Vivozon Pharmaceutical isn’t waiting for prescriptions to stack before expanding its first-in-class pain drug.

Three months after securing Korea’s 38th novel drug designation, the Korean pharma firm is already rolling out a fresh phase 2 trial for Unafra (opiranserin)—this time targeting lower back pain. 

The injectable analgesic, approved domestically in December for short-term post-op pain, is now being tested for broader use in a space long dominated by opioids and NSAIDs.

Korean regulators greenlit the study on Monday, with trial sites prepping for a May kickoff. The randomized, double-blind trial will test opiranserin against placebo in adults with moderate to severe lower back pain, delivering two IV infusions—on Day 1 and Day 7—of either 180 mg of the drug or matching placebo over 30 minutes.

The primary endpoint: a two-hour summed pain intensity difference on Day 1, essentially measuring the total reduction in pain within that critical window post-infusion. Secondary goals include pain relief thresholds and rescue med usage. 

The company is targeting rollout as early as June, with commercialization locked in for the third quarter. 

Unafra is a dual GlyT2 and 5HT2A inhibitor that blocks pain transmission at both central and peripheral levels—a mechanistic departure from opioid-based painkillers and traditional anti-inflammatories. Vivozon says it's the first injectable non-opioid analgesic to win global approval.

It’s also not the only one chasing the opioid exit ramp. Just two months earlier, Vertex scored a U.S. FDA nod for Journavx (suzetrigine), a first-in-class non-opioid tablet that targets sodium channels in the peripheral nervous system. Journavx is the first drug in its category approved for acute pain in the U.S., according to the FDA, and the first real competitor for a market that’s been aching for safer alternatives. 

Vivozon, meanwhile, hasn’t yet filed an IND in the U.S., but executives say they’re ready to re-enter the ring. The company previously launched a U.S. phase 3 trial in 2020, but Covid-19 disruptions and strategic pivots shifted its focus back home, where progress—and approval—came quicker.

“Since we’re a small company, we focused company-wide last year on securing domestic approval,” a spokesperson told Korea Biomedical Review. With that milestone cleared, the company is now prioritizing a U.S. phase 3 reboot—a goal backed internally by both leadership and staff.

With over 400 patients already dosed in earlier U.S. and Korean trials and no red flags on safety, Vivozon says the U.S. program can pick up where it left off. If timelines hold, the spokesperson said the company plans to complete the trial within three years and head straight into FDA filing.

The back pain study isn’t the only expansion play on deck. A separate investigator-initiated trial at Asan Medical Center is testing opiranserin for perioperative pain, with patients receiving the drug in an extended 8-hour infusion before and after surgery, followed by another dose the next morning. Endpoints include post-op pain intensity over time and rescue medication use. 

Both studies are part of Vivozon’s broader strategy to test opiranserin in multiple real-world settings, including potential for repeated dosing—something its current short-term indication doesn’t yet cover.