RESUMEN
We demonstrate a systematic and rational approach to create a library of natural and modified, dialkylated amino acids based upon arginine for development of an efficient small interfering RNA (siRNA) delivery system. These amino acids, designated DiLA2 compounds, in conjunction with other components, demonstrate unique properties for assembly into monodisperse, 100-nm small liposomal particles containing siRNA. We show that DiLA2-based liposomes undergo a pH-dependent phase transition to an inverted hexagonal phase facilitating efficient siRNA release from endosomes to the cytosol. Using an arginine-based DiLA2, cationic liposomes were prepared that provide high in vivo siRNA delivery efficiency and are well-tolerated in both cell and animal models. DiLA2-based liposomes demonstrate a linear dose-response with an ED50 of 0.1 mg/kg against liver-specific target genes in BALB/c mice.
Asunto(s)
Aminoácidos/química , Liposomas/química , ARN Interferente Pequeño/genética , Animales , Femenino , Células Hep G2 , Humanos , Ratones , Ratones Endogámicos BALB CRESUMEN
Methods of rapidly and accurately assessing the chemical stability of pharmaceutical dosage forms are reviewed with respect to the major degradation mechanisms generally observed in pharmaceutical development. Methods are discussed, with the appropriate caveats, for accelerated aging of liquid and solid dosage forms, including small and large molecule active pharmaceutical ingredients. In particular, this review covers general thermal methods, as well as accelerated aging methods appropriate to oxidation, hydrolysis, reaction with reactive excipient impurities, photolysis and protein denaturation.
Asunto(s)
Preparaciones Farmacéuticas/química , Preparaciones Farmacéuticas/metabolismo , Estabilidad de Medicamentos , Humedad/prevención & control , Hidrólisis , Preparaciones Farmacéuticas/análisis , Valor Predictivo de las PruebasRESUMEN
A novel method for protection of DNA from high shear induced damage is presented. This method uses simple divalent cations and the lyophilizable alcohol, tert-butanol, to self-assemble DNA into condensed, shear-resistant forms. The DNA used in these studies was a 5600 BP plasmid DNA encoding a therapeutic gene. Various solvents and salts were used to identify optimal conditions to condense plasmid DNA. A stable formulation was identified with plasmid DNA condensed in a cosolvent solution containing 20% (v/v) tert-butanol and 1mM calcium chloride. The DNA was formulated at 100 microg/ml and condensed into rod and toroidal shapes that were approximately 50-300 nm in diameter. The rods were found to be kinetically stable for greater than 24h following their preparation. Condensation of the plasmid DNA in this manner results in nearly 100% of the plasmid DNA remaining intact after 1 min of high shear stress applied by a 50 W probe sonicator. Uncondensed control plasmid DNA is completely fragmented following 30s of identical sonication. It is believed that condensation of DNA in this manner will permit utilization of high shear-stress inducing processing techniques, such as lyophilization or spray-drying without resulting in damage to the DNA.
Asunto(s)
ADN/química , Eritropoyetina/genética , Solventes/química , Alcohol terc-Butílico/química , Animales , Cationes Bivalentes/química , Gatos , Química Farmacéutica , Estabilidad de Medicamentos , Cinética , Microscopía Electrónica , Tamaño de la Partícula , Espectrometría de Fluorescencia , Estrés MecánicoRESUMEN
This literature review presents hydrolysis of active pharmaceutical ingredients as well as the effects on dosage form stability due to hydrolysis of excipients. Mechanisms and measurement methods are discussed and recommendations for formulation stabilization are listed.
Asunto(s)
Química Farmacéutica , Estabilidad de Medicamentos , Tampones (Química) , Catálisis , Formas de Dosificación , Embalaje de Medicamentos , Excipientes/química , Concentración de Iones de Hidrógeno , Hidrólisis , Modelos Químicos , Profármacos/metabolismo , SuspensionesRESUMEN
A guide for stabilization of pharmaceuticals to oxidation is presented. Literature is presented with an attempt to be a ready source for data and recommendations for formulators. Liquid and solid dosage forms are discussed with options including formulation changes, additives, and packaging documented. In particular, selection of and methods for use of antioxidants are discussed including recommended levels.