Zogenix has reported positive top-line results from its pivotal phase III efficacy study (Study 801) of Zohydro (hydrocodone bitartrate) extended-release capsules. Zohydro is being evaluated for the treatment of moderate to severe chronic pain in patients requiring around-the-clock opioid therapy for an extended period of time. If approved, Zohydro could be the first extended-release hydrocodone treatment available without acetaminophen, which is associated with an increased risk of liver toxicity when used in high doses over time.

Hydrocodone pain products represent the largest prescription drug category in the United States, with over 131 million prescriptions filled in 2010. The company believes Zohydro's ability to consistently deliver hydrocodone over an extended period of time, without exposure to acetaminophen, will position the product well in this large market.

The trial successfully met the primary efficacy endpoint of the study in demonstrating Zohydro resulted in significantly improved chronic pain relief compared to placebo. The two key secondary endpoints were also met, specifically, the proportion of patients with at least 30% improvement in pain intensity and the improvement of overall satisfaction of medication. Additional study endpoints were supportive of the efficacy of Zohydro compared to placebo. The study demonstrated that Zohydro was safe and well tolerated. The most commonly reported adverse events in patients treated with Zohydro were constipation, nausea, and urinary tract infection.