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PubMed1998

Crystallization of bulk samples of partially amorphous spray-dried lactose.

The crystallization of partially amorphous spray-dried lactose was studied as a function of sample size. Crystallization occurred gradually over a period of 80 hr for a 95-g sample. The water content during crystallization was lower than that needed to cause crystallization if it had been distributed evenly throughout the bed, thus the absorbed water must have been unevenly distributed. The weight of the sample continued to change for days after crystallization was completed, because of the slow desorption of condensed water and the very slow formation of the hydrate form. Surprisingly, all samples with a weight between 42 and 95 g were found to take up the same mass (not percent) of water at the same time. This provides further evidence that the water was not evenly distributed throughout the sample. Water loss after this peak differed in the different weight samples, with the largest weights resulting in the lowest residual weight after 2 weeks. Only the sample of 22 g load had a different peak weight and a much lower weight loss after crystallization. This study provides detail of how partially amorphous bulk samples crystallize.

Calorimetry↗
PubMed2003

Effects of spray-dried animal plasma in calf milk replacer on health and growth of dairy calves.

Male Holstein calves (n = 120) purchased from local dairy farms were fed one of three calf milk replacers for 42 d. Experimental milk replacers were formulated to contain whey protein concentrate (WPC) as the primary protein source or WPC plus 5% spray-dried bovine plasma (SDBP) or spray-dried porcine plasma (SDPP). The SDPP was heated to remove heat-insoluble materials and provide products with similar IgG content. Calves were also fed commercial calf starter and water for ad libitum consumption. Intake, change in body weight (BW), feed efficiency, morbidity and mortality were determined. Mortality was 10, 3, and 2 in calves fed WPC, SDBP, and SDPP treatments, respectively. Morbidity, measured as the number of days that calves had diarrhea was reduced by 30% when SDBP or SDPP were fed. Calves had diarrhea for 6.9, 3.9, and 4.7 d during the 42-d study when fed commercial calf milk replacer containing WPC, SDBP, and SDPP, respectively. Fecal scores tended to be reduced and feed efficiency tended to be improved when SDBP or SDPP were fed. Mean intakes of total dry matter during the 42-d study were greater when calves were fed SDBP or SDPP and were 661, 710, and 684 g/d for calves fed WPC, SDBP, and SDPP, respectively. Mean BW gains from d0 to 42 were 231,261, and 218 g/d, respectively. Calves fed SDPP tended to have lower BW gain during the first 28 d of the study. However, difference in daily BW gain from d 1 to 28 was only 39 g/d. Inclusion of SDBP or SDPP in milk replacer reduced morbidity and mortality of milk-fed dairy calves.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Preparation of spray-dried microspheres of indomethacin and examination of the effects of coating on dissolution rates.

In this study, microspheres were prepared by the spray drying technique using suspensions of indomethacin (IM) as active substance and coated by three different polymers in order to increase the dissolution rate of IM. Water solutions (0.1, 0.2 and 0.5%) of hydroxypropylmethyl cellulose (HPMC), polyvinyl alcohol (PVA) and hydroxypropyl cellulose (HPC) were used as coating materials. Polyethylene glycol 400 (PEG 400) was added to all formulations as plasticizer. Changes of particles size and surface characteristics of the coated products were examined using optical microscopy and scanning electron microscopy (SEM), respectively. The effects of coatings on the dissolution rates of IM were examined using USP XXIII Method II in water and phosphate buffer pH 7.4. It was observed that coating the IM particles with HPMC, PVA and HPC polymers using the Spray-Drying Technique increased the dissolution rate of IM significantly.

Aerosols↗
PubMed1999

The effect of formulation excipients on protein stability and aerosol performance of spray-dried powders of a recombinant humanized anti-IgE monoclonal antibody.

PURPOSE: To study the effect of trehalose, lactose, and mannitol on the biochemical stability and aerosol performance of spray-dried powders of an anti-IgE humanized monoclonal antibody. METHODS: Protein aggregation of spray-dried powders stored at various temperature and relative humidity conditions was assayed by size exclusion chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Protein glycation was determined by isoelectric focusing and affinity chromatography. Crystallization was examined by X-ray powder diffraction. Aerosol performance was assessed as the fine particle fraction (FPF) of the powders blended with coarse carrier lactose, and was determined using a multiple stage liquid impinger. RESULTS: Soluble protein aggregation consisting of non-covalent and disulfide-linked covalent dimers and trimers occurred during storage. Aggregate was minimized by formulation with trehalose at or above a molar ratio in the range of 300: 1 to 500:1 (excipient:protein). However, the powders were excessively cohesive and unsuitable for aerosol administration. Lactose had a similar stabilizing effect, and the powders exhibited acceptable aerosol performance, but protein glycation was observed during storage. The addition of mannitol also reduced aggregation, while maintaining the FPF, but only up to a molar ratio of 200:1. Further increased mannitol resulted in crystallization, which had a detrimental effect on protein stability and aerosol performance. CONCLUSIONS: Protein stability was improved by formulation with carbohydrate. However, a balance must be achieved between the addition of enough stabilizer to improve protein biochemical stability without compromising blended powder aerosol performance.

Aerosols↗
PubMed1997

Evaluation of spray-dried animal plasma and select menhaden fish meal in transition diets of pigs weaned at 12 to 14 days of age and reared in different production systems.

We conducted two experiments with pigs weaned at 12 to 14 d of age to evaluate the effects of adding spray-dried animal plasma (SDAP) and select menhaden fish meal (SMFM) to the diets fed from 5 to 19 (Exp. 1) and 7 to 21 d (Exp. 2) after weaning. This 14-d period represents the transition from the nutrient-dense diet fed to all pigs after weaning to the simpler corn-soybean meal-based diet fed to all pigs for an additional 14 (Exp. 1) or 7 d (Exp. 2) after the experimental period. Pigs averaged 5 kg at the start of the experimental period. In Exp. 1, pigs had a high health status and were weaned to an off-site nursery (SEW) and fed 12 experimental diets in a 3 (0, 2.5, or 5% SDAP) x 4 (0, 2.5, 5, or 7.5% SMFM) factorial arrangement. Diets were formulated to contain 1.6% lysine and contained 20% dried whey, 5% soybean oil, and 2.5% spray-dried blood meal. The SDAP and(or) SMFM replaced corn and soybean meal on an equal lysine basis. Average daily gain and ADFI were not affected by treatment during any period of the experiment. Gain:feed was improved by the addition of SDAP (linear, P < .05) and SMFM (linear, P < .07) during the period from 5 to 19 d. Over the 33-d experiment, SDAP and SMFM improved (linear, P < .05) gain:feed. In Exp. 2, pigs were weaned on-site to an all-in/all-out by room nursery and fed diets identical to those fed in Exp. 1, with 0 or 2.5% SDAP and 0, 2.5, or 5% SMFM in a 2 x 3 factorial arrangement. The addition of 2.5% SDAP improved ADG and gain:feed during the period from 7 to 14 d (P < .05) and 0 to 28 d (P < .10), but not over the period from 7 to 21 d. The addition of SMFM did not affect ADG during any period, but it resulted in a quadratic improvement in gain:feed during the periods from 7 to 14 (P < .05) and 7 to 21 (P < .10) d. These results suggest that high-health SEW pigs respond less to SDAP and SMFM in the transition diet than pigs with a lower health status reared in an on-site nursery. The data further suggest that formulation of transition diets should consider the type of production system if pig performance and diet cost are to be optimized.

Aging↗
PubMed2005

Effects of process variables on the powder yield of spray-dried trehalose on a laboratory spray-dryer.

A systematic examination is presented of the effects of process variables on the powder yield of amorphous trehalose obtained from the Buchi Model 191 laboratory-scale mini spray dryer. By using a specially made, narrow cyclone the powder yield could be greatly improved at all process temperatures examined. Calculations of the separation efficiencies of the improved cyclone and the manufacturer's standard cyclone are given, which show that the former's higher tangential particle velocity at the radius of the exit duct is responsible for the improved performance. The powder yield increases with higher process temperatures, owing to improved droplet drying and reduced droplet/particle deposition on the walls of the drying chamber. A maximum in the powder yield is reached, however, after which it decreases sharply. This is caused by heating of the cyclone wall to >10 degrees C above the so-called 'sticky point' of the trehalose, causing increased particle deposits on the walls of the tower and cyclone. Increasing liquid feed flow rate or decreasing atomizing air flow rate too extensively were both detrimental to powder yield. The drying air flow rate should be as high as possible to ensure sufficient enthalpy throughput to dry the trehalose adequately to give a high powder yield. The enthalpy balance calculation for drying trehalose with the new cyclone was used successfully to interpret the results obtained. Some recommendations for optimizing powder yield of an amorphous material are given.

Powders↗
PubMed2006

Effect of manufacturing parameters on the characteristics of vitamin C encapsulated tripolyphosphate-chitosan microspheres prepared by spray-drying.

To prepare the sustained release vitamin C carriers, vitamin C was successfully encapsulated in tripolyphosphate (TPP) cross-linked chitosan (TPP-chitosan) microspheres by the spray-drying method at different manufacturing conditions. Manufacturing parameters (inlet temperature, liquid flow rate, chitosan concentration and volume of 1% w/v TPP solution) had a significant influence on the characteristics of thus prepared microspheres. The optimum spray-drying conditions such as inlet temperature, liquid flow rate and compressed air flow rate for the encapsulation of vitamin C in TPP-chitosan microspheres was found to be 170 degrees C, 2 ml min(-1) and 101 min(-1), respectively. The size and yield of the TPP-chitosan microspheres ranged from 3.9-7.3 microm and 54.5-67.5%, respectively. The encapsulation efficiency of TPP-chitosan microspheres ranged from 45.72-68.7% and it decreased with the increasing volume of 1% w/v TPP solution. At the same cross-linking extent, the encapsulation efficiency of TPP-chitosan microspheres increased when the concentration of chitosan was increased from 0.5-1% w/v. Effect of volume of 1% w/v TPP solution on the surface morphology of chitosan microspheres was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These studies revealed that chitosan solution (250 ml) cross-linked with 15 ml 1% w/v TPP solution produced more porous microspheres than that cross-linked with 5 and 10 ml TPP solution. The release rate of vitamin C from TPP-chitosan microspheres decreased when the concentration of chitosan was increased from 0.5-1.0% w/v. Vitamin C release rate was also modulated by varying the volume of 1% w/v TPP solution. The release rate of vitamin C from TPP-chitosan microspheres decreased with increasing volume (5-15 ml) of 1% w/v TPP solution.

Ascorbic Acid↗
PubMed2000

Passive immunoglobin transfer in newborn calves fed colostrum or spray-dried serum protein alone or as a supplement to colostrum of varying quality.

Two experiments were conducted to investigate the effect of serum-derived immunoglobin (Ig) source and the effect of colostrum supplementation with serum-derived Ig on the attainment of passive immunity in newborn colostrum-deprived calves. In experiment 1, colostrum-deprived Holstein bull calves were fed pooled colostrum (PC, n = 9), spray-dried bovine serum (BS, n = 11), or spray- dried porcine serum (PS, n = 9). All treatments were balanced to provide 45 g of IgG in a 2-L volume at birth and again 12 h later. Calves receiving BS had higher 24-h serum IgG concentrations than did calves receiving PC or PS (8.3, 5.7, and 4.2 g of IgG/L for BS, PC, and PS, respectively). In experiment 2, the effect of supplementing bovine colostrum of varying quality with BS on Ig absorption was assessed. Thirty-two colostrum-deprived Holstein bull calves and four freemartin heifer calves were allotted by birth order to receive one of three treatments. Treatments consisted of 1) 2 L of pooled high quality colostrum (95.8 g of IgG, 0% from BS), 2) 2 L of pooled medium quality colostrum mixed with BS (95.2 g of IgG, 47% from BS), or 3) 2 L of low quality colostrum mixed with BS (98.8 g of IgG, 70% from BS). Serum IgG concentrations at 24 h after treatment were greater for calves receiving medium and low quality colostrum supplemented with BS (6.2, 9.6, and 9.6 g of IgG/L for high, medium, and low quality colostrum, respectively). Similarly, apparent efficiency of IgG absorption was greater for calves receiving medium and low quality colostrum supplemented with BS (25, 37, and 38% for high, medium, and low quality colostrum, respectively). The results of these studies suggest that dried BS contains a concentrated source of Ig, which is efficiently absorbed by newborn calves. Supplementation of marginal or low quality colostrum with dried BS is an effective means of improving passive transfer of IgG in newborn calves.

Animals↗
PubMedDate not supplied

Solvent influence on spray-dried biodegradable microspheres.

Microspheres of fixed poly(D,L-lactic acid) (PDLLA) composition--Resomer R104:R202H (30:70)--containing 20% w/w rifampicin have been spray-dried from a range of acetonic, halogenated, and solvent mixtures thereof under constant process conditions to examine the influence of solvent selection on microsphere characteristics. Solubility of the polymer composite in the studied solvents determined the kinetics of polymer deposition during drying. Viscosity studies provided an indirect index of solvent power in ascending order: acetone (ACT) < dichloromethane (DCM) < chloroform (CFM) < halothane (HAL). Accordingly, poorer acetonic solvents produced a more open, porous matrix of increased mean diameter, whereas DCM, CFM and HAL generated more coherent matrices of greater density and elevated glass transition temperature, which significantly retarded drug release. Yield generally increased in parallel with solvent strength and microsphere density consistent with the proposed generalized particle formation mechanism. Residual solvent also increased with particle density, both parameters being interrelated and dictated by the inherent affinity of the polymer composite for individual solvents. In turn, the position of glass transition temperature (Tg) and the quantity of associated polymer stress-relaxation were a direct function of amount and persistence of organic residue. The magnitude of these changes determined the relative rates and extents of microsphere ageing, as measured by drug release studies. In general, rate of drug release increased with Tg, after corrections were made for specific surface area (r2 = 0.963). Overall, solvent choice for spray-drying has a remarkable influence on microsphere characteristics and, accordingly, technological as well as toxicological considerations should be paid during selection of same.

Biodegradation, Environmental↗
PubMed2000

Temperature- and moisture-induced crystallization of amorphous lactose in composite particles with sodium alginate prepared by spray-drying.

The purpose of this study was to investigate the temperature- and moisture-induced crystallization of amorphous lactose in the composite particles prepared by spray-drying an aqueous solution of crystalline lactose and sodium alginate. The temperature-induced crystallization of amorphous lactose in the composite particles was suppressed by increasing the amount of sodium alginate in the particles. The stabilizing effect of sodium alginate on amorphous lactose in the composite particles was greater than that in physical mixtures having the same formulating ratios. The improved stability of amorphous lactose in the composite particles was attributed to an increase in the glass transition temperature (Tg) of the mixture. Moisture-induced crystallization of amorphous lactose was also retarded by increasing the amount of sodium alginate in composite particles. Although the Tg of the mixture was reduced by increasing the water content of the particles, the values were higher than that of 100% amorphous lactose when particles of the same water content were compared. The change in the Tg of the composite particles with increasing water content was interpreted as involving three components of the Gordon-Taylor equation. In the amorphous lactose-sodium alginate systems, the Tg values of the composite particles containing sodium alginate were higher than the theoretical line predicted by two components of the Gordon-Taylor equation. These results suggested that there was a specific interaction between the sodium alginate and lactose molecules. This specific interaction was suggested by the fact that only very little amorphous lactose was measured in the spray-dried composite particles stored under humid conditions using differential scanning calorimetry. This molecular interaction may also be partly responsible for the suppression of both the temperature- and moisture-induced crystallization of amorphous lactose in the composite particles.

Alginates↗
PubMed2005

In vivo evaluation of tablets and capsules containing spray-dried o/w-emulsions for oral delivery of poorly soluble drugs.

It is recognised that poorly soluble drugs may show an increased oral bioavailability when incorporated in o/w-emulsions. Encapsulating the emulsion lipid droplets in hydroxypropyl methylcellulose (HPMC) by spray drying has been demonstrated to preserve an improved bioavailability releasing lipid droplets from the powder in vivo. However, the spray-dried powder is cohesive and bulky requiring additional processing to improve handling. This was resolved in previous work where a directly compressible dry emulsion formulation was described. The purpose of the present study is to investigate the oral bioavailability resulting from administration of a directly compressible dry emulsion as a tablet and compare it with a HPMC dry emulsion powder and a simple lipid solution. Four female Beagle dogs received a single dose of each formulation containing the same amount of medium-chain triglycerides (MCT) and a model drug, Lu 28-179. Cyclodextrin solutions administered orally and intravenously were used as references. The absolute bioavailability decreased in the order cyclodextrin solution (0.14), HPMC dry emulsion (0.11), technically improved dry emulsion (0.10) and MCT solution (0.06). The directly compressible dry emulsion tablets were concluded to be comparable to a HPMC dry emulsion powder in terms of bioavailability. The lack of statistically significant differences relative to a MCT solution was ascribed to a low and variable absolute oral bioavailability of the model drug.

Administration, Oral↗
PubMed2004

Utilization of energy and amino acids of spray-dried egg, plasma protein, and soybean meal by ducks.

A study was conducted to determine AMEn, TMEn, apparent amino acid digestibility (AAAD), and true amino acid digestibility (TAAD) of spray-dried egg (SDE), plasma protein (PP), and soybean meal (SBM). AMEn and TMEn values for ducks fed SDE were higher (P < or = 0.001) than for ducks fed PP, which were higher than SBM. The AMEn values were 5.048, 3.230, and 2.605 kcal/g for SDE, PP, and SBM, respectively, with TMEn values of 5.373, 3.555, and 2.930 kcal/g, respectively. Spray-dried egg, PP, and SBM were similar in apparent digestibility of the indispensable amino acids except for methionine, histidine, and valine. Apparent methionine digestibility in SDE (95.5%) was higher (P < or = 0.01) than PP (88.3%) or SBM (91.3%). Apparent digestibilities of dispensable amino acids were similar for SDE, PP, and SBM except proline and alanine. Apparent alanine digestibility in SDE (89.9%) was higher (P < or = 0.05) than in SBM (85.7%). True digestibilities of indispensable amino acids were similar in SDE, PP, and SBM except for methionine, histidine, and valine. True methionine digestibility was higher (P < or = 0.05) for SDE (97.0%) than for PP (89.8%) or SBM (92.7%), with PP and SBM being similar. True histidine and valine digestibilities were significantly lower for SDE (P < or = 0.05) than for PP or SBM. True digestibilities of the dispensable amino acids were also similar in SDE, PP, and SBM except for proline and alanine. This study demonstrates that the energy value of SDE is greater than that of PP or SBM.

Amino Acids↗
PubMed1981

Polymorphism of spray-dried microencapsulated sulfamethoxazole with cellulose acetate phthalate and colloidal silica, montmorillonite, or talc.

Sulfamethoxazole was microencapsulated with cellulose acetate phthalate and talc, colloidal silica, or montmorillonite clay by a spray-drying technique. The surface topography of the products varied with the type of excipient used and the pH of the suspending medium. The products without the excipient were coated with flake-like crusts, while the products containing the excipient tended to become well-rounded spheres. In addition, the crystalline form of sulfamethoxazole converted from Form I to an amorphism and Form II during the spray-drying process. This polymorphic transformation was attributed to the interaction of cellulose acetate phthalate with sulfamethoxazole. Increasing the concentration of cellulose acetate phthalate in the formulation increased the attainment of amorphism. Form II was also obtained by freeze and vacuum drying. Talc was the only excipient that contributed to polymorphism, which occurred in the alkaline suspension medium. Montmorillonite products prepared from the acidic medium exhibited an exothermic differential scanning calorimetry thermogram, which might be interpreted in terms of adsorption of the fused sulfamethoxazole with the internal surface of montmorillonite,

Bentonite↗
PubMed2003

Release characteristics of flavor from spray-dried powder in boiling water and during rice cooking.

The release characteristics of flavor in boiling water and the flavor retention in the rice after cooking were investigated by using spray dried powder in encapsulated in or emulsified with d-limonene or ethyl n-hexanoate in cyclodextrin and maltodextrin, or in gum arabic and maltodextrin. The behavior of flavor release into the boiling water was well simulated by Avrami's equation. The retention of d-limonene and ethyl n-hexanoate in cooked rice was correlated in each case with the flavor amount of spray-dried powder added.

Caproates↗
PubMed2002

Formulation factors in preparing BTM-chitosan microspheres by spray drying method.

Chitosan (CTS) microspheres were prepared by a spray drying method using type-A gelatin and ethylene oxide-propylene oxide block copolymer as modifiers. Surface morphological characteristics and surface charges of prepared microspheres were investigated by using scanning electron microscopy (SEM) and microelectrophoresis. The particle shape, size and surface morphology of microspheres were significantly affected by the concentration of gelatin. Betamethasone disodium phosphate (BTM)-loaded microspheres demonstrated good drug stability (less 1% hydrolysis product), high entrapped efficiency (95%) and positive surface charge (37.5 mV). The in vitro drug release from the microspheres was related to gelatin content. Microspheres containing gelatin/CTS 0.4 approximately 0.6(w/w) had a prolong release pattern for 12 h. These formulation factors were correlated to particulate characteristics for optimizing BTM microspheres in pulmonary delivery.

Anti-Inflammatory Agents↗
PubMedDate not supplied

The characteristics of betamethasone-loaded chitosan microparticles by spray-drying method.

Betamethasone (BTM)-loaded microparticles prepared by a spray drying method using chitosan (CTS) as raw material, type-A gelatin and ethylene oxide-propylene oxide block copolymer (Pluronic F68) as modifiers. The BTM-loaded in varied chitosan/Pluronic F68/gelatin microparticle formulations was investigated. By properly choosing excipient type and concentration a high degree of control was achieved over the physical properties of the BTM-loaded microparticles. Microparticle characteristics (zeta potential, tap density, particle size and yield), loading efficiencies, microparticle morphology and in-vitro release properties were examined. Surface morphological characteristics and surface charges of prepared microparticles were observed by using scanning electron microscopy (SEM) and microelectrophoresis. A SEM micrograph shows that the particle sizes of the varied chitosan composed microparticles ranged from 1.1-4.7 microm and the external surfaces appear smooth. The BTM-loaded microparticles entrapped in the chitosan/Pluronic F68/gelatin microparticles with trapping efficiencies up to 93%, collected yield rate 44%, and mean particle size varied between 1-3 microm, positive surface charge (20-40 mv), and tap densities (0.04-0.40 g/cm3) were obtained. The collected BTM yield and size of particle was increased with increasing BTM-loaded amount but both zeta potential and tap density of the particles decreased with increasing BTM-loaded amount. The in vitro release of BTM showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the concentration range between 5-30%w/w. The in vitro drug release from the chitosan/Pluronic F68/gelatin 1/0.1/0.4 microspheres had a prolong release pattern. These formulation factors were correlated to particulate characteristics for optimizing BTM microspheres in pulmonary delivery.

Anti-Inflammatory Agents↗
PubMedDate not supplied

Effects of fabrication conditions on the characteristics of etanidazole spray-dried microspheres.

Etanidazole, a hypoxic radiosensitizer, has potential applications in radiotherapy. Due to its high solubility in water, common methods to encapsulate etanidazole into microspheres are not feasible. In this study, a spray-drying technique was employed to encapsulate etanidazole into the biodegradable polymer, PLGA65:35. Different fabrication conditions, such as polymer concentration, inlet temperature, feed rate, compressed air flow rate, aspirator ratio, as well as drug-loading were investigated to understand their effects on the particle size and distribution, encapsulation efficiency, and release behaviour. The effect on the morphologies of microspheres were also observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was demonstrated that most of these fabrication conditions influence either the droplet formation process or its subsequent evaporation and particle shrinking process, thereby determining the properties of the microspheres obtained. In many cases, temperature seems to be more important among all the factors considered. The present study demonstrates good fabrication conditions for producing the etanidazole-PLGA65:35-microspheres by using DCM as a solvent. The release of etanidazole from the spray dried PLGA65:35 microspheres was very fast, with an initial burst of 47% within the first 30 min and a cumulative release of over 80% within the first 5.5 h. The encapsulation efficiency of the drug in the microspheres varied with operating conditions from 69-96%.

Calorimetry, Differential Scanning↗
PubMed2003

Effect of polymer content and molecular weight on the morphology and heat- and moisture-induced transformations of spray-dried composite particles of amorphous lactose and poly(vinylpyrrolidone).

PURPOSE: The aim was to investigate the influence of polymer content and molecular weight on the morphology and heat- and moisture-induced transformations, as indicators of stability, of spray-dried composite particles of amorphous lactose and poly(vinylpyrrolidone) (PVP). METHODS: Amorphous lactose and composite particles of amorphous lactose with different contents and molecular weights of PVP were prepared by spray drying. The nanostructure of the particles was analyzed by x-ray powder diffractometry, the morphology by light microscopy and SEM, the glass transition temperatures (Tg), crystallization temperatures (Tc), heats of crystallization and melting temperatures by differential scanning calorimetry, and moisture-induced crystallizations gravimetrically and by microcalorimetry. RESULTS: All the types of particles prepared were amorphous. The Tg was unchanged or only marginally increased as a result of the inclusion of PVP. However, crystallization temperature, time to moisture-induced crystallization, and particle morphology were affected by both content and molecular weight of PVP. CONCLUSIONS: Increased content and molecular weight of PVP may have the potential to increase the physical stability of amorphous lactose. However, Tg seems not to be a relevant indicator for the stability of this type of amorphous composite materials.

Drug Stability↗