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.     

Oral administration of amphotericin B nanoparticles: antifungal activity,bioavailability and toxicity in rats

Amphotericin B (AMB) is used most commonly in severe systemic life-threatening fungal infections. There is currently an unmet need for an efficacious (AMB) formulation amenable to oral administration with better bioavailability and lower nephrotoxicity. Novel PEGylated polylactic-polyglycolic acid copolymer (PLGA-PEG) nanoparticles (NPs) formulations of AMB were therefore studied for their ability to kill Candida albicans (C. albicans). The antifungal activity of AMB formulations was assessed in C. albicans. Its bioavalability was investigated in nine groups of rats (n?=?6). Toxicity was examined by an in vitro blood hemolysis assay, and in vivo nephrotoxicity after single and multiple dosing for a week by blood urea nitrogen (BUN) and plasma creatinine (PCr) measurements. The MIC of AMB loaded to PLGA-PEG NPs against C. albicans was reduced two to threefold compared with free AMB. Novel oral AMB delivery loaded to PLGA-PEG NPs was markedly systemically available compared to Fungizone® in rats. The addition of 2% of GA to the AMB formulation significantly (p??790% that of Fungizone®. The novel AMB formulations showed minimal toxicity and better efficacy compared to Fungizone®. No nephrotoxicity in rats was detected after a week of multiple dosing of AMB NPs based on BUN and PCr, which remained at normal levels. An oral delivery system of AMB-loaded to PLGA-PEG NPs with better efficacy and minimal toxicity was formulated. The addition of glycyrrhizic acid (GA) to AMB NPs formulation resulted in a significant oral absorption and improved bioavailability in rats.     

Eudragit® microparticles as a possible tool for ophthalmic administration of acyclovir

This paper describes the production and characterization of polyacrylic polymer (Eudragit® RL, RS and NE) microparticles by spray drying method. Microparticles were designed for ophthalmic administration of acyclovir. Microparticle morphology was characterized by optical and electron microscopy. The release kinetics of the drug from microspheres were determined by a dialysis method. The spray drying method described allows the production of microparticles with acceptable encapsulation efficiency and appropriate dimensional characteristics for ophthalmic administration. Release profile data indicate that acyclovir is released from microparticles in a controlled manner. In addition the release pattern of the drug is influenced by the type of Eudragit® used for microparticle production. Moreover the plaque reduction efficiency of acyclovir containing microparticles (except for RS/NE microspheres) is comparable to that displayed by the free drug. Finally our results suggest that acyclovir containing microparticles could represent an interesting system for the release of this antiviral drug at the eye site.     

The penetration of amphotericin B from an Intralipid® formulation into fibrin loci in a rabbit model of candidiasis

The kinetics of amphotericin B (AMB) concentrations in plasma and interstitial fluid were studied in an experimental model of Candida albicans infection in rabbits. Rabbits were infected by subcutaneously implanted fibrin clots containing the yeast. Three groups of five rabbits received a 4 mg kg^?1 AMB infusion. AMB (Fungizone®) was dissolved in 5% glucose (group I) or in 20% Intralipid® at a final concentration of 1.5 (group II) or 3 mg mL^?1 (group III). AMB was measured by liquid chromatography in plasma and in trypsin-dissolved fibrin clots up to 72 h after the infusion. No significant differences in AMB plasma and interstitial-fluid concentration kinetics between the three modes of administration were found. AMB penetration into fibrin clots was slow, with no significant differences between treatments. Thus, formulation of AMB in Intralipid does not modify either the drug's interstitial or plasma kinetics at equivalent doses.     

Preparation of Polymeric Submicron Particle-Containing Microparticles Using a 4-Fluid Nozzle Spray Drier

Purpose We studied a novel method for preparing polymeric submicron particle-containing microparticles using a 4-fluid nozzle spray drier. Method Ethylcellulose (EC) and poly(lactic-co-glycolic acid) (PLGA), either alone or in combination with polyethylenimine (PEI), were used as polymers to produce submicron particles, and mannitol (MAN) was used as a water-soluble carrier for the microparticles. The polymer and MAN solutions were supplied through different liquid passages of a 4-fluid nozzle and then dried to obtain MAN microparticles containing EC or PLGA submicron particles. The polymer/MAN ratio was controlled by changing the concentration of the polymer and MAN solutions. EC or PLGA microparticles were observed via scanning electron microscopy, and the size of microparticles was determined by image analysis. The particle size distribution of EC or PLGA submicron particles was measured with a super dynamic light scattering spectrophotometer. Results The method generated submicron-sized (<1 μm) particles of EC and PLGA. The mean diameters of EC and PLGA particles at a polymer/MAN ratio of 1:10 were 631 and 490 nm, respectively. The mean diameter of PLGA particles decreased as the PLGA/MAN ratio was reduced, reaching ∼200 nm at a PLGA/MAN ratio of 1:100. The mean diameter of PLGA/PEI particles at PLGA/PEI/MAN ratios of 1:0.5:10 and 1:0.5:100 were 525 and 223 nm, respectively, and their zeta potentials were +50.8 and +58.2 mV, respectively. The size of EC submicron particles could be controlled by varying the spray conditions. Conclusions This study demonstrated that it is possible to prepare polymeric submicron particles dispersed in MAN microparticles in a single process using the 4-fluid nozzle spray drying method. Cationic PLGA particles with a diameter of ∼200 nm could be prepared by adding PEI, suggesting the possibility of its use as a carrier for delivering DNA into cells. The precipitation of EC may occur by the mutual dispersion and mixing of solvents after collision of EC and MAN mists by antisolvent effect, thereby producing MAN microparticles containing EC submicron particles.     

Preparation and characterization of biodegradable urea-loaded microparticles as an approach for transdermal delivery

This work describes the formulation and characterization of urea-loaded microspheres prepared using various polymers such as ethyl cellulose (EC), cellulose acetate phthalate (CAP) and poly (D,L-lactic-co-glycolic acid) (PLGA), along with the utilization of a solvent evaporation technique. The effect of various formulation parameters (i.e. polymer type and concentration, vehicle type, polymer solution/vehicle volume ratio, drug/polymer ratio, homogenizer and stirrer speed, sonication time and speed, type of washing solution, drying and separation method) on the characteristics of microspheres was also evaluated. Results obtained indicated that, in the presence of urea, highest rate of EC microsphere production could be obtained at a drug/polymer ratio of 1:2 and a polymer solution/vehicle volume ratio of 1:50. In some cases, crystallization of urea was observed during the encapsulation process using cellulose derivative polymers. CAP microparticles showed a rough and tortuous surface while EC microparticles had a wider range of particle size. However, with the PLGA polymer, much better desired microparticles with a smaller size range of 1-3 microm were obtained. In general, PLGA microspheres were spherical in shape and possessed smooth surfaces with less pores in comparison with those obtained by the other polymers. The yield of particle production and the extent of urea encapsulation in PLGA particles were measured to be 68.87% +/- 5.3 and 40.5% +/- 3.4, respectively. The release study from PLGA microspheres revealed that up to 70% of the drug was released within a few days, through a four-stage release pattern.     

Preparation and characterization of biodegradable urea-loaded microparticles as an approach for transdermal delivery

This work describes the formulation and characterization of urea-loaded microspheres prepared using various polymers such as ethyl cellulose (EC), cellulose acetate phthalate (CAP) and poly (D,L-lactic-co-glycolic acid) (PLGA), along with the utilization of a solvent evaporation technique. The effect of various formulation parameters (i.e. polymer type and concentration, vehicle type, polymer solution/vehicle volume ratio, drug/polymer ratio, homogenizer and stirrer speed, sonication time and speed, type of washing solution, drying and separation method) on the characteristics of microspheres was also evaluated. Results obtained indicated that, in the presence of urea, highest rate of EC microsphere production could be obtained at a drug/polymer ratio of 1:2 and a polymer solution/vehicle volume ratio of 1:50. In some cases, crystallization of urea was observed during the encapsulation process using cellulose derivative polymers. CAP microparticles showed a rough and tortuous surface while EC microparticles had a wider range of particle size. However, with the PLGA polymer, much better desired microparticles with a smaller size range of 1–3?µm were obtained. In general, PLGA microspheres were spherical in shape and possessed smooth surfaces with less pores in comparison with those obtained by the other polymers. The yield of particle production and the extent of urea encapsulation in PLGA particles were measured to be 68.87%?±?5.3 and 40.5%?±?3.4, respectively. The release study from PLGA microspheres revealed that up to 70% of the drug was released within a few days, through a four-stage release pattern.     

Peptide degradation during preparation and in vitro release testing of poly(l-lactic acid) and poly(dl-lactic-co-glycolic acid) microparticles

Biodegradable, tetracosactide-loaded microparticles were prepared by means of (i) spray drying, (ii) w/o/w solvent evaporation method (WOW) and (iii) by the aerosol solvent extraction system (ASES) using poly(l-lactic acid) (l-PLA) and poly(dl-lactic-co-glycolic acid) (dl-PLGA) of varying monomer composition or molecular weight. In the absence of the polymer the peptide did not degrade or aggregate irreversibly when in contact with methanol and methylene chloride or under the conditions used in the first step of WOW, as proven by HPLC, electrospray-mass spectrometry (MS) and circular dichroism (CD). During the extraction process, used to isolate the peptide from the microparticles, tetracosactide was partially oxidised. The highest stability of the peptide during microencapsulation was guaranteed with high molecular weight l-PLA, when using WOW or ASES, and with very low molecular weight PLGA, in the case of spray drying and WOW. The burst release of the microparticles, during in vitro release testing, depended on the preparation method as well as on the nature of the polymer and increased in the order ASES<spray drying<WOW and with increasing hydrophilicity of the polymer. Exceptionally, in the case of very low molecular weight PLGA, to which tetracosactide showed a very strong affinity during the in vitro adsorption study, no burst effect was observed. In addition, these microparticles released the peptide continuously, whereas for the others, composed of high molecular weight PLA and PLGA, the burst release was followed by a lag phase. During in vitro release peptide degradation increased with increasing polymer hydrophilicity but could be reduced by increasing drug loading. In polymer-free control solutions tetracosactide degradation was always slower than in the presence of microparticles. Oxidation and hydrolysis were found to be the major degradation pathways.     

Spray-Dried Chitosan Microparticles for Cellular Delivery of an Antigenic Protein: Physico-chemical Properties and Cellular Uptake by Dendritic Cells and Macrophages

Purpose

Spray-dried chitosan microparticles for cellular delivery of antigen to dendritic cells (DC) and macrophages (M?) were investigated.

Methods

Chitosan microparticles were prepared by spray drying. For comparison, poly(lactic-co-glycolic acid) (PLGA) and poly(α-butyl cyanoacrylate) (BCA) micro-/nanoparticles were generated. Bovine serum albumin (BSA) was used as a model antigen. The particles were characterized in terms of size, morphology, surface charge, surface composition, protein content, entrapment efficiency, in vitro release, and protein integrity. Additionally, they were subject to cell viability and cellular uptake study with DC and M?.

Results

Size of chitosan, PLGA, and BCA micro-/nanoparticles ranged between 3.11–7.18, 0.94–6.26, and 0.30–6.34 μm, respectively. Particle morphology and in vitro protein release varied, depending on polymer type, particle composition and preparation process parameters. Chitosan microparticles were cationic, while PLGA microparticles were neutral. BCA micro-/nanoparticles were either anionic or cationic, according to polymerization pH. Protein content and entrapment efficiency of chitosan and PLGA microparticles were relatively consistent. Only integrity and conformational structure of protein encapsulated in chitosan microparticles were completely retained. Chitosan and PLGA microparticles were non-toxic to DC and M?, but the former were internalized more efficiently.

Conclusions

Spray-dried chitosan microparticles delivered the antigen efficiently to DC and M?.     

Thermal behavior and stability of biodegradable spray-dried microparticles containing triamcinolone

Thermal analysis has been widely used for obtaining information about drug-polymer interactions and for pre-formulation studies of pharmaceutical dosage forms. In this work, biodegradable microparticles of poly (d,L-lactide-co-glycolide) (PLGA) containing triamcinolone (TR) in various drug:polymer ratios were produced by spray drying. The main purpose of this study was to study the effect of the spray-drying process not only on the drug-polymer interactions but also on the stability of microparticles using differential scanning calorimetry (DSC), thermogravimetry (TG) and derivative thermogravimetry (DTG), X-ray analysis (XRD), and infrared spectroscopy (IR). The evaluation of drug-polymer interactions and the pre-formulation studies were assessed using the DSC, TG and DTG, and IR. The quantitative analysis of drugs entrapped in PLGA microparticles was performed by the HPLC method. The results showed high levels of drug-loading efficiency for all used drug:polymer ratio, and the polymorph used for preparing the microparticles was the form B. The DSC and TG/DTG profiles for drug-loaded microparticles were very similar to those for the physical mixtures of the components. Therefore, a correlation between drug content and the structural and thermal properties of drug-loaded PLGA microparticles was established. These data indicate that the spray-drying technique does not affect the physico-chemical stability of the microparticle components. These results are in agreement with the IR analysis demonstrating that no significant chemical interaction occurs between TR and PLGA in both physical mixtures and microparticles. The results of the X-ray analysis are in agreement with the thermal analysis data showing that the amorphous form of TR prevails over a small fraction of crystalline phase of the drug also present in the TR-loaded microparticles. From the pre-formulation studies, we have found that the spray-drying methodology is an efficient process for obtaining TR-loaded PLGA microparticles.     

Controlled release behaviour of protein-loaded microparticles prepared via coaxial or emulsion electrospray

Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core–shell structure with mean diameters of 2.41?±?0.60?µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75?±?8.05?µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher (p?<?0.05) in the coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery.     

Controlled Release from Coated Polymer Microparticles Embedded in Tissue-engineered Scaffolds

The controlled release of proteins in tissue-engineered implants is being examined with the potential application to improve vascularization and hasten tissue growth. Bovine serum albumin (BSA), was encapsulated within poly(D,L-lactic-co-glycolic acid) [PLGA] microparticles. The microparticles were coated with poly(vinyl alcohol) and incorporated into PLGA tissue-engineered scaffolds during fabrication. The release of BSA from PLGA microparticles, coated PLGA microparticles, and microparticles embedded in a porous PLGA scaffold was measured. We have developed a novel approach that will permit incorporation of coated polymeric microparticles during PLGA scaffold fabrication. Growth factors or drugs could be incorporated into the microparticles resulting in a long-term, controlled release.     

Spray dried microparticles for controlled delivery of mupirocin calcium: Process–tailored modulation of drug release

Spray dried microparticles containing mupirocin calcium were designed as acrylic matrix carriers with modulated drug release for efficient local drug delivery at minimum daily dose. Particle generation in spray drying and its effect on release performance were assessed by varying drug?:?polymer ratios with consequently altered initial saturations. Narrow-sized microparticles with mean diameters of 1.7–2.5?µm were obtained. Properties of the generated solid dispersions were examined by X-ray, thermal (thermogravimetric analysis, modulated differential scanning calorimetry) and spectroscopic (Fourier transformed infrared, Fourier transformed Raman) methods and correlated with drug loading and in vitro release. The best control over mupirocin release was achieved for 2?:?1 (w/w) drug?:?polymer ratio and found to be strongly process-dependent. For a particular ratio, increased feed concentration (>4%) boosted while increased inlet temperature (≥100°C) reduced drug release. Antimicrobial activity testing confirmed that encapsulated drug preserved its antibacterial effectiveness. Conclusively, spray drying was proven as a suitable method for preparing structured microparticles which can control drug release even at exceptionally high drug loadings.     

Design and Development of a Novel Controlled Release PLGA Alginate-Pectinate Polyspheric Drug Delivery System

A 23 full factorial design was employed to evaluate and optimize the drug entrapment efficiency and in vitro drug release from PLGA microparticles encapsulated in a complex crosslinked alginate-pectinate matrix (polysphere). The independent formulation variables included the volume of internal and external phases, and concentration of PLGA. Surface morphology and internal structure of PLGA microparticles and polyspheres were examined by scanning electron microscopy which revealed spherical PLGA microparticles with highly porous surfaces that accounted for the rapid burst effect of this system. Texture analysis was used to profile the matrix resilience, tolerance, and energy absorbed. In vitro drug release was assessed in buffer media on PLGA microparticles and polyspheres. Polyspheres exhibited ideal zero-order release while PLGA microparticles had a burst effect followed by lag phase. Kinetic modeling of in vitro drug release data indicated that formulations were not highly dependent on polymeric erosion as a mechanism for drug release but rather diffusion. A close correlation existed between the matrix tolerance and energy absorbed. Formulations with decreased tolerance absorbed less energy, thus led to rapid surface erosion, lower matrix integrity and hence a burst effect. The converse was true for an increased matrix tolerance, which led to zero-order release supported by superior matrix integrity and a significantly reduced burst effect. The rat subcutaneous model validated in vitro release data and demonstrated that the polyspheres provided flexible yet superior rate-modulated drug delivery.     

Potential use of microencapsulation for sustained drug delivery to the respiratory tract.

Microencapsulation has long been regarded as a means of achieving sustained drug delivery. In these studies, a spray drying technique was used to produce salbutamol-loaded albumin microparticles with a view to formulating a controlled release system to be used in respiratory drug delivery. Encapsulation efficiencies (40-60 % w/w) obtained using this technique compared very favourably with those obtained using emulsification procedures (1-2 % w/w).     

Preparation of amorphous carvedilol polymeric microparticles for improvement of physicochemical properties

The aim of the present study was to enhance the physicochemical properties of poorly aqueous soluble carvedilol (CRV) by preparing its microparticles in presence and/or in absence of a hydrophilic carrier. The polymeric microparticles of CRV were prepared with polyvinylpyrrolidone K30 with or without addition of adsorbents like Aerosil^?200 and/or Sylysia^?350 by using spray drying technique. The dissolution profiles revealed that the drug and polymer ratio and colloidal silica both played critical role in solubility enhancement. The spray dried microparticles and drug alone were characterized by differential scanning calorimetry (DSC), X-ray powder diffraction, Fourier transformation infrared spectroscopy (FTIR), particle size analysis and scanning electron microscopy (SEM). DSC analysis showed that CRV transformed from the crystalline state to amorphous state by spray drying, confirmed by disappearance of its melting peak. The results of the X-ray analysis were in agreement with the thermal analysis data. It did not show characteristic crystalline drug peaks which confirmed that the amorphous form of CRV was present in the CRV loaded microparticles. FTIR analysis demonstrated hydrogen bonding interaction with an absence of significant chemical interaction between CRV and polymer. Spherical microparticles were yielded with smooth surfaces as observed by SEM. All in all, this work reveals that spray drying is a suitable technique for preparation of microparticles with improved physicochemical properties of CRV.     

Biodegradable Nanoparticles Improve Oral Bioavailability of Amphotericin B and Show Reduced Nephrotoxicity Compared to Intravenous Fungizone®

Purpose

Amphotericin B (AMB), an effective antifungal and antileishmanial agent associated with low oral bioavailability (0.3%) and severe nephrotoxicity, was entrapped into poly(lactide-co-glycolide) (PLGA) nanoparticles to improve the oral bioavailability and to minimize the adverse effects associated with it.

Materials and Methods

The AMB-nanoparticles (AMB-NP) were prepared by nanoprecipitation method employing Vitamin E-TPGS as a stabilizer. In vitro release was carried out using membrane dialysis method. The in vitro hemolytic activity of AMB-NP was evaluated by incubation with red blood cells (RBCs). The acute nephrotoxicity profile and oral bioavailability of AMB-NP were evaluated in rats.

Results

The prepared AMB-NP formulation contained monodispersed particles in the size range of 165.6?±?2.9 nm with 34.5?±?2.1% entrapment at 10% w/w initial drug loading. AMB-NP formulation showed biphasic drug release, an initial rapid release followed by a sustained release. The AMB-NP formulation exerted lower hemolysis and nephrotoxicity as compared to Fungizone®. The relative oral bioavailability of the AMB-NP was found to be ～800% as compared to Fungizone®.

Conclusion

Together, these results offer a possibility of treating systemic fungal infection and leishmaniasis with oral AMB-NP, which could revolutionize the infectious disease treatment modalities.

     

Water-free microencapsulation of proteins within PLGA microparticles by spray drying using PEG-assisted protein solubilization technique in organic solvent

Poly(d,l-lactic-co-glycolic acid) (PLGA) microparticles encapsulating therapeutic proteins were prepared under a water-free formulation condition. Bovine serum albumin (BSA) and recombinant human growth hormone (rhGH) were homogeneously solubilized as nano-scale complexes in methylene chloride phase by using polyethylene glycol (PEG) as a complex-forming agent. The organic phase containing dissolved PLGA and PEG/protein complexes was directly spray dried to obtain PLGA microparticles encapsulating proteins. They exhibited sustained release profiles of BSA and rhGH up to 30 days with reduced initial bursts. The released protein molecules from the microparticles maintained structural integrity without aggregation, suggesting that the current single-step protein microencapsulation method without using water could be potentially applied for sustained delivery of a wide range of therapeutic protein drugs that are not soluble in organic solvents.     

Controlled release pulmonary administration of curcumin using swellable biocompatible microparticles

This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nanoparticles and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of 221-243 nm and 3.1-3.9 μm, respectively. The developed carriers attained high swelling within a few minutes and showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor, and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in vitro TNF-α assays were performed for the investigated particles. These assays revealed promising biointeractions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery.     

Critical Solvent Properties Affecting the Particle Formation Process and Characteristics of Celecoxib-Loaded PLGA Microparticles via Spray-Drying

Purpose

It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying.

Methods

Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA).

Results

Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures.

Conclusions

The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.