Polyrizon Submits Pre-RFD To FDA For Its PL-16 Viral Blocker Designed To Reduce Exposure To Influenza And Cold Viruses

The PL-16 Viral Blocker has shown over 90% success in protection of cells against viruses

Raanana, Israel, Dec. 19, 2025 (GLOBE NEWSWIRE) -- Polyrizon Ltd., a pre-clinical-stage biotechnology company developing intranasal protective solutions, announced today that it has submitted a Pre-Request for Designation (Pre-RFD) to the U.S. Food and Drug Administration (FDA) for its PL-16 Viral Blocker, a non-pharmacological intranasal product designed to reduce exposure to airborne respiratory viruses, including influenza and cold viruses, by forming a temporary physical barrier on the nasal mucosa.

The Pre-RFD submission initiates a formal regulatory dialogue with the FDA regarding the appropriate regulatory pathway for PL-16 Viral Blocker, based on its formulation and physical mode of action.

This step comes at a time when seasonal respiratory infections remain a significant public health challenge. According to preliminary model-based estimates from the CDC, the 2025–2026 flu season has already resulted in at least 2.9 million symptomatic illnesses, 1.4 million medical visits, 30,000 hospitalizations, and 1,200 deaths (including about 12 pediatric deaths). These figures are early-season estimates and are expected to rise substantially as winter progresses; in a typical full flu season, illnesses can reach 9–41 million, with hundreds of thousands of hospitalizations.

About PL-16 Viral Blocker

PL-16 is a metered-dose intranasal spray containing a hydrogel formulation composed of biodegradable polymers, together with standard excipients. Upon application, PL-16 forms a thin, muco-adhesive hydrogel layer that acts as a physical barrier, mechanically reducing contact between inhaled airborne particles and the nasal epithelium.

The product is intended for local, topical use only, with no systemic exposure and no intended pharmacological, immunological, or metabolic activity.

Supporting Preclinical Evidence

The Pre-RFD submission is supported by a comprehensive package of in-vitro mechanistic studies, demonstrating that PL-16 acts via physical blocking:

• Viral blocking efficacy: In-vitro assays demonstrated that PL-16 preserved cell viability following exposure to influenza A (H1N1) and human coronavirus 229E by preventing viral access to cells.
• Blocking vs. virucidal differentiation: Dedicated studies confirmed that viruses remain infective after being recovered from the PL-16 Viral Blocker hydrogel, supporting a purely mechanical barrier mechanism.
• Dynamic barrier validation: Transwell-based experiments demonstrated effective viral blocking over several hours under dynamic conditions.

Strategic Context

The PL-16 Viral Blocker program is part of Polyrizon's broader strategy to develop non-medicated intranasal solutions designed to reduce exposure to airborne particles through physical barrier mechanisms. This strategy builds on the company's existing Capture and Contain (C&CTM) technology platform, including PL-14 Allergy Blocker, which is designed to reduce exposure to airborne allergens using a similar non-pharmacological, locally acting approach. Together, these programs reflect Polyrizon's focus on scalable, drug-free nasal technologies addressing multiple exposure-driven respiratory indications.

Next Steps

Polyrizon will engage with the FDA following receipt of Pre-RFD feedback to align on next development steps for PL-16. The company continues to advance its intranasal platform toward additional indications focused on non-medicated, barrier-based respiratory protection.