Scilex aims to dethrone Endo in billion-dollar pain subsegment using novel transdermal patch

Malvern, PA's Scilex Pharmaceuticals is seeking to deploy its transdermal drug delivering patch to break into the post-herpetic neuralgia market, which is led by an Endo drug that had peak sales of $1.4 billion.

Scilex CEO Anthony Mack

Scilex's first-line ZTlido patch will be approved (or rejected) to treat post-herpetic neuralgia (also known as post-shingles pain) by the FDA's PDUFA date of May 10, CEO and co-founder Anthony Mack told FierceDrugDelivery in an interview. In 2009, he founded transdermal technology manufacturing company ProSolus Pharmaceuticals, which was recently acquired by Mission Pharmacal.

Scilex hopes to dethrone Endo's ($ENDP) generic Lidoderm lidocaine patch by providing improved drug delivery in the form of improved adhesion. During clinical development, the patch demonstrated a statistically significant improvement in adhesion compared to Lidoderm, the company says. Both patches, current and investigational, are designed to be worn continuously over a 12-hour period.

"If the patch doesn't stay in contact with the skin for the full recommended dose, it will be a failed therapeutic," Mack said. He described the ZTlido patch as a single-layer topical delivery system, which uses what's known as hot-melt, pressure-sensitive adhesives.

The patch delivers 36 milligrams of lidocaine compared to 700 milligrams in the case of Lidoderm, reducing the potential for side effects, and alleviating FDA concerns about drug disposal. Because the ZTlido's formulation does not require water, the manufacturing cost is about half of Lidoderm's, Mack said.

He believes the drug delivery enhancement will appeal to payers because the ZTlido will reduce the usage of extra patches, thereby saving them expenditures. Endo recommends wearing up to three Lidoderm patches at a time.

And then there's the classical argument of downstream saving from improved efficacy and/or compliance: "It's not a matter of if, it's a matter of when patients will go to a concomitant medication because it's so difficult to treat," Mack said, adding that post-herpetic neuralgia can last for weeks to an entire lifespan.

In addition to Lidoderm, there are several injectable versions of lidocaine that are used at hospitals. But ZTlido will compete with Lidoderm in the self-administered segment of the market.

Mack wouldn't disclose the planned pricing (assuming FDA approval), but said the company will price ZTlido so that primary care physicians and pain specialists won't have to obtain prior authorization (or permission) from payers to prescribe the medication.

About 100 representatives from sales force provider inVentiv Health will promote ZTlido beginning in the second half of 2016, assuming approval. Mack said that Endo does not promote Lidoderm because it is a generic medication.

Scilex filed for approval via the FDA's 505(b)(2) pathway, for drugs that are similar to a previously approved product and require additional studies beyond those proving bioequivalence and bioavailability, but not full-blown safety and efficacy data.