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PubMedDate not supplied

Water-soluble betamethasone-loaded poly(lactide-co-glycolide) hollow microparticles as a sustained release dosage form.

In this study, betamethasone disodium phosphate-loaded microparticles were fabricated for sustained release using poly(lactide-co-glycolide) (PLGA) by spray drying and emulsion solvent evaporation/extraction techniques. Encapsulation efficiencies ranged from 59-80% using a water-in-oil-in-oil (W/O/O) double emulsion technique and more than 90% for a spray-drying method were obtained. This was a significant improvement compared to fabrication by a water-in-oil-in-water (W/O/W) double emulsion process, which had an encapsulation efficiency of less than 15%. Multiple-phase and biphasic release profiles were observed for microparticles of PLGA 50/50 and PLGA of higher lactide contents, respectively. The PLGA 50/50 hollow microparticles fabricated using the W/O/O double emulsion technique provided a sustained release of betamethasone disodium phosphate over 3 weeks.

Betamethasone↗
PubMedDate not supplied

Bovine serum albumin nanospheres carrying progesterone inclusion complexes.

Bovine serum albumin nanospheres carrying cyclodextrin complexes for the delivery of progesterone were produced. Inclusion complexes composed of progesterone and hydroxypropyl-beta-cyclodextrin or dimethyl-beta-cyclodextrin were prepared by spray-drying or freeze-drying methods. Prog alone and its inclusion complexes were incorporated into bovine serum albumin nanospheres using a coacervation method and cross-linking with heating. The nanosphere suspensions were essicated by spray-drying or freeze-drying. The inclusion complexes and the nanospheres were characterized by Fourier Transform-Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). Phase-solubility diagrams and stability constants were determined in distilled water at different temperatures (10, 25, and 37 degrees C). Size of nanospheres, their drug loading capacity and swelling ability were evaluated, as well as the in vitro controlled release profiles at pH 5.5 and 7.4.

Calorimetry, Differential Scanning↗
PubMed2005

Effect of vitamin E TPGS on immune response to nasally delivered diphtheria toxoid loaded poly(caprolactone) microparticles.

The nasal mucosa has many advantages as a potential site for drug and vaccine delivery. The present study has sought to exploit this route of delivery using microparticles composed of D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) as a matrix material blended with poly(caprolactone) for nasal immunisation with diphtheria toxoid. Particles were prepared by a double emulsion method, followed by spray drying and the effect of TPGS on size, zeta potential, loading and release of antigen was assessed. Particles composed of TPGS-PCL blends were spherical, smooth and monodisperse, displaying increasing yields after spray drying with increasing concentrations of TPGS. The immune response to diphtheria toxoid loaded PCL-TPGS microspheres after nasal administration was shown to be higher than that achieved using PCL microspheres alone. We conclude that TPGS shows significant potential as a novel adjuvant either alone or in combination with an appropriate delivery system.

Administration, Intranasal↗
PubMed2003

Improving relative bioavailability of dicumarol by reducing particle size and adding the adhesive poly(fumaric-co-sebacic) anhydride.

PURPOSE: This study was carried out to show the effect of particle size reduction and bioadhesion on the dissolution and relative bioavailability of dicumarol. METHODS: Formulations were produced by a variety of methods including a novel technique to reduce particle size as well as phase inversion with poly(fumaric-co-sebacic)anhydride p(FA:SA) to create nanospheres. Drug was administered to groups of pigs and rats via oral gavage of a suspension, and dicumarol concentration in the blood was measured using a double extraction technique. RESULTS: In vitro results showed improved dissolution in both the micronized formulation and the encapsulated p(FA:SA) nanospheres. In vivo, relative bioavailability of a spray-dried formulation was increased by 17% in the rat and 72% in the pig by further reduction in particle size. The bioadhesive p(FA:SA) formulation also improved relative bioavailability over the spray-dried drug, increasing it by 55% in the rat and 96% in the pig. Additionally, the p(FA:SA) formulation prolonged Tmax and decreased Cmax in both species. CONCLUSION: This work demonstrates the importance of particle size and bioadhesion to improve oral bioavailability of ducumarol.

Adhesives↗
PubMed2005

Phytostanol tablets reduce human LDL-cholesterol.

The feasibility of using solid dosage forms containing stanol lecithin to lower human LDL-cholesterol was investigated. The particle size distribution of a coarse aqueous dispersion of a stanol lecithin mixture was determined at various weight ratios of the components. At a stanol-to-lecithin weight ratio of 1.00-1.50, dispersions could be spray dried and the solid reconstituted with water to produce a particle size distribution that was similar to that of the aqueous dispersion from which it was derived. Two solid dosage forms containing this spray-dried stanol lecithin preparation had different disintegration times--tablets less than 10 min and capsules greater than 45 min. Each delivery system was then tested for LDL-cholesterol reduction activity in a placebo-controlled, double-blind clinical trial containing a total of 52 subjects. After a six-week treatment period, the group that received rapidly disintegrating stanol lecithin tablets (1.26 g stanols daily) experienced a decrease in both LDL-cholesterol and the ratio of LDL-cholesterol to HDL-cholesterol by 10.4% (P = 0.01) and 11.5% (P = 0.03), respectively, relative to placebo. On the other hand, with slowly disintegrating capsules (1.01 g daily) there was no statistically significant difference in any lipid parameter between the active group and placebo group. Taken together, these studies demonstrate that for maximum LDL-cholesterol reduction activity the stanol lecithin formulation must be delivered in a rapidly dispersible form to reach the site of cholesterol absorption.

Administration, Oral↗
PubMed1997

Study of the complexation behaviour of gliclazide with partially methylated beta-cyclodextrin in solution and solid state.

The complexation of Gliclazide (GL) with a partially methylated beta-cyclodextrin was studied. Phase-solubility and (1)H NMR spectroscopy were employed to investigate the complexation behaviour in solution and to demonstrate the complexation in liquid medium with the participation of both azabicyclooctyl and tolyl moieties of GL in the inclusion process. Solid systems prepared by kneading, co-grinding and spray drying have also been checked, using DSC and HSM, for assessing the formation of the inclusion compound. Experimental evidence of the complexation between drug and cyclodextrin was reported for the co-ground and spray-dried systems.

Journal Article↗
PubMed2005

Influence of the vehicle on the properties and efficacy of microparticles containing amphotericin B.

New microparticles containing amphotericin B (AMB) have been developed and manufactured by spray drying. To this end albumin, polylactic-co-glycolic acids (PLGA) and poly(sebacic anhydride) have been employed as drug carriers. The selection of the solvent used to disperse the drug and the vehicle before spray drying was critical on production yields and physical properties of the microparticles. Once particle size, morphology and dispersability in some aqueous media were shown to be acceptable for an intravenous administration, in vivo efficacy was evaluated and compared with the reference medicine Fungizone. Microparticles prepared with albumin, albumin heated at a high temperature, some kinds of PLGA or polyanhydride, as well as Fungizone, were tested in an experimental hamster model of infection with Leishmania infantum, by evaluating the evolution of parasitic burdens in spleen, liver and antibody responses. After the injection of three doses corresponding to 2 mg of AMB per kilogram each, diverse reactions were reported depending on the vehicle. The best dispersability, reduction of parasites and antibody response were achieved when the treatment was performed with AMB in albumin microspheres.

Albumins↗
PubMed2004

Rational design of solid aerosols for immunoglobulin delivery by modulation of aerodynamic and release characteristics.

Parenteral administration of immunoglobulins (Ig) for prevention or treatment of respiratory diseases achieves only modest concentrations of antibody in the pulmonary interstitial tissue and airways. Aerosols, including spray-dried particles, must overcome two limiting factors in order to be effective vehicles for pulmonary delivery of Ig: (i) Fc receptor (FcR)-mediated scavenging by macrophages and (ii) clearance by the mucociliary system. Ig-incorporated spray-dried lipid microparticles (SDLM), coformulated with or without a biocompatible surfactant (1% w:w) to modulate protein release, were designed and tested for their capability to deliver Ig to the respiratory tract. To determine efficacy, rodents were immunized with SDLM containing antiinfluenza antibody followed by virus challenge and clinical parameters measured. Control of the release kinetics resulted in enhanced delivery of immunoglobulins to the respiratory tract and interstitial tissue with slow translocation into the systemic circulation. As much as 60% of the IgG delivered from nonretentive SDLM could be recovered from the lung interstitial tissue within 1 h after aerosol administration at a dose of 1 mg of Ig/kg of body weight. In addition, nonretentive rather than slow-release particles loaded with antiinfluenza antibody were effective in curbing virus replication with a resulting positive clinical outcome. Thus, controlled release of Ig by manipulating aerosol characteristics and composition allows for a significant increase in the efficiency of pulmonary delivery of antibodies.

Administration, Inhalation↗
PubMed1998

Plasma protein adsorption on biodegradable microspheres consisting of poly(D,L-lactide-co-glycolide), poly(L-lactide) or ABA triblock copolymers containing poly(oxyethylene). Influence of production method and polymer composition.

Biodegradable particulate systems have been considered as parenteral drug delivery systems. The adsorption of plasma proteins on micro- and nanoparticles is determined by the surface properties and may, in turn, strongly influence the biocompatibility and biodistribution of both carriers. In the present study the influence of the polymer composition and the production method of microspheres on the in vitro plasma protein adsorption were investigated using two-dimensional electrophoresis (2-DE). Microparticles were prepared from poly(l-lactide) (l-PLA), poly(d,l-lactide-co-glycolide) (PLGA), and ABA triblock copolymers containing hydrophilic poly(oxyethylene) (B-blocks) domains connected to hydrophobic polyesters (A-blocks). Two different microencapsulation methods were employed, namely the w/o/w emulsion solvent evaporation method and the spray-drying technique. It could be demonstrated that the polymer composition and, especially, the encapsulation technique, influenced the interactions with plasma proteins significantly. For example, the percentages of several apolipoproteins in the plasma protein adsorption patterns of spray-dried PLGA- and l-PLA-particles were distinctly higher when compared to the adsorption patterns of the particles produced by the w/o/w-technique. Some adsorbed proteins were found to be characteristic or even specific for particles produced by the same method or consisting of identical polymers. Polyvinyl alcohol used as stabilizer in the w/o/w-technique may decisively influence the surface properties relevant for protein adsorption. The plasma protein adsorption on particles composed of ABA copolymers was drastically reduced when compared to microspheres made from pure polyesters. The adsorption patterns of ABA-particles were dominated by albumin. The plasma protein adsorption patterns detected on the different microspheres are likely to affect their in vivo performance as parenteral drug delivery systems.

Adsorption↗
PubMed1992

[Relationships between manufacturing parameters and pharmaceutical-technological requirements of biodegradable microparticles. 2. Preparation of injectable microparticles in biodegradable polyester].

Local anesthetics containing biodegradable polyester microparticles are prepared using a modified solvent-evaporation process and a spray drying technique. The preparation methods are compared critically. The modified solvent-evaporation process is preferred for the preparation of microparticles. Yields of 90% and microparticle size distributions can be influenced in a reproducible manner. Using the spray drying technique yields are only 60%. The product is characterized by a high portion of microparticles under 10 microns, which are responsible for the rapid release of cinchocain in 168 h as well.

Anesthetics, Local↗
PubMed2006

Manufacture, characterization, and pharmacodynamic evaluation of engineered ipratropium bromide particles.

PURPOSE: The intent of this research was to generate and characterize respirable particles of ipratropium bromide (IPB), a short-acting anticholinergic bronchodilator, to achieve demonstrable sustained-release properties. The value of a long-acting anticholinergic agent is evident in the use of tiotropium for the treatment of chronic obstructive pulmonary disease. METHODS: Hollow, spherical particles of ipratropium bromide suitable for inhalation were generated using a spray-drying process and characterized by laser diffraction particle size analysis, scanning electron microscopy, dynamic vapor sorption, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and dissolution testing. Experimental design techniques were used to identify critical process parameters and optimize the spray drying process. Pharmacodynamic studies were conducted to determine duration of effect. RESULTS: Crystalline, stable, respirable particles with a range of dissolution profiles were manufactured by application of polylactic acid (PLA) coatings of 1, 5, 10, 15, 30, and 50% w/w. A novel, robust, modified Type IV dissolution method discriminated between formulations and guided their development. Preliminary studies in guinea pigs indicated an increased duration of bronchodilatory effect for 30% PLA-coated particles (56.3 min) particles compared with IPB powders alone (11.0 min). CONCLUSIONS: Sustained-release respirable particles of ipratropium bromide were developed using a PLA spray coating approach and a trend for increased duration of effect was demonstrated in guinea pigs.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2006

Rapid assessment of the structural relaxation behavior of amorphous pharmaceutical solids: effect of residual water on molecular mobility.

PURPOSE: Use RH-perfusion microcalorimetry and other analytical techniques to measure the interactions between water vapor and amorphous pharmaceutical solids; use these measurements and a mathematical model to provide a mechanistic understanding of observed calorimetric events. MATERIALS: Isothermal microcalorimetry was used to characterize interactions of water vapor with a model amorphous system, spray-dried raffinose. Differential scanning calorimetry was used to measure glass transition temperature, T (g). High-sensitivity differential scanning calorimetry was used to measure enthalpy relaxation. X-ray powder diffraction (XRPD) was used to confirm that the spray-dried samples were amorphous. Scanning electron microscopy (SEM) was used to examine particle morphology. Gravimetric vapor sorption was used to measure moisture sorption isotherms. Thermogravimetric analysis (TGA) was used to measure loss on drying. RESULTS: A moisture-induced thermal activity trace (MITAT) provides a rapid measure of the dependence of molecular mobility on moisture content at a given storage temperature. At some relative humidity threshold, RH(m), the MITAT exhibits a dramatic increase in the calorimetric rate of heat flux. Simulations using calorimetric data indicate that this thermal event is a consequence of enthalpy relaxation. CONCLUSIONS: RH-perfusion microcalorimetry is a useful tool to determine the onset of moisture-induced physical instability of glassy pharmaceuticals and could find a broad application to determine appropriate storage conditions to ensure long-term physical stability. Remarkably, thermal events measured on practical laboratory timescales (hours to days) are relevant to the stability of amorphous materials on much longer, pharmaceutically relevant timescales (years). The mechanistic understanding of these observations in terms of enthalpy relaxation has added further value to the use of RH-perfusion calorimetry as a rapid means to characterize the molecular mobility of amorphous solids.

Adsorption↗
PubMed2003

Design of physostigmine-loaded polymeric microparticles for pretreatment against exposure to organophosphate agents.

Physostigmine is an anti-cholinesterase used for the pretreatment of a poisoning caused by highly toxic organophosphorus neurotoxins. The aim of this study is to design a polymeric microparticle system for sustained release of physostigmine. In this paper, we have attempted to encapsulate physostigmine in microparticles made from poly(D,L-lactide-co-glycolide) (PLGA) with various contents of glycolide and poly(D,L-lactide) (PLA) using spray-drying and single emulsion techniques. It was found that during the single emulsion process, most of the physostigmine molecules were lost in the external aqueous phase. However, more than 90% encapsulation efficiency of physostigmine was obtained using the spray-drying technique. SEM micrographs revealed that spherical microparticles containing physostigmine with a smooth surface were yielded with PLA, PLGA 50:50, RG 502 (PLGA 50:50 with a lower molecular weight) and PLGA 65:35 but PLGA 85:15, PLGA 75:25 and PLGA 50:50 with a high concentration produced microparticles with irregular shapes. An increased inlet temperature yielded a higher physostigmine release rate from the PLA microparticles. Physostigmine release from the microparticles showed a biphasic pattern, characterized by an initial burst release followed by a sustained release for PLGA 65:35, PLGA 50:50 and RG 502 or a non-detectable release for PLGA 85:15, PLGA 75:25 and PLA. A sustained-release of physostigmine with a low initial burst over 1 week was achieved from RG 502 microparticles, which would be used as an injectable dosage form in our further animal studies.

Biopolymers↗
PubMed2004

Determining the critical relative humidity for moisture-induced phase transitions.

A new method to determine the onset relative humidity for a glass transition and crystallization processes in amorphous or partially amorphous materials was developed using dynamic gravimetric vapor sorption (DVS). Water vapor can act as a plasticizing agent in amorphous materials, thus lowering the glass transition temperature below room temperatures. Additional water sorption can lead to a crystallization event below the glass transition temperature. On spray-dried lactose the glass transition RH and crystallization RH values were 30 and 58% at 25 degrees C, respectively. Glass transition and crystallization RH values were also measured at 5, 15, 25, 35, and 45 degrees C on a spray-dried salbutamol sulfate sample. The glass transition RH values for the salbutamol sulfate sample ranged from 64.5% RH (5 degrees C) to 32.8% RH (45 degrees C) while the crystallization RH values ranged from 81.0% RH (5 degrees C) to 50.4% RH (45 degrees C). The results clearly show that the glass transition and crystallization humidity values decrease as the sample temperature increases.

Albuterol↗
PubMed2002

Sustained delivery of human growth hormone from a novel gel system: SABER.

PURPOSE: The purpose of this study was to evaluate the release of recombinant human growth hormone (rhGH) from a novel non-polymeric sustained release system, SABER. METHODS: The SABER system consists of sucrose acetate isobutryate, a solvent and a polymeric release modifier. Spray dried formulations of zinc complexed rhGH in sodium bicarbonate containing sucrose and polysorbate 20 were homogenized with various SABER systems (10% w/v rhGH) and assessed in vitro and in vivo (rat studies). The effect of protein to sucrose ratio in the spray dried formulation and a release modifier, poly-D,L-lactic acid (PLA), in the SABER system, on the initial release was investigated along with the effect of dose volume. RESULTS: The in vitro release studies with rhGH SABER suspensions indicate that increasing the sucrose content from 2 to 5 mg/ml in the rhGH formulations increased the initial release (24 h) from 78.0% to 93.5%. When the protein formulation was held constant and 1.0% w/w PLA was added to the solvent phase, the initial release was reduced from 78.0% to less than 5.0%. The initial release in vivo after subcutaneous administration (SC) in rats (15 mg/kg rhGH) decreased with increasing PLA content (1.0% w/w PLA, Cmax = 342.8 ng/ml; 10% w/w PLA, Cmax = 35.4 ng/ml), while increased sucrose content increased both the initial release (AUC(0-2) days) and persistence (AUC(2-7) days) over the 7 days from 64.2 to 228.4 ng day/ml (total AUC). A linear dose response (rhGH serum levels) was observed after SC administration of different rhGH SABER volumes greater than 100 microl. Histological examination of the injection sites indicated a mild inflammatory response similar to that observed after injection of PLA microspheres. CONCLUSIONS: The addition of PLA reduced the initial release rate of protein release from SABER, while increasing the sucrose content of the protein formulation yielded increased rhGH persistence. These results demonstrate that the SABER delivery system allows weight-based dosing at volumes greater than 100 microl to achieve sustained release of intact rhGH in vivo for at least 7 days.

Animals↗
PubMed2006

Enhancement in dissolution pattern of piribedil by molecular encapsulation with beta-cyclodextrin.

The aim of this study was to improve the dissolution behavior of piribedil by molecular encapsulation with beta-cyclodextrin (beta-CD). Toward this aim, physical mixing, co-grinding, and spray-drying methods were used to prepare solid binary systems. Differential scanning calorimetry, X-ray diffractometry, and particle size analysis were used to characterize the binary systems obtained. Complexes of piribedil and beta-CD could be prepared using the spray-drying method. Dissolution of piribedil was improved to a great extent by the complex prepared.

Antiparkinson Agents↗
PubMed1979

Anaphylactic sensitivity of guinea-pigs drinking different preparations of cows' milk and infant formulae.

Guinea-pigs have been given various preparations of cows' milk or infant formulae to drink in an investigation of the capacity of these milk preparations to stimulate per os anaphylactic sensitivity. The treatment, presumably heat, used to concentrate the 'Evaporated' whole cows' milks (three brands were tested) almost abolished their sensitizing capacity to beta lactoglobulin. The brand presumed to be most heated as judged by the degree of caramelization had also lost most of its sensitizing capacity to casein. Injected parenterally, the 'Evaporated' milk adequately sensitized to anaphylaxis. An infant formula, which in its spray dried form was only moderately sensitizing to both beta lactoglobulin and casein, lost most of this sensitizing capacity when processed to a liquid concentrate state. The manufacturing process for the liquid concentrate involved greater and more prolonged heating than required for the spray-dried form. The relevance of these findings in the guinea-pig to cows' milk protein intolerance in the infant and possibly also to cot death is discussed.

Anaphylaxis↗
PubMed2006

Retention of a European pear aroma model mixture using different types of saccharides.

Eight types of microcapsules of European pear (La France) aroma model mixture were prepared, and their retained aroma components and sample microstructures (both surface and cross-section) were compared. The La France pear aroma model mixture was prepared by the mixing of hexanal and five kinds of esters. alpha-Cyclodextrin (alpha-CD), gum arabic (GA), soybean soluble polysaccharide (SSPS), and highly branched cyclic dextrin (HBCD) were used as carrier solids, and spray drying and freeze drying comprised the drying methods. The mean particle size of the microcapsules ranged from 8.34 microm for the microcapsules with alpha-CD to 9.67 microm for those with SSPS. The total aroma contents were different depending upon the microencapsulation systems (1.35 g/100 g of microcapsules for the spray-dried microcapsules with HBCD to 14.1 g/100 g of microcapsules for the freeze-dried microcapsules with GA). The microcapsules with alpha-CD and GA were stable against heat treatment (40, 80, or 120 degrees C for 60 min) under nitrogen gas flow.

Aldehydes↗