Preparation and characterization of spray-dried valsartan-loaded Eudragit® E PO solid dispersion microparticles

The purpose of this study was to develop the immediate release stomach-specific spray-dried formulation of valsartan (VAL) using Eudragit^® E PO (EPO) as the carrier for enhancing dissolution rate in a gastric environment. Enhanced solubility and dissolution in gastric pH was achieved by formulating the solid dispersion using a spray drying technique. Different combinations of drug–polymer–surfactant were dissolved in 10% ethanol solution and spray-dried in order to obtain solid dispersion microparticles. Use of the VAL–EPO solid dispersion microparticles resulted in significant improvement of the dissolution rate of the drug at pH 1.2 and pH 4.0, compared to the free drug powder and the commercial product. A hard gelatin capsule was filled with the VAL–EPO solid dispersion powder prior to the dissolution test. The increased dissolution of VAL from solid dispersion microparticles in gastric pH was attributed to the effect of EPO and most importantly the transformation of crystalline drugs to amorphous solid dispersion powder, which was clearly shown by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (P-XRD) studies. Thus, VAL, a potential antihypertensive drug in the form of a solid dispersion microparticulate powder, can be effectively delivered in the immediate release dosage form for stomach-specific drug delivery.     

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.     

Silymarin-solid dispersions: characterization and influence of preparation methods on dissolution

The influence of preparation methodology of silymarin solid dispersions using a hydrophilic polymer on the dissolution performance of silymarin was investigated. Silymarin solid dispersions were prepared using HPMC E 15LV by kneading, spray drying and co-precipitation methods and characterized by FTIR, DSC, XRPD and SEM. Dissolution profiles were compared by statistical and model independent methods. The FTIR and DSC studies revealed weak hydrogen bond formation between the drug and polymer, while XRPD and SEM confirmed the amorphous nature of the drug in co-precipitated solid dispersion. Enhanced dissolution compared to pure drug was found in the following order: co-precipitation > spray drying > kneading methodology (p < 0.05). All preparation methods enhanced silymarin dissolution from solid dispersions of different characteristics. The co-precipitation method proved to be best and provided a stable amorphous solid dispersion with 2.5 improved dissolution compared to the pure drug.     

Characterisation of excipient-free nanoporous microparticles (NPMPs) of bendroflumethiazide.

The purpose of this study was to prepare excipient-free porous microparticles of bendroflumethiazide by spray drying and to characterise the physicochemical properties of the particles produced. Solutions of bendroflumethiazide in ethanol/water, ethanol/water/ammonium carbonate or methanol/water/ammonium carbonate were spray dried using a laboratory spray dryer. Spray dried products were characterised by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimetry, FTIR, laser diffraction particle sizing and density measurement. Nanoporous microparticles (NPMPs) were prepared from the alcoholic solutions containing ammonium carbonate. NPMPs were amorphous in nature, had median particles sizes less than 3mum and densities that were significantly reduced compared to non-porous spray dried bendroflumethiazide powder. The novel process may be used to produce excipient-free amorphous microparticles with desirable physical properties such as amorphous solid state, porosity and low bulk density. This new engineering technology has applications in the design of other therapeutic agents such as those used in pulmonary delivery.     

穿心莲内酯聚丙烯酸树脂Ⅱ固体分散体的制备及表征

目的：研究无定形聚合物聚丙烯酸树脂Ⅱ（Eudragit Ⅱ）制备的穿心莲内酯固体分散体的优良性质,为固体分散体的载体选择提供参考依据。方法：以无定形聚合物Eudragit Ⅱ为载体材料,按穿心莲内酯-载体质量比为1：3,采用喷雾干燥法制备穿心莲内酯固体分散体,并用傅里叶变换红外光谱（FTIR）、热重分析（TG）、X-射线衍射（XRD）、差示扫描量热（DSC）、扫描电镜（SEM）、比表面积、粒径和溶出度测定穿心莲内酯固体分散体的理化性质及溶出行为。结果：FTIR光谱和TG分析说明在穿心莲内酯固体分散体和物理混合物中穿心莲内酯与Eudragit Ⅱ之间都存在分子间相互作用,其中穿心莲固体分散体具有更好的热稳定性;DSC和XRD分析说明无定形载体Eudragit Ⅱ制备的固体分散体中穿心莲内酯主要以无定形形式存在;SEM显示,固体分散体中穿心莲内酯由块状晶体形态变为了不规则的圆形形态;同时与物理混合物相比,穿心莲内酯固体分散体具有更大的比表面积、更大的孔体积和更小的粒径等粉体学性质;溶出实验表明穿心莲内酯固体分散体具有增大溶出的优势,效果明显。结论：以无定形载体Eudragit Ⅱ制备的穿心莲内酯固体分散体具有优良的理化性质,同时比表面积大,孔体积大的特征更有利于水分子的进入,从而有效地增大穿心莲内酯的溶出速率。     

Physicochemical characterization and dissolution properties of meloxicam-gelucire 50/13 binary systems

A solid dispersion of Meloxicam (MX), a poorly soluble, non steroidal anti-inflammatory drug, and Gelucire 50/13 was prepared by spray drying. Spherical microparticles were yielded with smooth surfaces as observed by scanning electron microscopy. According to differential scanning calorimetry and powder X-ray diffractometry analysis, MX was transformed from the crystalline state to the amorphous state as confirmed by the disappearance of its melting peak and the crystalline peaks. The dissolution tests at pH 7.4 revealed that the dissolution rate of encapsulated MX was 2.5-fold higher than that of the corresponding physical mixture and fourfold higher than the drug alone, respectively. The microparticles prepared at a ratio of 1:4 (drug/Gelucire) exhibited a 4-fold higher anti-inflammatory activity on the paw edema of rats in comparison to the drug alone. All in all, this work reveals that spray drying is a suitable technique for preparation of solid dispersions with improved biopharmaceutical and pharmacological characteristics of MX.     

Evaluation of Spironolactone Solid Dispersions Prepared by Co-Spray Drying With Soluplus® and Polyvinylpyrrolidone and Influence of Tableting on Drug Release

Solid dispersions of spironolactone with Soluplus^® and polyvinylpyrrolidone were prepared by spray drying according to a mixture experimental design and evaluated for moisture content, particle size, drug solubility, crystallinity (powder X-ray diffraction and differential scanning calorimetry), and physicochemical interactions (Fourier-transform infrared spectroscopy, Raman). In vitro dissolution was evaluated for the spray dried product itself and after compression into tablets, and prediction models were derived using multiple linear regression analysis. The spray dried products consisted of amorphous drug, indicated by the absence of crystalline powder X-ray diffraction peaks. Amorphization and interactions impacted changes in the Fourier-transform infrared spectroscopy spectra in the ranges 2900-3000 cm^?1 (C-H) and 1600-1800 cm^?1 (C=O) and caused merging at 1690 cm^?1 (C=O of lactone) and 1670 cm^?1 (C=O of thioacetyl group). In the Raman spectra, amorphization and interactions resulted in disappearance of peak at 1690 cm^?1 (C=O) and merging of peaks at 582 and 600 cm^?1 (C-S). Hydrogen bonding between the thioacetyl group of the drug with the hydroxyl groups of Soluplus^® caused marked suppression of the peak at 1190 cm^?1 (R-C(=O)-S vibration). Amorphization and interactions resulted in improved solubility and dissolution which was greatest for drug/Soluplus^® ratio 1:4 and was also demonstrated in the corresponding tablets.     

Physicochemical characterization of tacrolimus-loaded solid dispersion with sodium carboxylmethyl cellulose and sodium lauryl sulfate

To develop a novel tacrolimus-loaded solid dispersion with improved solubility, various solid dispersions were prepared with various ratios of water, sodium lauryl sulfate, citric acid and carboxylmethylcellulose-Na using spray drying technique. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy, differential scanning calorimetery and powder X-ray diffraction. Furthermore, their solubility and dissolution were evaluated compared to drug powder. The solid dispersion at the tacrolimus/CMC-Na/sodium lauryl sulfate/citric acid ratio of 3/24/3/0.2 significantly improved the drug solubility and dissolution compared to powder. The scanning electron microscopy result suggested that carriers might be attached to the surface of drug in this solid dispersion. Unlike traditional solid dispersion systems, the crystal form of drug in this solid dispersion could not be converted to amorphous form, which was confirmed by the analysis of DSC and powder X-ray diffraction. Thus, the solid dispersion system with water, sodium lauryl sulfate, citric acid and CMC-Na should be a potential candidate for delivering a poorly water-soluble tacrolimus with enhanced solubility and no convertible crystalline.     

Effects of Kollicoat IR® and hydroxypropyl-β-cyclodextrin on the dissolution rate of omeprazole from its microparticles and enteric-coated capsules

Omeprazole microparticles were prepared by different drying techniques using Kollicoat IR^® and hydroxypropyl-β-cyclodextrin hydrophilic polymers. Physico-chemical properties were investigated using differential scanning calorimetry and powder X-ray diffractometry. Dissolution rate was determined and compared to the physical mixtures and the morphology was studied using a scanning electron microscope. Omeprazole transformed from the crystalline state to the amorphous state as confirmed by the disappearance of its melting peak and the characteristic of the crystalline peaks. Omeprazole dissolution rate was enhanced significantly from its spray- and freeze-dried microparticles as compared to the corresponding physical mixtures and drug alone (P?<?0.05). F3 and F5 formula possessed superior release rate over other formulations. In acidic medium, the release of drug from enteric-coated capsules was not detectable, while it is completely released within 40?min after changing dissolution medium to phosphate buffer (pH 7.4). The transformation of OME from crystalline to amorphous state by using either Kollicoat IR^® or hydroxylpropyl-β-cyclodextrin is considered a promising way to improvement of drug dissolution.     

Formulating Inhalable Dry Powders Using Two-Fluid and Three-Fluid Nozzle Spray Drying

Purpose

The spray drying process is widely applied for pharmaceutical particle engineering. The purpose of this study was to investigate advantages and disadvantages of two-fluid nozzle and three-fluid nozzle spray drying processes to formulate inhalable dry powders.

Methods

Budesonide nanocomposite microparticles (BNMs) were prepared by co-spray drying of budesonide nanocrystals suspended in an aqueous mannitol solution by using a two-fluid nozzle spray drying process. Budesonide-mannitol microparticles (BMMs) were prepared by concomitant spray drying of a budesonide solution and an aqueous mannitol solution using a spray drier equipped with a three-fluid nozzle. The resulting dry powders were characterized by using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Raman microscopy. A Next Generation Impactor was used to evaluate the aerodynamic performance of the dry powders.

Results

XRPD and DMA results showed that budesonide remained crystalline in the BNMs, whereas budesonide was amorphous in the BMMs. Spray drying of mannitol into microparticles resulted in a crystalline transformation of mannitol, evident from XRPD, DSC and Raman spectroscopy analyses. Both BMMs and BNMs displayed a faster dissolution rate than bulk budesonide. The yield of BNMs was higher than that of BMMs. The mass ratio between budesonide and mannitol was preserved in the BNMs, whereas the mass ratio in the BMMs was higher than the theoretical ratio.

Conclusions

Spray drying is an enabling technique for preparation of budesonide amorphous solid dispersions and nanocrystal-embedded microparticles. Two-fluid nozzle spray drying is superior to three-fluid nozzle spray drying in terms of yield.

     

Spray drying of budesonide, formoterol fumarate and their composites--I. Physicochemical characterisation

The objective of this work was to examine the physicochemical properties of spray dried budesonide, formoterol fumarate and their mixtures at two different weight ratios: 100:6 and 400:6 of budesonide and formoterol fumarate, respectively. A comparison of the thermal properties, crystalline/amorphous nature and particle size of the starting micronised as well as processed materials was carried out. The micronised drugs on their own and the physical mixtures were crystalline in contrast to the spray dried counterparts which were shown to be amorphous. The glass transition temperatures (T(g)s) of the processed actives were determined and appeared at 89.5 and 88 degrees C for budesonide and formoterol fumarate, respectively. As for the spray dried composites, an indication of miscibility and/or interactions between the components was indicated by differential scanning calorimetry and infrared analysis. The spray drying in all cases resulted in smooth, spherical microparticles of sizes suitable for inhalation.     

Complexation of celecoxib with beta-cyclodextrin: characterization of the interaction in solution and in solid state

Inclusion complexation between celecoxib, a specific cyclooxygenase II inhibitor, and beta-cyclodextrin (beta-CD) was studied in solution and solid state. Drug cyclodextrin complexes were prepared by spray drying while physical mixtures were obtained by simple blending. Inclusion complexes were characterized by nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), and polarimetry. Phase solubility analysis was carried out to determine the stability constant. Solubility studies revealed the existence of a 1:1 complex between celecoxib and beta-CD. NMR studies suggested a strong interaction between celecoxib and beta-CD prepared by spray drying. XRD and SEM analysis illustrated that celecoxib existed as an amorphous complexed form in spray-dried complexes. Dissolution studies showed that the celecoxib entrapped in spray-dried complexes dissolved much faster than the uncomplexed drug and physical mixtures. The data obtained suggest that celecoxib forms an inclusion complex with beta-CD in solution and solid state, which was confirmed by various analytical techniques. A shorter t50% of dissolution is found for the formulation prepared by spray drying when compared on a weight basis in a USP II apparatus.     

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.     

Enhancement of Solubility and Dissolution Rate of Loratadine with Gelucire 50/13

The objective of the current investigation was to enhance the solubility and dissolution rate of loratadine using solid dispersions (SDs) with Gelucire 50/13. SDs of loratadine using Gelucire 50/13 as carrier were prepared by the solvent evaporation method, characterized for drug content, dissolution behavior, and physicochemical characteristics by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) studies. At 10 % concentration of Gelucire 50/13, the increase in solubility was around 100-fold compared with pure drug. The solubility of loratadine in the presence of Gelucire 50/13 in water showed linear increase with increasing concentrations of Gelucire indicating A_L-type solubility diagrams. The mean dissolution time (MDT) of loratadine decreased after preparation of SDs with Gelucire 50/13 indicating increased dissolution rate. FTIR studies showed the stability of loratadine and the absence of a well-defined interaction. DSC and XRD studies revealed the amorphous state of loratadine in SDs which was further confirmed from SEM. From the dissolution parameters, it is evident that the solubility and dissolution rate of loratadine was enhanced by SDs with Gelucire 50/13.     

Ivermectin-loaded microparticles for parenteral sustained release: in vitro characterization and effect of some formulation variables

Ivermectin (IVM) is a BCS II drug with potent antiparasitic activity in veterinary applications. In this study, poly(lactide-co-glycolide) (PLGA) and poly(DL-lactide) (PLA) Ivermectin-loaded microparticles were prepared by the simple emulsion (O/W) solvent evaporation method in order to obtain sustained release formulations for parenteral applications. The effects of polymer end-groups (ester or free acid) and the addition of the hydrophilic polyvinylpyrrolidone polymer (PVP) in in vitro drug release profiles were also studied. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis showed that IVM was present in an amorphous state or as a molecular dispersion within the polymers or theirs mixtures with PVP and that a PVP-drug complex was formed. Drug entrapment efficiency in the microparticles (>90%) was independent of the polymer composition, the end groups and the presence of PVP. However, microscopic (SEM) observations showed that the addition of PVP led to more porous microparticles accompanied by the increased rates of drug release.     

Supramolecular organization and release properties of phospholipid-hyaluronan microparticles encapsulating dexamethasone

We describe the supramolecular organization of hybrid microparticles encapsulating dexamethasone (DXM) prepared by spray drying 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC) and hyaluronic acid (HA). The effect of DXM concentration on size distribution and encapsulation efficacy was evaluated as a function of HA concentration. In the absence of HA, DXM leads to a strong particle aggregation, whereas in the presence of HA, the aggregation is practically suppressed. DXM percentage of encapsulation is high (95+/-6%), independently of composition. Drug-excipient interactions were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction. DSC demonstrates that only a small fraction of DXM interacts with DPPC, whereas X-ray diffraction does not detect this interaction. Finally, in vitro release studies show that HA does not influence DXM release kinetics. In all cases, a burst release of DXM is observed during the first hour. Under sink conditions, powder concentration in the release medium governs the extent of the burst. Under non sink conditions, DXM release is mostly governed by DXM solubility in the release medium. In the dry microparticles, DXM is probably mostly in amorphous domains within the DPPC-HA matrix. Upon hydration, the majority of the drug is released and only a small amount of DXM interacts with DPPC.     

Enhanced solubility and dissolution of simvastatin by HPMC-based solid dispersions prepared by hot melt extrusion and spray-drying method

The objective of this study was to use low viscosity grade hydroxypropyl methyl cellulose (Methocel^® E3 LV and Methocel^® E5 LV) to enhance the solubility and dissolution of poorly water soluble drug simvastatin (SIM). Two different technologies, hot melt extrusion and spray drying were employed. Characterization of hot melt extrudes and spray dried samples was done by Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction studies and scanning electron microscopy. The result of the study showed the conversion of crystalline form drug into amorphous form indicating increase in dissolution rate and solubility of SIM.     

Solid molecular dispersions of poorly water-soluble drugs in poly(2-hydroxyethyl methacrylate) hydrogels.

The applicability of cross-linked hydrogels in forming solid molecular dispersions to enhance the delivery of poorly soluble drugs has not been fully explored. The purpose of this study is to characterize physicochemical parameters affecting the formation of solid molecular dispersions of poorly water-soluble drugs in poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels and to investigate the effect of storage humidity levels on their physical stability. Samples were prepared by an equilibrium solvent loading process, using diclofenac sodium, piroxicam and naproxen as model drugs. These were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), as well as changes in the physical state during storage under different humidity conditions. The results show that a threshold drug loading level of about 30% exists in these solid molecular dispersions, above which amorphous to crystalline transition may occur. At any given drug loading, the onset of such change in physical state is accelerated at higher relative humidity levels during storage. The presence of hydrogen bonding between the polymer and the drug, as reflected in the observed FTIR band shifts, improves the compatibility between the drug and the polymer. This, together with a decreased mobility in the glassy polymer, helps to retard the crystallization event below the loading threshold. An increase in dissolution rate is also observed from the polymeric solid molecular dispersion as compared with that of the crystalline pure drug. These physicochemical results indicate that solid molecular dispersions based on PHEMA hydrogels can effectively enhance the dissolution and therefore should be potentially useful in improving the oral bioavailability of poorly water-soluble drugs.     

Solubility enhancement of a poorly water-soluble anti-malarial drug: experimental design and use of a modified multifluid nozzle pilot spray drier

A modified multifluid nozzle spray drier was used to prepare drug containing microparticles of a poorly water-soluble anti-malarial drug, artemisinin (ART) with the aim of improving its solubility. We investigated the spray drying of ART with maltodextrin (MD) via a full factorial experimental design considering the effect of drying temperature, feed ratio (ART:MD), feed flow rate and pressure on the physical properties and solubility of spray-dried ART. Characterization of the ART powder, spray-dried ART microparticles and spray-dried ART-MD were analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and solubility. DSC and XRD studies suggested that the crystallinity of spray-dried particles was decreased with increasing inlet temperatures and flow rate. The particle size of spray-dried ART microparticles was found to be dependent on inlet temperature, flow rate, pressure and feed ratio. The solubility of spray-dried ART particles in composites was markedly increased as compared to commercial ART. A solubility surface-response model was regressed and statistically assessed before elucidating the significant and direct relationships between inlet temperature and feed rate on one hand and solubility on the other. An optimal pressure condition was observed while feed ratio had relatively reduced effect on solubility. The model was also used in an optimization exercise identifying the optimal solubility to be 66.2 +/- 7.17 microg/mL under the calculated spray drying conditions of: inlet temperature = 140 degrees C, feed ratio (ART:MD) = 0.1, feed flow rate = 250 mL h(-1), and pressure = 1.38 bar.     

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.