RESUMEN
PURPOSE: To understand hydrolysis and alcoholysis of polyvinylpyrrolidone-co-vinylacetate (PVPVA) during formulation and storage, elucidate the reaction mechanism, establish an intrinsic kinetic model, and apply this model coupled with GastroPlus™ modeling to predict the amount of PVPVA degradation in vivo. METHODS: The experimental approach includes the detection of the polymer reaction by solution nuclear magnetic resonance (NMR) and the measurement of reaction product concentration via gas chromatography (GC). The theoretical approach includes the establishment of the intrinsic kinetic model and the application of GastroPlus™ to predict the degree of PVPVA degradation. RESULTS: The kinetic model established is a first order reaction between PVPVA and 2-propanol (IPA) or water under an acidic condition. The application of this kinetic model shows that between 1.7 and 6.8 mg of degradant is formed in the GI tract for a 850 mg dose of PVPVA. CONCLUSIONS: The results from this application provide valuable input for process development and the risk analysis of the degradation of PVPVA.
Asunto(s)
Excipientes/química , Modelos Biológicos , Modelos Químicos , Povidona/análogos & derivados , 2-Propanol/química , Simulación por Computador , Composición de Medicamentos , Almacenaje de Medicamentos , Excipientes/farmacocinética , Estudios de Factibilidad , Humanos , Concentración de Iones de Hidrógeno , Hidrólisis , Mucosa Intestinal/metabolismo , Espectroscopía de Resonancia Magnética , Povidona/química , Povidona/farmacocinética , Programas Informáticos , Agua/químicaRESUMEN
Subcutaneous injection of concentrated protein and peptide solutions, in the range of 100-400 mg/mL, is often not possible with a 25- to 27-gauge needle, as the viscosity can be well above 50 cP. Apparent viscosities below this limit are reported for suspensions of milled lysozyme microparticles up to nearly 400 mg/mL in benzyl benzoate or benzyl benzoate mixtures with safflower oils through a syringe with a 25- to 27-gauge needle at room temperature. These apparent viscosities were confirmed using a cone-and-plate rheometer. The intrinsic viscosity regressed from the Kreiger-Dougherty model was only slightly above the Einstein value of 2.5, indicating the increase in viscosity relative to that of the solvent was caused primarily by the excluded volume. Thus, the increases in viscosity from electrical double layer interactions (electroviscous effects), solvation of the particles, or deviations of the particle shape from a spherical geometry were minimal, and much smaller than typically observed for proteins dissolved in aqueous solutions. The small electroviscous effects are expected given the negligible zeta potential and thin double layers in the low dielectric constant organic solvent. The suspensions were resuspendable after a year, with essentially constant particle size after two months as measured by static light scattering. The lower apparent viscosities for highly concentrated protein suspensions relative to protein solutions, coupled with these favorable characteristics upon resuspension, may offer novel opportunities for subcutaneous injection of therapeutic proteins.
Asunto(s)
Muramidasa/química , Nanopartículas/química , Suspensiones/química , Benzoatos/química , Reología , Aceite de Cártamo/química , Temperatura , ViscosidadRESUMEN
PURPOSE: Highly stable, submicron lactate dehydrogenase (LDH) and lysozyme particles may be produced by thin film freezing (TFF) of aqueous solutions followed by lyophilization. METHODS: The LDH activity was determined by measuring the decrease in absorbance of NADH over time for the reaction of pyruvate to lactate. For lysozyme the particle morphology was determined by scanning electron microscopy (SEM) and compared with the specific surface area (BET) and the particle size, as measured by laser light scattering, RESULTS: Protein particles with an average diameter of 300 nm and 100% enzyme activity upon reconstitution (for LDH) were formed by TFF. Droplets of protein solutions, 3.6 mm in diameter, spread upon impact with 223 and 133 K metal surfaces to form cylindrical disks with thicknesses of 200-300 microm. Calculated cooling rates of the disks of 10(2) K/s were confirmed experimentally with infrared measurements. CONCLUSIONS: The cooling rates of 10(2) K/s, intermediate to those in lyophilization (1 K/min) and spray freeze-drying (SFD) (10(6) K/s), were sufficiently fast to produce sub-micron protein particles with surface areas of 31-73 m2/g, an order of magnitude higher than in lyophilization. In addition, the low surface area/volume ratio (32-45 cm(-1)) of the gas-liquid interface led to minimal protein adsorption and denaturation relative to SFD.