from the placebo.
ARX-04 consists of sufentanil, an opioid, in AcelRx's NanoTab technology that enables rapid absorption when the NanoTab is placed under the tongue.
There were two serious adverse events of post-surgical infection, both of which were determined by the study investigator to be unrelated to the drug, the company said.
Two patients dropped out of the study due to adverse events, with one patient's discontinuation considered unrelated to the drug, and the other considered "probably related" to the drug.
The trial tested 101 patients following a toe surgery called bunionectomy.
The specialty pharmaceutical company focuses on developing therapies for the treatment of acute and breakthrough pain.
Its product, sufentanil NanoTab, is being tested in four trials for the treatment of post-operative pain, breakthrough pain in cancer patients, pain relief for patients undergoing procedures in a physician's office and acute pain.
The lead program ARX-01, for post-operative pain, is currently in late-stage development. The remaining, ARX-02, ARX-03 - a combination of sufentanil and triazolam - and ARX-04, are in mid-stage trials.
Reporting by Esha Dey in Bangalore; Editing by Roshni Menon