Shares of AcelRx Pharmaceuticals Inc. hit an all-time high price Tuesday, after the specialty drugmaker said its NanoTab pain treatment system met its main goal in late-stage research, and the company is preparing to submit it to regulators for approval.

The Redwood City, Calif., company said patients using the system experienced a significantly greater reduction in pain following major orthopedic surgery compared with those taking a placebo or fake drug.

The NanoTab device is designed to treat severe pain following surgery by delivering a preset dose of the drug sufentanil beneath the patient’s tongue. The patient operates the device by pressing a button. AcelRx says the system is less invasive than intravenous dosing and less prone to dosing errors.

In late 2012 and early 2013, the company also said the NanoTab system met its main goals in two late-stage clinical trials involving patients who’d had major open abdominal surgery.

AcelRx, which focuses on developing pain treatments, said Tuesday that the company remains on track to submit an application for approval of the NanoTab system to regulators in the third quarter.

Company shares reached an all-time high of $7.42 Tuesday morning before retreating to $6.78. That still represented a gain of about 5 percent, or 32 cents, compared with Monday’s closing price.

AcelRx shares began trading in early 2011 after an initial public offering of the stock was priced at $5 per share. The stock closed 2012 below that price at $4.26, but the price has since climbed more than 50 percent.