Influence of surfactant structure in the encapsulation and stability of amphotericin B in niosomes

Bilayer vesicles, such as liposomes and niosomes, are widely known as efficient delivery systems for drugs. Spherical vesicles consisting of amphipatic non-ionic surfactants named niosomes are arranged in one or more concentric bilayers. They can entrap both water and oil soluble substances in the inner aqueous phase and in the vesicular membrane, respectively. Niosomes are studied as an alternative to liposomes because they overcome the disadvantages associated with liposomes. The present study aimed to evaluate noisome formation from different surfactants and the encapsulation of amphotericin B as an amphiphilic model drug. Niosomes of Span 60®, Span 80®, Glyceryl monooleate, Dehydol® LS 2 HN (lauric alcohol 2EO) or Brij ®72 (Polyoxyethylene (2) Stearyl Ether) were prepared with the inclusion of cholesterol (ratio 1:1) by a modified ether injection technique. Two concentrations, 20 and 30 mM were studied. Span 60® and Span 80® 30mM formulations were the most stable and also the ones with higher entrapment capacity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Inhibition of fluconazole in vitro antifungal activity in formulations containing propylene glycol

Inhibition action of propylene glycol (PG) on the antifungal activity of fluconazole has been investigated. PG was used as cosolvent and penetration enhancer in different solutions and topical dosage forms. The interaction was analyzed by comparing with Transcutol P® (TCL), another cosolvent and penetration enhancer. Solubility of the drug was evaluated in aqueous solutions containing PG or TCL and the crystallized drug was studied by both DSC and FTIR. Solutions of the drug in the solvents were studied by FTIR and UV spectroscopy. Antifungal activity was determined for solutions with several concentrations of PG/TCL and in dosage forms with PG 10 %. Candida albicans was used as a model fungus and a procedure with standardized inoculum concentration was used. Results showed lower antifungal activity of fluconazole solutions and topical dosage forms when propylene glycol is included. Although crystallization is faster in PG solutions, solubility proved not to be the cause, but changes in FTIR spectra suggested that different hydrogen bond formation could explain the decrease in activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Amphiphilic block copolymers and their pharmaceutical applications

Los copolímeros en bloques están formados por macromoléculas constituidas por bloques poliméricos dispuestos en una secuencia lineal. Entre los copolímeros en bloques con aplicaciones farmacéuticas se destacan los anfifílicos, que poseen bloques lipofílicos unidos a bloques hidrofílicos. Los copolímeros en bloques anfifílicos poseen propiedades tensoactivas y forman distintas clases de asociaciones, tales como micelas y estructuras líquido cristalinas, que pueden actuar como excelentes vehículos de principios activos. En este trabajo se presenta una actualización relativa a la composición, formación de agregados y aplicaciones farmacéuticas de este tipo de sustancias.Block copolymers are formed by macromolecules which are composed of blocks in linear sequence. From the pharmaceutical point of view, main block copolymers are amphiphilic block copolymers having united hydrophilic blocks to lipophilic blocks. Amphiphilic block copolymer have surfactant properties and form different kinds of associations, such as micelles and liquid crystalline structures, that can act like excellent vehicles of active principles. In this work is presented a review of the composition, aggregate formation and pharmaceutical applications of this type of substances.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Intranasal administration of antiretroviral-loaded micelles for anatomical targeting to the brain in HIV

We investigated the intranasal administration of poly(ethylene oxide)–poly(propylene oxide) polymeric micelles loaded with high payloads of the first-line antiretroviral drug efavirenz for targeting to the CNS. The effect of micellar size and composition and drug payload was assessed, employing simple micelles made of a highly hydrophilic copolymer, poloxamer F127, loaded with 20 mg/ml drug and mixed micelles containing 75% of a medium hydrophobic poloxamine, T904, and 25% F127 loaded with 20 and 30 mg/ml drug, respectively. F127 confers high physical stability, while T904 substantially improves the encapsulation capacity of the micelles. The bioavailability of the drug in the CNS was increased fourfold and the relative exposure index (ratio between the area-under-the-curve in the CNS and plasma) was increased fivefold with respect to the same system administered intravenously. These findings demonstrate the potential of this scalable and cost-viable strategy to attack the HIV sanctuary in the CNS.Fil: Chiappetta, Diego Andrés. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina;Fil: Hocht, Christian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; Argentina;Fil: Opezzo, Javier A. W.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; Argentina;Fil: Sosnik, Alejandro Dario. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina

Release of caffeine from two liquid-crystalline systems

En este trabajo se evaluaron dos sistemas líquido-cristalinos liotrópicos para la liberación sostenida de cafeína en ensayos in vitro: uno formado por una mezcla de Poloxamer 407 y agua, que presenta la fase cúbica micelar normal, y otro constituido por alcohol oleílico con 10 moles de óxido de etileno y agua, que posee una estructura hexagonal normal. En el ensayo de permeación se emplearon membranas de poli(difluoruro de viniledeno) impregnadas con una mezcla de lípidos que simulan la composición de la matriz lipídica del estrato córneo. Los ensayos realizados con estas membranas muestran que ambos sistemas líquido-cristalinos serían adecuados para la liberación sostenida de principios activos.Two lyotropic liquid-crystalline systems for in vitro caffein liberation were evaluated: one formed by a mixture of 407 Poloxamer and water, that displays micelar normal cubical phase, and other constituted by oleyl alcohol with 10 mol of oxide of ethylene and water, that has a normal hexagonal structure. In the penetration test membranes of poli(viniledene difluorure) impregnated with a lipid mixture that simulates the composition of the lipidic matrix of the stratum corneum were used. The tests made with these membranes show that both liquid-crystalline systems would be suitable for the liberation of active principles.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Vehiculization of proteins in biodegradable microspheres

Se obtuvieron microesferas de poli(D,L-láctico-co-glicólico) conteniendo ovoalbúmina por medio de una emulsión múltiple agua en aceite en agua empleando una técnica de evaporación de solvente. Se realizó un experimento con un diseño factorial 23 para estudiar el efecto de tres variables independientes (cantidad de principio activo, cantidad de polímero y concentración de alcohol polivinílico) sobre las variables dependientes (eficacia de encapsulación y tamaño de partícula). Las tres variables independientes influyeron significativamente sobre la eficacia de encapsulación de la ovoalbúmina. En el caso del tamaño de partícula, también las tres variables ejercieron una influencia significativa. Los estudios de liberación in vitro han mostrado que después de un efecto inicial inmediato de liberación, se ha obtenido una liberación de ovoalbúmina en forma sostenida durante 28 días.Microspheres of poly(D,L-lactide-coglicolide) containing ovalbumin were prepared by the solvent evaporation method using a multiple water in oil in water emulsion 23 factorial design was used to determine the effect of three independent variables (amount of drug, amount of polymer and concentration of polyvinyl alcohol) over the dependent variables (efficacy of entrapment and particle size). The three independent variables influenced significantly over the efficacy of entrapment. In the particle size case, also the three variables influenced significantly. The in vitro release studies have shown that after an immediate initial effect of release, has obtained a sustained release among 28 days.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Micro/Nanostructured Hyaluronic Acid Matrices with Tuned Swelling and Drug Release Properties

Hyaluronic acid (HA) hydrogels were structured in the form of porous monoliths by means of the ice-segregation-induced self-assembly (ISISA) method coupled with freeze–drying. Physical and chemical parameters were explored in order to fine-tune the microstructure and the incidence on both swelling and dissolution behavior in aqueous media. Gentamicin-loaded HA matrices with tuned drug release properties were also prepared; their inherent properties and behavior in solution are discussed in the framework of thermal analysis and scanning electron microscopy inspection

Microesferas biodegradables de poli(D,L-láctico) conteniendo progesterona

Se obtuvieron microesferas de poli(D,L-láctico) conteniendo progesterona por medio de una emulsión simple aceite en agua empleando una técnica de evaporación de solvente. Se realizó un experimento con un diseño factorial 2 23 para estudiar el efecto de tres variables independientes (cantidad de principio activo, cantidad de polímero y concentración de alcohol polivinílico) sobre las variables dependientes (encapsulación de principio activo y tamaño de partícula). Las tres variables independientes influyeron significativamente sobre la encapsulación de progesterona. En el caso del tamaño de partícula, las variables que ejercieron una influencia significativa fueron la concentración de alcohol polivinílico y la cantidad de polímero. Los estudios de liberación in vitro han mostrado que de acuerdo al tamaño de partícula se pueden obtener formulaciones que logran liberar progesterona en pocos días u obtener una liberación sostenida durante 28 días. El estado físico del fármaco se investigó por calorimetría diferen- diferencial cial de barrido. Los estudios muestran que existe una interacción fisicoquímica entre la progesterona y el polímero