APPLICATION OF QUALITY BY DESIGN (QbD) FOR THE FORMULATION AND EVALUATION OF SOLID LIPID NANOPARTICLES (SLNs) OF SUZETRIGINE TO ENHANCE ORAL BIOAVAILABILITY

Suzetrigine (VX-548; marketed in the United States as Journavx) is a first-in-class non-opioid analgesic that selectively inhibits the voltage-gated sodium channel NaV1.8 in peripheral sensory neurons. The U.S. Food and Drug Administration approved oral suzetrigine in January 2025 for moderate-to-severe acute pain in adults [1,2]. Although an oral tablet is available, lipid-based nanocarriers may warrant investigation only if a specific, measurable biopharmaceutical limitation is demonstrated. Solid lipid nanoparticles (SLNs) comprise a solid lipid matrix stabilized by surfactants and may influence drug dispersion, release and interaction with gastrointestinal fluids. Their performance is formulation-specific and cannot be assumed to improve absorption for every active pharmaceutical ingredient. Quality by Design (QbD), described in ICH Q8 (R2) and supported by ICH Q9 (R1) and Q10, provides a systematic framework for defining the quality target product profile (QTPP), critical quality attributes (CQAs), critical material attributes (CMAs), critical process parameters (CPPs), and a control strategy [7–9]. This review summarizes suzetrigine's pharmacological context, SLN architecture and preparation, QbD-led development, analytical characterization, stability, biorelevant testing and the evidence needed to test a potential bioavailability benefit. A proposed development pathway is presented, including preformulation screening, design of experiments (DoE), digestion studies and comparative pharmacokinetics. Key challenges include drug–lipid compatibility, possible drug expulsion during lipid crystallization, scale-up, excipient tolerability and gastrointestinal precipitation. The central conclusion is that QbD-guided suzetrigine-SLNs are a plausible research hypothesis, but their value must be established experimentally against an appropriate reference rather than inferred from the general advantages of nanocarriers.