Gateway Pharma Successfully Completes Phase 1 Clinical Trial for Metronidazole Delayed-Release Capsules for Clostridioides difficile Infection

ST. LOUIS, MO – October 22, 2025 – Gateway Pharmaceutical, LLC ("Gateway Pharma"), a clinical-stage, patent-holding specialty drug-delivery company focused on innovative formulations of antibiotics for difficult-to-treat bacterial infections, today announced the successful completion of its Phase 1 clinical trial for Metronidazole Delayed-Release (DR) Capsules, a Qualified Infectious Disease Product (QIDP)-designated candidate for treating Clostridioides difficile infection (CDI).

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The randomized, single-dose, active-controlled Phase 1 trial enrolled 18 healthy volunteers to compare Gateway Pharma’s Metronidazole DR Capsules (500 mg) against the marketed reference, Metronidazole Immediate-Release Tablets (Flagyl®). The study evaluated the rate and extent of drug absorption and fecal drug levels. The DR capsules, designed to bypass the small intestine and release metronidazole at the colon, demonstrated:

• Low Systemic Exposure: Blood levels showed significantly reduced oral absorption, with AUC 50% lower and Cmax 60% lower than the reference product, aligning with the goal of minimizing systemic side effects.

• High Fecal Concentrations: Fecal levels exceeded the concentration required to inhibit >95% of C. difficile clinical isolates by several-fold, surpassing levels achieved with immediate-release tablets, optimizing efficacy for CDI treatment without significantly disrupting gut microbiota.

• Excellent Safety Profile: No adverse events were reported, confirming the safety and tolerability of the DR capsule formulation.

 

Dr. Erik Dubberke, a leading CDI specialist at Barnes-Jewish Hospital and medical advisor to Gateway Pharma, stated, “For metronidazole to remain a viable treatment for CDI, a formulation ensuring reliable drug delivery to the colon is critical. This project addresses an urgent need with promising feasibility.”

 

Strategic Importance and Next Steps

Gateway Pharma’s Metronidazole DR Capsules received QIDP designation from the FDA in 2018, granting eligibility for Priority Review, Fast Track status, and an additional five years of market exclusivity, totaling eight years with Hatch-Waxman exclusivity. The company plans to present detailed Phase 1 data at national CDI-focused conferences in 2026 and engage with the FDA to discuss Phase 3 study plans.

 

About the Phase 1 Clinical Trial

The trial was a randomized, single-dose, crossover study comparing Metronidazole DR Capsules to Metronidazole Tablets, USP in 18 healthy adults under fasting conditions. Objectives included assessing comparative bioavailability (Cmax, AUC0-t, AUC0-inf), fecal drug concentrations, and safety through adverse event monitoring, clinical laboratory tests, vital signs, and electrocardiograms.

 

Preclinical Foundation

Supported by a Small Business Innovation Research (SBIR) grant from NIH/NIAID, Gateway Pharma conducted four single-dose and one multiple-dose pharmacokinetic studies in dogs at Washington University in St. Louis. These studies confirmed the DR capsules’ colon-targeting efficacy, with <50% AUC and <40% Cmax compared to the reference and >10-fold higher fecal concentrations at steady state than required to eliminate C. difficile.

 

About Clostridioides difficile Infection (CDI)

CDI, also known as Clostridium difficile infection, is a leading cause of hospital-associated gastrointestinal illness, affecting nearly 500,000 patients annually in the U.S., with a 20-30% recurrence rate. Designated an urgent threat by the CDC, CDI requires innovative treatment options due to limited available antibiotics.

 

About Gateway Pharma’s Colon-Targeting Technology

Gateway Pharma’s proprietary colon-targeting drug-delivery platform ensures precise, pediatric-friendly delivery of metronidazole and other therapeutics to the colon, reducing variability compared to existing formulations. The technology is patent-protected.

 

About Gateway Pharmaceutical, LLC

Gateway Pharma is a privately held, clinical-stage company specializing in reformulating antibiotics to address antibiotic-resistant infections through 505(b)(2) NDA pathways. The company’s mission is to develop site-specific antibiotic delivery systems to meet critical unmet needs in infectious disease treatment. For more information, visit [www.gatewaypharmallc.com].

 

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including expectations regarding QIDP benefits, clinical trial progression, regulatory approvals, and market success. Actual results may differ materially due to risks such as clinical trial outcomes, regulatory decisions, and market dynamics. Gateway Pharma undertakes no obligation to update these statements unless required by law.

 

We are actively seeking license-in partners and other collaboration opportunities.

 

Contact:

Dr. Lianli Li

Gateway Pharmaceutical, LLC

Phone: (314) 825-0689

Email: [lianlili@gatewaypharmallc.com]

 

Source: Gateway Pharmaceutical, LLC