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PubMedDate not supplied

Microencapsulation of erythromycin and clarithromycin using a spray-drying technique.

Previous methods of microencapsulation are unable to process particles smaller than 100 microm without organic solvents or the use of multistep processes. The present study investigates the feasiblity of a one-step spray-drying process to microencapsulate erythromycin and clarithromycin, antibiotics known to have an unpleasant, bitter taste. Mixtures of clarithromycin (5% by weight) or erythromycin (30% by weight) with a biodegradable polymer were prepared and spray-dried under specific conditions of temperature and turbine speed. This process resulted in the microencapsulation of 80% of each drug as determined by high pressure liquid chromatography. Particle size ranged from 1 to 80 microm as determined by electron microscopy. These data show that microencapsulation of macrolides using a spray-drying technique is feasible. Spray-drying microencapsulation might be useful in the formulation of palatable oral suspensions of bitter tasting drugs.

Anti-Bacterial Agents↗
PubMed2005

Intrinsic tolerance of Bifidobacterium species to heat and oxygen and survival following spray drying and storage.

AIMS: This study examined the tolerance of various species of the genus Bifidobacterium to heat and oxygen and evaluated the survival of selected strains following spray drying and during storage. METHODS AND RESULTS: Nine Bifidobacterium species were considered to be relatively tolerant to both heat and oxygen and mostly segregated into two clusters within the 16S rDNA phylogenetic tree. Four species were tolerant to oxygen and 12 species were considered sensitive to oxygen and heat. Using a skimmed milk-based carrier good survival following spray drying and storage at 4 degrees C correlated with tolerance to heat and oxygen. Viability was inversely related to storage temperature and at 15 degrees C and 25 degrees C, a significant decline was observed for all species. The inclusion of gum acacia had no significant affect on survival or viability. However, using a fluidized-bed spray dryer viability was greatly improved. CONCLUSIONS: A group of closely related species tolerant to heat and oxygen had high survival following spray drying and maintained viability during prolonged storage at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: Spray drying is a suitable method for the production of skimmed milk powder enriched with high numbers of viable bifidobacteria.

Bifidobacterium↗
PubMed2004

Liposomes and disaccharides as carriers in spray-dried powder formulations of superoxide dismutase.

In this study, we aim to investigate the effects of disaccharides and liposome carriers on the activity, solid state characteristics, structural preservation, and aerosol powder performance of spray-dried superoxide dismutase (SOD) formulations. Sucrose, trehalose, and lactose were selected as stabilizing adjuvants in the spray-drying process. Dipalmitoyl phosphatidylcholine (DPPC) was the major lipid component for preparing liposomes. These SOD formulations were characterized with SOD activity assay, particle size, residual moisture content, scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), differential scanning calorimeter (DSC), and Fourier transform infrared (FT-IR) spectroscopy. We found that the inlet/outlet temperature of spray drying can be performed up to 168/122 degrees C with maintaining the activity of SOD in the SOD\DPPC\sucrose formulation for 98%. The SEM image of this formulation showed wrinkled and raisin-like appearance. Aerosol powder performance test demonstrated that this formulation exhibited excellent emitted dose (ED, 71%), aerodynamic diameter (2 microm), and respirable fraction (RF, 72%). DSC study suggested an indication of initial electrostatic stabilization of SOD by DPPC and sucrose, the following lipid perturbation by SOD, and the formation of an inclusion complex, thus minimizing the individual transition peaks of SOD and DPPC. FT-IR study showed that the major secondary structure of SOD, beta-sheet, was maintained in this formulation. The surface ESCA analysis of this formulation suggested the absence of SOD on the surface region of the powders, indicating that SOD was well surrounded and protected by DPPC and sucrose. Spray drying has been demonstrated to be a feasible process to preserve the activity of SOD in the formulation of DPPC liposomes with sucrose.

Animals↗
PubMed2001

Spray-dried insulin particles retain biological activity in rapid in-vitro assay.

The purpose of this study was to rapidly determine, without the use of extensive animal studies, whether biological activity is retained after spray drying insulin with two excipients, lactose and xanthan gum. This was achieved by the detection of protein kinase B (PKB), which is activated by phosphorylation in response to insulin binding to cellular receptors. A myeloid cell line was cultured and stimulated with the reconstituted insulin powders. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was then utilised to allow in-vitro detection of phosphorylated PKB using an anti-phospho-PKB antibody. A single band specific to phosphorylated PKB was found on the Western blots, indicating that the active conformation of insulin was retained when spray dried in combination with lactose and with xanthan gum over the spray-drying inlet temperature range of 110-170 degrees C. Evidence of inactivation/denaturation was observed when insulin was spray dried at an inlet temperature of 200 degrees C. The assay may be of use as a more rapid and economic means to screen insulin formulations for inhalation and other purposes as opposed to conventional monitoring of blood glucose levels in animals.

Desiccation↗
PubMed2003

Physicochemical evaluation of carbamazepine microparticles produced by the rapid expansion of supercritical solutions and by spray-drying.

PURPOSE: To compare the physical and physicochemical characteristics of carbamazepine microparticles prepared using two different methods: (1) the rapid expansion of supercritical solutions (RESS) and (2) the spray-drying process. METHODS: For both processes, microparticles were produced over a range of different temperatures (35 to 100 degrees C). For the RESS method, carbon dioxide was the solvent used over a pressure range of 2500 to 3500 psi. As for the spray-drying method, different organic solvents were used at atmospheric pressure. Comparison was based on morphology, crystalline structure, mean particle size, and size distribution of processed particles. The influence of process parameters on microparticles' characteristics was also investigated. Particles were analyzed using scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), thermogravimetric analyzer (TGA), and differential scanning calorimetry (DSC). RESULTS: The carbamazepine particles used as unprocessed starting material had a mean diameter of approximately 85 microm with a size distribution range between 15 and 336 microm. Microparticles produced by either the RESS or spray-drying method had a mean diameter smaller than 2 microm and a narrower size distribution range between 0.25 and 2.5 microm. SEM photomicrographs, X-ray diffractograms, and DSC spectra revealed that modification of crystal morphology was dependent on the operating conditions. CONCLUSIONS: Significant reduction in mean particle size and size distribution range of carbamazepine particles was observed by RESS and spray-drying methods. The results also demonstrate that the crystalline nature of carbamazepine particles depends on the method of production and on the operating parameters of pressure and temperature.

Carbamazepine↗
PubMedDate not supplied

Influence of various technological parameters on the preparation of spray-dried poly(epsilon-caprolactone) microparticles containing a model antigen.

This work evaluates the efficacy of the spray-drying technique to prepare poly(epsilon-caprolactone) (PCL) microparticles containing an entrapped model antigen (bovine albumin, BSA). The presence of a stabiliser was found to be an important parameter when preparing PCL microparticles containing a hydrophilic antigen. The effect of various technological parameters (concentration of the polymer and protein solutions, organic/aqueous phases ratio, nature of solvents and emulsion parameters such as duration and speed of agitation) on microparticle morphology and size, BSA entrapment and encapsulation efficiency was studied. Microparticles were characterized by a mean size from 9.56+/-0.25 to 24.31+/-2.87 microm and a BSA entrapment from 0.80+/-0.02 to 24.21+/-0.23% (w/w). SDS-PAGE electrophoresis and isoelectric focusing (IEF) confirmed the conservation of the physicochemical characteristics of the BSA entrapped within PCL microparticles produced by spray-drying. Together, these results showed that spray-drying is an efficient technique to overcome the key obstacle that represents the scaling-up of the manufacturing process to produce sufficient quantities of vaccine for clinical trials and, ultimately, commercialization.

Animals↗
PubMed2005

Spray-dried Bacillus thuringiensis Serovar israelensis formulations for control of Aedes aegypti larvae.

Suspensions containing 0.25 and 1.25 g/liter of Bacillus thuringiensis subsp. israelensis (Bti) spore-toxin complex were spray-dried by using maltodextrin DE-6, corn starch, and nixtamalized corn flour (25 g/liter) as materials to entrap active delta-endotoxin. The inlet air temperature of the drier was kept constant at 141 degrees C and the outlet temperature was maintained at 60 or 70 degrees C. The Probit analysis of the concentration-mortality response of third instars of Aedes aegypti (L.) larvae of the spray-dried products at 60 degrees C showed that LC50 values for maltodextrin DE-6 with 1 and 5% spore-toxin complex were 4 and 10% higher in toxicity, respectively, than that for the unformulated spore-toxin complex without drying. The LC50 value for corn starch with 1 and 5% of spore-toxin complex were also higher in toxicity (7 and 8% respectively). However, LC50 values for nixtamalized corn flour with one and 5% spore-toxin complex were 81 and 55% higher in toxicity, respectively. Dried products contain an a(w) < or = 0.7, suggesting that they are able to keep the products without microorganism growth for longer periods. The scanning electron microscope of Bti spray-dried formulations with nixtamalized corn flour showed smooth spherical particles entrapping the active ingredient. These results suggested that Bti spore-toxin complex formulated with maltodextrin DE-6, corn flour, and nixtamalized corn flour, and then spray-dried may increase larval feeding and thus increase activity against Ae. aegypti larvae.

Aedes↗
PubMed2005

The use of amino acids to enhance the aerosolisation of spray-dried powders for pulmonary gene therapy.

BACKGROUND: Pulmonary delivery of gene therapy offers the potential for the treatment of a range of lung conditions, including cystic fibrosis, asthma and lung cancer. Spray-drying may be used to prepare dry powders for inhalation; however, aerosolisation of such powders is limited, resulting in poor lung deposition and biological functionality. In this study, we examine the use of amino acids (arginine, aspartic acid, threonine, phenylalanine) to enhance the aerosolisation of spray-dried powders containing model non-viral gene vectors. METHODS: Lipid/polycation/pDNA (LPD) vectors, in the presence or absence of amino acids, were dispersed in lactose solutions, and spray-dried to produce appropriately sized dry powders. Scanning electron microscopy and laser diffraction were used to determine particle morphology and diameter, respectively. Gel electrophoresis was used to examine the influence of amino acids on the structural integrity of the LPD complex. In vitro cell (A549) transfection was used to determine the biological functionality of the dry powders, and the in vitro aerosolisation performance was assessed using a multistage liquid impinger (MSLI). RESULTS: Both gel electrophoresis and in vitro cell transfection indicated that certain amino acids (aspartic acid, threonine) can adversely affect the integrity and biological functionality of the LPD complex. All amino acids significantly increased the aerosolisation of the powder, with the arginine and phenylalanine powders showing optimal deposition in the lower stages of the MSLI. CONCLUSIONS: Amino acids can be used to enhance the aerosolisation of spray-dried powders for respiratory gene delivery, allowing the development of stable and viable formulations for pulmonary gene therapy.

Administration, Inhalation↗
PubMed2006

Evaluation of anxiolytic activity of spray dried powders of two South Brazilian Passiflora species.

The Passiflora extracts have been used in folk medicine because of its reputed sedative and anxiolytic properties. The present study aimed to compare the potential anxiolytic activity of two Passiflora spray-dried powders obtained from P. alata and P. edulis, known in Brazil as 'maracujá'. Male adult Swiss rats were treated with 200, 400 and 800 mg/kg of spray-dried powders p.o. and anxiolytic activity was evaluated using the elevated plus-maze test. The spray-dried powders showed anxiolytic activity in doses of 400 and 800 mg/kg. Our results support the potential anxiolytic effect of Passiflora spray-dried powders (P. alata and P. edulis).

Administration, Oral↗
PubMed2005

The use of absorption enhancers to enhance the dispersibility of spray-dried powders for pulmonary gene therapy.

BACKGROUND: Pulmonary gene therapy requires aerosolisation of the gene vectors to the target region of the lower respiratory tract. Pulmonary absorption enhancers have been shown to improve the penetration of pharmaceutically active ingredients in the airway. In this study, we investigate whether certain absorption enhancers may also enhance the aerosolisation properties of spray-dried powders containing non-viral gene vectors. METHODS: Spray-drying was used to prepare potentially respirable trehalose-based dry powders containing lipid-polycation-pDNA (LPD) vectors and absorption enhancers. Powder morphology and particle size were characterised using scanning electron microscopy and laser diffraction, respectively, with gel electrophoresis used to assess the structural integrity of the pDNA. The biological functionality of the powders was quantified using in vitro cell (A549) transfection. Aerosolisation from a Spinhaler dry powder inhaler into a multistage liquid impinger (MSLI) was used to assess the in vitro dispersibility and deposition of the powders. RESULTS: Spray-dried powder containing dimethyl-beta-cyclodextrin (DMC) demonstrated substantially altered particle morphology and an optimal particle size distribution for pulmonary delivery. The inclusion of DMC did not adversely affect the structural integrity of the LPD complex and the powder displayed significantly greater transfection efficiency as compared to unmodified powder. All absorption enhancers proffered enhanced powder deposition characteristics, with the DMC-modified powder facilitating high deposition in the lower stages of the MSLI. CONCLUSIONS: Incorporation of absorption enhancers into non-viral gene therapy formulations prior to spray-drying can significantly enhance the aerosolisation properties of the resultant powder and increase biological functionality at the site of deposition in an in vitro model.

Absorption↗
PubMed1999

Compaction properties of composite particles consisting of lactose with sodium alginate prepared by spray-drying.

PURPOSE: Composite particles of lactose with a small amount of sodium alginate were prepared by spray-drying (SD) in an effort to improve the compactibility of the polymer for direct compression. The compaction behavior of the SD composite particles with a range of polymer contents was investigated. METHODS: Composite particles were prepared by spray-drying an aqueous solution of lactose and sodium alginate at various formulating ratios. Improvement in the compactibility of the composite particles was evaluated by measuring the tablet tensile strength, porosity-applied pressure profiles, stress relaxation, elastic recovery of the compressed powder, and surface properties of the tablets by scanning electron microscopy. RESULTS: The tensile strength of compacts formed from the SD composite particles containing sodium alginate (< or = 10 wt%) was as high as that of spray-dried amorphous lactose. The improved compaction was attributed to the higher relaxation pressure and lower elastic recovery of the composite particles compared with alpha-lactose monohydrate. However, increasing the sodium alginate content of the SD composite particles above 10 wt% led to a marked reduction in the tensile strength of the resultant tablets. Scanning electron micrographs revealed that composite particles with a good compactibility fused totally in the tablets while composite particles containing 15% or more sodium alginate retained their shape, even after compression. The presence of sodium alginate layered uniformly on the surface of the particles and the increase in the glass transition temperature of the particles, possibly due to interpolation of sodium alginate are responsible for the reduction in the fusion property of the composite particles on compression. CONCLUSIONS: Although increasing the sodium alginate content of SD composite particles led to an increase in their plastic deformation, fusion on compression was prevented by the presence of sodium alginate. The reduced compactibility of SD composite particles with an excess amount of sodium alginate was attributed to reduced cohesion and fusion of the particles during compression.

Alginates↗
PubMedDate not supplied

Spray-dried microspheres containing ketoprofen formulated into capsules and tablets.

In this study, microspheres were prepared by a spray-drying technique using solutions of ketoprofen and two polymers, cellulose acetate butyrate (CAB) and hydroypropylmethylcellulose phthalate (HPMCP), in different weight ratios. Different total concentrations were used in the feed solutions: 3, 6 and 9% w/v. The spray-dried microparticles were characterized in terms of shape (SEM), size (light scattering method), production yield and encapsulation efficiency. They were formulated into capsules; tablets were prepared by direct compression of the microparticles mixed with maltose and, in some cases, hydroypropylmethylcellulose (HPMC). In vitro release studies were performed both at acidic and neutral pHs. The spray-drying process of solutions of ketoprofen with polymeric blends of cellulose derivatives leads to microparticles which, depending on their final formulation (capsules or tablets), can give a rapid or prolonged drug release. The formulations here described can be proposed for the oral administration of NSAIDs.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Activity-stability considerations of trypsinogen during spray drying: effects of sucrose.

The preparation and processing of protein pharmaceuticals into powders may impose significant stresses that could perturb and ultimately denature them. In many cases their stabilization through added excipients is necessary to yield native and active proteins. In this study, the effect of spray drying on the structure and activity of a model protein (trypsinogen) was investigated. In the absence of excipients, spray drying resulted in small losses of its enzymatic activity. Protein conformational rearrangements in the solid state (observed via FTIR) and irreversible aggregation (upon reconstitution) constituted the major degradation pathways. The irreversible unfolding in the solid state was also confirmed by solution calorimetric studies that indicated a decreased thermal stability of the spray-dried protein after reconstitution. The presence of sucrose, a thermal and dehydration stress stabilizer, induced a concentration-dependent protective effect. Protein protection was afforded even at low carbohydrate concentrations, while at specific mass ratios (sucrose-to-protein = 1:1) complete activity preservation was achieved. However, at the high end of sucrose concentrations, a small destabilization was evident, indicating that excluded volume effects may be undesirable during preparation of protein microparticles via spray drying. The profile of both the protein conformational changes and thermal stability in the solid state closely followed that of the incurred activity losses, indicating that protein stabilization during dehydration is crucial during processing of these polypeptides.

Chemistry, Pharmaceutical↗
PubMed2002

Response of early-weaned pigs to spray-dried porcine or animal plasma-based diets supplemented with egg-yolk antibodies against enterotoxigenic Escherichia colil.

Two experiments involving 168 10-d-old weaned pigs were conducted to compare growth-promoting properties of dietary spray-dried animal plasma (SDAP), spray-dried porcine plasma (SDPP), and chicken egg-yolk antibodies (EYA) or egg-yolk powder (EYP, contains no specific antibodies) from d 0 to 14 postweaning. In Exp. 1, 96 pigs (3.2 +/- 0.2 kg BW) were used to test the hypothesis that the superior performance of piglets fed SDPP-based diets was partly due to the presence of specific antibodies against enterotoxigenic Escherichia coli (ETEC), which could be replaced with EYA. Four experimental diets in a completely randomized design and arranged in a 2 x 2 factorial (SDPP without or with autoclaving [AuSDPP] and without [EYP] or with supplementation of EYA) were used. Autoclaving SDPP at 121degrees C for 15 min completely destroyed anti-K88/F18 antibodies. Overall feed intake and gain:feed ratio were similar (P > 0.05) among treatments and averaged 122.7 g/d and 0.688, respectively. However, pigs fed AuSDPP+EYP diets had poorer (P < 0.001) ADG compared with those fed SDPP+EYP or SDPP+EYA from 0 to 14 d. Scours were four times higher (P < 0.05) for treatment AuSDPP+EYP compared with all other treatments. Plasma urea nitrogen concentration was higher (P < 0.05) in AuSDPP+EYP- and AuSDPP+EYA-fed pigs. Also twice the number of piglets fed AuSDPP+EYP appeared unhealthy compared with piglets on treatment AuSDPP+EYA. In Exp. 2, 72 10-d-old weaned pigs (3.5 kg BW) were used to compare the effect of EYA supplementation and oral challenge of ETEC strain F18 on performance and visceral organ weights. The experimental diets consisted of SDAP+EYP, SDAP+EYA, SDPP+EYP, and SDPP+EYA. From d 0 to 7, and the entire experimental period, dietary treatment did not influence (P > 0.05) growth rate and feed consumption. Plasma urea N concentration was higher (P < 0.05) in piglets fed the SDAP+EYP diet before and after the oral challenge. Gain:feed ratio, organ weights, villi heights, and crypt depths were not affected (P > 0.05) by dietary treatments. The results indicate that SDPP contains specific anti-ETEC antibodies, which is one of the factors responsible for its superior growth-enhancing effects. Spray-dried animal plasma, SDPP and EYA have similar growth promoting effect in early-weaned pigs.

Animal Feed↗
PubMed2004

Beauveria brongniartii subjected to spray-drying in a composite carrier matrix system.

The negative aspects of chemical pesticides are of growing concern to the public. Thus, there is a strong effort to exploit environmentally friendly possibilities for pest management. One strategy is the application of biocontrol agents such as the fungus Beauveria brongniartii. In this context, the central objective of the research presently described is to investigate spray drying as a preservation method for fungal conidia to obtain a practical formulation for spray application. An aqueous binary mixture composed of skim milk (SM) and polyvinylpyrrolidone (PVP K90) was examined as encapsulation matrix. The influence of different inlet/outlet temperature adjustments, the composition of the carrier system and the conidia concentration were examined with respect to their influence on spore viability. Results indicate that air outlet temperatures up to 53 +/- 2 degrees C resulted in a slight reduction of conidial viability (approximately 3%). Microencapsulated conidia have been subjected to storage tests with and without the addition of silica gel capsules at various temperatures. Results show that survival is inversely related to storage temperatures and residual moisture levels of the spray dried powders. The highest survival rates were observed at moisture contents of 3% and a temperature of 10 degrees C. Moreover, production characteristics like entrapment efficacy, shape and size were investigated. Furthermore, the composition of the carrier matrix was optimised to result in production yields of 25%. Results show that spray drying is a useful, economic encapsulation technology for aerial conidia of Beauveria brongniartii resulting in highly concentrated, spray dried powders of 92% viability.

Animals↗
PubMed1998

Characterization of amorphous ursodeoxycholic acid prepared by spray-drying.

The objectives of this study were to characterize the amorphous state of ursodeoxycholic acid (UDCA) samples prepared by spray-drying, and to demonstrate the applicability of thermal and water-vapour-adsorption techniques for studying the material. Amorphous UDCA was prepared by spray-drying a solution of the compound in a mixture of ethanol and dichloromethane. The amorphous material was characterized by powder X-ray diffraction, infrared (IR) spectroscopy, isothermal microcalorimetry, differential scanning calorimetry (DSC) and water-vapour adsorption. When the inlet-air temperature of the spray drier was increased beyond 140 degrees C, the intensity of X-ray diffraction peaks from crystalline UDCA decreased and the IR bands in the hydroxyl-stretching and carboxyl-stretching regions changed. Dissolution of intact and spray-dried samples of UDCA prepared at 60 and 100 degrees C was an endothermic process but the dissolution became exothermic with increasing inlet-air temperature. UDCA samples differing in crystallinity were obtained, depending on the inlet-air temperature. A good correlation was obtained between the heat of solution and the heat of crystallization determined from DSC peak area. A good correlation was also obtained between the heat of solution and the crystallinity determined by Ruland's method from X-ray diffraction patterns. The amount of water vapour adsorbed on UDCA samples increased with increasing inlet-air temperature, indicating hydrogen bonding between water molecules and the hydroxyl groups or the carboxyl groups of amorphous UDCA. These results indicate that measurement of adsorption of water vapour and thermal analysis can both be used to evaluate the crystallinity of solid substances.

Adsorption↗
PubMed2005

Spray-dried amorphous solid dispersions of simvastatin, a low tg drug: in vitro and in vivo evaluations.

PURPOSE: To obtain free flowing, stable, amorphous solid dispersions (SDs) of simvastatin (SIM), a drug with relatively lower glass transition temperature (T(g)) by spray drying technique, and to perform comparative in vivo study in rats, which could justify the improvement in rate and extent of in vitro drug release. METHODS: Dichloromethane suspensions of SIM either alone or in combination with PVP (1:1 or 1:2 parts by weight) were spray dried with proposed quantity of Aerosil 200 (1:1, 1:1:1, 1:2:2 parts by weight of SIM, Aerosil 200 and PVP, respectively). SDs were characterized initially in comparison with pure drug and corresponding physical mixtures in same ratios by drug content, saturation solubility, SEM, DSC, XRPD, IR, and in vitro drug release. SD 1:2:2 was further subjected to accelerated stability testing and checked for in vitro drug release and presence of crystallinity using DSC and XRPD. In addition, improvement in rate and extent of in vitro drug release from SD 1:2:2 was justified by in vivo study in rats. RESULTS: Combination of SD and surface adsorption techniques has been attempted to overcome the limitations of spray drying technique for amorphization of low T(g) drugs. Based on powder characteristics, drug content, saturation solubility, and feasibility of processing into tablets; SD 1:2:2 was selected as the optimized formulation. During initial characterization, SEM, DSC, and XRPD analyses confirmed the presence of amorphous form in SD 1:2:2. IR spectroscopy revealed possibility of hydrogen bonding interaction between SIM and PVP in SDs. Also, there was dramatical improvement in rate and extent of in vitro drug release of SD 1:2:2. Insignificant decrease in dissolution was observed with no evidence of crystallinity during accelerated stability studies of SD 1:2:2. Moreover in vivo study in rats also justified the improvement in therapeutic efficacy of SD 1:2:2 over pure SIM. CONCLUSIONS: Thus, present study demonstrates high potential of spray drying technique for obtaining stable amorphous SDs of low T(g) drugs.

Animals↗
PubMed2006

Spray-dried mucoadhesive microspheres: preparation and transport through nasal cell monolayer.

The purpose of this research was to prepare spray-dried mucoadhesive microspheres for nasal delivery. Microspheres composed of hydroxypropyl methylcellulose (H), chitosan (CS), carbopol 934P (CP) and various combinations of these mucoadhesive polymers, and maltodextrin (M), colloidal silicon dioxide (A), and propylene glycol (P) as filler and shaper, were prepared by spray-drying technique. Using propranolol HCl as a model drug, microspheres were prepared at loadings exceeding 80% and yields between 24% and 74%. Bulky, free flowing microspheres that had median particle size between 15 and 23 mum were obtained. Their zeta potential was according to the charge of polymer. Adhesion time of mucoadhesive microspheres on isolated pig intestine was ranked, CS > CP:H > CP > H, while the rank order of swelling was CP > CS > H. Increasing the amount of CP in CP:H formulations increased the percentage of swelling. Infrared (IR) spectra showed no interaction between excipients used except CS with acetic acid. The release of drug from CP and CP:H microspheres was slower than the release from H and CS microspheres, correlated to their viscosity and swelling. Long lag time from the CP microspheres could be shortened when combined with H. The permeation of drug through nasal cell monolayer corresponded to their release profiles. These microspheres affected the integrity of tight junctions, relative to their swelling and charge of polymer. Cell viability was not affected except from CS microspheres, but recovery could be obtained. In conclusion, spray-dried microspheres of H, CS, CP, and CP:H could be prepared to deliver drug through nasal cell monolayer via the opening of tight junction without cell damaging.

Acrylates↗