Platform technology and alternates for cross-linking issues in soft gelatin capsules: A modified shell composition...

Soft gelatin capsules (softgels) are widely used oral dosage forms for BCS Class IV drug candidates, offering enhanced solubilization capacity for poorly soluble, poorly permeable active pharmaceutical ingredients. However, gelatin shells are susceptible to progressive cross-linking during storage, particularly when reactive fill components - including oxidized lipids, aldehydes, or free amino acids - are present. Cross-linking induces shell in solubilization that delays or prevents disintegration, with potential consequences for bioavailability. This study evaluated a modified gelatin shell platform incorporating hydrophilic shell-modifying excipients - hydroxypropyl methylcellulose (HPMC), Povidone K30, and hydroxypropyl cellulose (HPC/Klucel LF) as water-soluble polymers, and microcrystalline cellulose (MCC PH105) as a water-insoluble but highly hydrophilic swellable particulate - as formulation-level cross-linking mitigation strategies. Six modified formulations (FT1-FT6) and six conventional gelatin-glycerin controls (FC1-FC6) were encapsulated with reactive fill systems, including aged omega-3 oils (elevated peroxide value), L-Arginine, and Glucosamine HCl/Chondroitin Sulfate combinations. Disintegration performance was assessed per USP <701> under ICH Q1A(R2)-compliant stability conditions at 25 degrees C/60% RH, 30 degrees C/65% RH, and 40 degrees C/75% RH over six months. All modified formulations maintained pharmacopeial compliance (30 min or less) throughout the full study period under all storage conditions. The Povidone K30-based system (FT4) demonstrated superior resistance to L-Arginine-induced cross-linking, with disintegration times below 12 minutes after six months of accelerated storage. In contrast, conventional formulations frequently exceeded the pharmacopeial limit, with failures recorded as early as the three-month accelerated time point. Strategic incorporation of water-soluble excipients within the gelatin matrix represents a practical, scalable, and manufacturing-compatible approach to cross-linking mitigation in softgels containing chemically reactive fills.