AcelRx Pharmaceuticals, Inc. has announced additional data from the Phase II dose-finding study of ARX-04, an investigational single-dose sublingual sufentanil NanoTab for moderate-to-severe acute pain. Patients treated with the 30 mcg dose of sufentanil showed a rapid onset of action with a statistically significant beneficial difference in pain relief (p<0.001) and pain intensity (p<0.01) seen at 30 minutes after dosing compared to placebo. Dosing averaged every 2.4 hours over the duration of the 12-hour study.

In addition, patient global assessment of the 30 mcg dose at 12 hours was superior to placebo (p=0.002) with 43.6% vs. 5.0% of the patients responding good or excellent for overall pain control. The 20 mcg dose was not significant for either endpoint.

This study was funded by a grant from the US Army Medical Research and Materiel Command. The intent-to-treat (ITT) population in this study averaged 42.5 years of age and was evenly balanced for males and females (51%:49%). 91% of patients entering the study completed the full 12-hour study period.

SPID-12 (Summed Pain Intensity Difference to baseline during the 12-hour study period) scores, the primary endpoint, were +6.53 for 30 mcg sufentanil-treated patients and -7.12 for placebo-treated patients, the difference between the two groups being highly statistically significant (p=0.003). The 20 mcg sufentanil-treated patients did not achieve SPID-12 scores that differentiated from placebo. For the time-weighted sum of pain relief scores over the 12-hour study period, or TOTPAR12, there was a statistically significant difference in favor of the 30 mcg group over placebo (9.73 vs.

4.37 p = 0.002). Two serious adverse events (SAEs), both in the 20 mcg-dose group, occurred one week after the study (surgical infections) and were deemed unrelated to study drug. All but two adverse events reported in the study were mild-to-moderate in nature with 58 patients (58%) reporting a total of 135 adverse events.

The most frequently reported adverse events for all patients were nausea (30%), vomiting (17%), dizziness (14%) and somnolence (11%). Two patients discontinued treatment, one unrelated to study drug (anxiety/chest pain) and the other probably related to study drug (somnolence/respiratory depression), however both patients recovered without medical intervention.