RESUMEN
To elaborate the decisive role of surfactants in promotion of aceclofenac' skin absorption, potentially avoiding irritation, we developed non-ionic microemulsions varying natural or synthetic surfactants: sucrose esters (laurate or myristate) vs. polysorbate 80. A comprehensive physicochemical characterization indicated no significant influence of the solubilized nonsteroidal anti-inflammatory drug on the bicontinuous structure of blank formulations. To evaluate skin tolerability of isopropyl alcohol, a sucrose ester-based microemulsion containing transcutol P as a cosurfactant was also developed. The measured skin parameters strongly depended on the (co)surfactant type, showing higher compatibility of the microemulsions containing sucrose ester and isopropyl alcohol. In vitro release results, in vivo tape stripping and pharmacokinetics in rats confirmed superiority of the sucrose ester- over polysorbate-based microemulsions (total amounts of aceclofenac penetrated 60.81±5.97 and 60.86±3.67 vs. 27.00±5.09µg/cm(2), and its maximum plasma concentrations 275.57±109.49 and 281.31±76.76 vs. 150.23±69.74ng/ml for sucrose laurate- and myristate- vs. polysorbate 80-based microemulsions, respectively). Hence, sugar-based excipients increased delivery of aceclofenac through stratum corneum by increasing its fluidity, showing overall more satisfying safety profiles. In conclusion, sucrose ester-based microemulsions proved to be promising carriers for dermal/transdermal aceclofenac delivery.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacocinética , Diclofenaco/análogos & derivados , Absorción Cutánea , Tensoactivos/farmacología , Adulto , Animales , Materiales Biocompatibles , Rastreo Diferencial de Calorimetría , Diclofenaco/química , Diclofenaco/farmacocinética , Emulsiones , Femenino , Humanos , Irritantes/farmacología , Masculino , Ratas , Ratas Wistar , Solubilidad , Sacarosa/químicaRESUMEN
This paper describes design and evaluation of parenteral lecithin-based nanoemulsions intended for brain delivery of risperidone, a poorly water-soluble psychopharmacological drug. The nanoemulsions were prepared through cold/hot high pressure homogenization and characterized regarding droplet size, polydispersity, surface charge, morphology, drug-vehicle interactions, and physical stability. To estimate the simultaneous influence of nanoemulsion formulation and preparation parameters--co-emulsifier type, aqueous phase type, homogenization temperature--on the critical quality attributes of developed nanoemulsions, a general factorial experimental design was applied. From the established design space and stability data, promising risperidone-loaded nanoemulsions (mean size about 160 nm, size distribution <0.15, zeta potential around -50 mV), containing sodium oleate in the aqueous phase and polysorbate 80, poloxamer 188 or Solutol(®) HS15 as co-emulsifier, were produced by hot homogenization and their ability to improve risperidone delivery to the brain was assessed in rats. Pharmacokinetic study demonstrated erratic brain profiles of risperidone following intraperitoneal administration in selected nanoemulsions, most probably due to their different droplet surface properties (different composition of the stabilizing layer). Namely, polysorbate 80-costabilized nanoemulsion showed increased (1.4-7.4-fold higher) risperidone brain availability compared to other nanoemulsions and drug solution, suggesting this nanoemulsion as a promising carrier worth exploring further for brain targeting.
Asunto(s)
Encéfalo/metabolismo , Emulsiones/química , Nanopartículas/química , Risperidona/administración & dosificación , Risperidona/farmacocinética , Animales , Química Farmacéutica , Sistemas de Liberación de Medicamentos , Estabilidad de Medicamentos , Emulsionantes , Lecitinas/química , Masculino , Tamaño de la Partícula , Poloxámero/química , Polietilenglicoles/química , Polisorbatos/química , Ratas , Ratas Wistar , Solubilidad , Ácidos Esteáricos/química , Tecnología FarmacéuticaRESUMEN
With the aid of experimental design, we developed and characterized nanoemulsions for parenteral drug delivery. Formulations containing a mixture of medium-chain triglycerides and soybean oil as oil phase, lecithin (soybean/egg) and polysorbate 80 as emulsifiers, and 0.1 M phosphate buffer solution (pH 8) as aqueous phase were prepared by cold high-pressure homogenization. To study the effects of the oil content, lecithin type, and the presence of diazepam as a model drug and their interactions on physicochemical characteristics of nanoemulsions, a three factor two-level full factorial design was applied. The nanoemulsions were evaluated concerning droplet size and size distribution, surface charge, viscosity, morphology, drug-excipient interactions, and physical stability. The characterization revealed the small spherical droplets in the range 195 -220 nm with polydispersity index below 0.15 and zeta potential between -30 and - 60 mV. Interactions among the investigated factors, rather than factors alone, were shown to more profoundly affect nanoemulsion characteristics. In vivo pharmacokinetic study of selected diazepam nanoemulsions with different oil content (20%, 30%, and 40%, w/w) demonstrated fast and intense initial distribution into rat brain of diazepam from nanoemulsions with 20% and 30% (w/w) oil content, suggesting their applicability in urgent situations.