Vertex Pharmaceuticals said on Tuesday its experimental non-opioid drug for treating post-surgical pain met the main goal in late stage trials but was not any more effective than some commonly used painkillers.

When compared with a placebo, the drug was more effective in reducing the intensity of pain, measured by patients' self-reported rating of their discomfort, after 48 hours in the two late-stage studies.

The treatment, however, failed to meet a secondary goal of reducing pain when compared to acetaminophen or hydrocodone. Vertex's drug, "VX-548," works by blocking pain signals at its origin before it reaches the brain.

Shares of the drugmaker fell nearly 4% to $420 premarket.

Attempts to bring new opioid alternatives to market by drugmakers such as Eli Lilly and Regeneron Pharmaceuticals have failed in past clinical trials.

Analysts have forecast more than $5 billion in annual peak sales for Vertex's drug, which would offer a less addictive option to millions of patients with acute pain, if approved.

"I don't think anybody expects that this drug will replace or mean the end of opioid pain medicines but it absolutely offers an alternative that is sorely needed," Piper Sandler analyst Christopher Raymond said ahead of data from the studies.

A third trial tested the drug for general acute pain for up to 14 days.

The late-stage studies involved patients who underwent surgery to remove bunions on the toes or abdominoplasty, commonly known as a "tummy tuck."

Nearly 645,000 people died in the United Stated from overdoses involving opioids, both prescription and illicit, from 1999 to 2021, according U.S. government data.

Having a more effective treatment than commonly-used non-steroidal anti-inflammatory drugs such as ibuprofen or acetaminophen, "without the baggage of the chance of addiction and abuse is a very big deal," Raymond says.

Vertex plans to submit marketing application to U.S. Food and Drug Administration by mid-2024.