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PubMed1995

The effect of dietary methionine and its relationship to lysine on growth performance of the segregated early-weaned pig.

Two experiments were conducted to determine the dietary methionine requirement and the appropriate methionine:lysine for the segregated early weaned-weaned pig. In Exp. 1, 435 crossbred pigs (9.5 +/- 4 d of age and 3.5 kg BW) were fed diets (1.8% lysine, .62% cystine) containing 10% spray-dried plasma protein (SDPP) and 1.75% spray-dried blood meal (SDBM) from day 0 to 21 postweaning. Pigs were feed one of six dietary treatments from .36% to .56% total dietary methionine (.317 to .517% apparent digestible methionine). From d 0 to 7 and d 0 to 21 postweaning, ADG and gain:feed ratio (G/F) increased (linear, P < .01, P < .05, respectively) as dietary methionine increased. In Exp. 2, 350 crossbred pigs (9.0 +/- 2 d of age and 3.8 kg BW) were used to determine the appropriate methionine:lysine ratio for the segregated early-weaned pig in a 2 x 5 factorial arrangement. Two lysine levels (1.8 and 1.4%) and five methionine levels within each lysine level were used to obtain methionine:lysine ratios ranging from 21.5 to 33.5%. From d 0 to 21 postweaning, pigs were assigned to one of 10 dietary treatments containing 25% dried whey, 12% lactose, 7.5% SDPP, 6.0% select menhaden fish meal, and 1.75% SDBM. No methionine x lysine interactions were observed (P > .10). From d 0 to 7 postweaning, increasing dietary methionine improved (quadratic, P < .01) ADG and ADFI regardless of dietary lysine. From d 0 to 14 postweaning, increasing dietary methionine improved ADG (quadratic, P < .01), ADFI quadratic, P =.02), and G/F (quadratic, P < .10). Inflection point analysis projected maximum ADG at methionine:lysine ratios of 27 and 27.5% for pigs fed 1.4 and 1.8% lysine, respectively. Cumulative (d 0 to 21 postweaning) ADG, ADFI, and G/F were improved (quadratic, P < .05) by increasing dietary methionine. Increasing dietary lysine improved (P < .01) ADG and G/F from d 0 to 7, from d 0 to 14, and for the overall experiment. In conclusion, a diet with 1.8% total lysine that includes spray-dried blood products must contain .48 to .52% total dietary methionine (.437 to .477% apparent digestible) or 27.5% of total lysine to maximize growth performance of pigs from d 0 to 21 postweaning (3.5 to 12 kg BW).

Aging↗
PubMed1992

Application of curdlan to controlled drug delivery. I. The preparation and evaluation of theophylline-containing curdlan tablets.

To study the use of curdlan, a natural beta-1,3-glucan, in drug delivery, in vitro release studies were carried out with curdlan tablets containing theophylline. Tablets were readily prepared by compressing three different curdlan and theophylline mixtures, namely, a physical mixture, spray-dried curdlan particles with theophylline powder, and spray-dried particles of curdlan/theophylline solution. Drug release from the tablets prepared from spray-dried particles of curdlan/theophylline was lowest. The release rate was constant from 1 to 8 hr, and 59% cumulative release was obtained at 8 hr. Drug release from curdlan tablets was unaffected by pH or various ions; these curdlan tablets might also control drug release in vivo after oral administration. Application of Higuchi's equation indicated that drug release from curdlan tablets was diffusion-controlled. The release profiles of the curdlan tablets were compared to those of a commercial theophylline sustained-release tablet.

Chemistry, Pharmaceutical↗
PubMed2005

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.

Calorimetry, Differential Scanning↗
PubMed2005

Effect of milling and compression on the solid-state Maillard reaction.

The effects of milling and compression on the solid-state Maillard reaction between metoclopramide hydrochloride and lactose were investigated. Anhydrous metoclopramide hydrochloride was milled for various times, and then mixed with amorphous lactose. The mixtures were stored at 105 degrees C and 0% RH. The reactivity of metoclopramide hydrochloride towards the Maillard reaction increased with milling time, as the result of increased surface area, formation of amorphous content, and creation of defects. Metoclopramide hydrochloride anhydrate and lactose were mixed and the mixtures were compressed into tablets under pressure varied from 70 to 350 MPa. Both tablets and mixtures were stored at 105 degrees C and 0% RH for 9 days. For all three types of lactose used, spray-dried anhydrous lactose, spray-dried lactose monohydrate, and amorphous lactose, tablets exhibited higher reaction rate toward the Maillard reaction than the powder mixtures. Tablets containing metoclopramide hydrochloride and amorphous lactose prepared at higher pressure showed higher reaction rates than those prepared at lower pressure. This is due to increased contact between reactants and an increased amount of water retained in the tablets.

Compressive Strength↗
PubMed1999

Encapsulation of lemon oil by paste method using beta-cyclodextrin: encapsulation efficiency and profile of oil volatiles.

Microencapsulation of lemon oil was undertaken by kneading with beta-cyclodextrin, at a beta-cyclodextrin to lemon oil ratio of 88:12 (w/w). The resulting paste samples of the complex were vacuum- or spray-dried. Ten selected lemon oil flavor volatiles (alpha-pinene, sabinene, beta-pinene, beta-myrcene, limonene, gamma-terpinene, terpinolene, linalool, neral, and geranial) in the complex were analyzed periodically after 1, 2, 5, 10, 15, 20, and 30 min of kneading time. The results indicated that the levels of these volatiles were not significantly different (P > 0.05) irrespective of mixing time or type of the drying (vacuum- or spray-drying) used. An optimum mixing time was found to be 15 min, at which time the maximum encapsulation of lemon oil (97.7 mg/g of beta-cyclodextrin) was obtained in the complex powder.

Chromatography, Gas↗
PubMed2000

An investigation of the water-binding properties of protein + sugar systems.

The water-binding properties of sucrose + beta-lactoglobulin and trehalose + beta-lactoglobulin prepared by freeze-drying, spray-drying and evaporation from solution have been studied using gravimetric methods. The hydration characteristics of the individual sugars are dependent on the method of drying, and different isotherms have been recorded for each of the sample preparations. However, the initial hydration isotherms produced for the sugar + protein samples appear to be very similar for each sample type irrespective of drying method, with the sugar present in the amorphous glassy form in all cases. There is evidence of interaction between the sugar in this form and protein, specifically in the hydration region where single hydrogen-bonded water is expected to be bound. The magnitude of the interaction appears to be of the same order for both sugars. Irrespective of the method of preparation, rehydration of the sugar + protein complexes above a critical value causes a transition resulting in the sugar adopting a crystalline form and phase separation of the sugar and protein. In this crystalline form there is no evidence of interaction between the sugar and protein. For sugar + protein samples prepared by evaporation from solution, a small amount (approximately 3% by weight) of water is trapped in the complex even under extreme conditions of dehydration.

Animals↗
PubMed2006

Comparison of free radical scavenging activity of Siamese neem tree (Azadirachta indica A. Juss var. siamensis Valeton) leaf extracts prepared by different methods of extraction.

OBJECTIVE: The aim of this study was to investigate the antioxidant activity of the aqueous extracts of leaves of Siamese neem tree (Azadirachta indica A. Juss var. siamensis Valeton) from several extracting and drying methods using 2,2-diphenyl-1-picrylhydrazyl (DPPH)-scavenging assay. MATERIALS AND METHODS: The leaves of Siamese neem tree were extracted using percolation, decoction, maceration, soxhlet extraction, freeze drying or spray drying methods. The extract was tested for antioxidant activity using DPPH-scavenging assay. Thin-layer chromatography of the extract from decoction was also investigated. RESULTS: The freeze drying method gave the highest yield (51.50%, w/w) of crude extract, while decoction gave the most effective DPPH-scavenging activity (EC(50): 31.4 microg/ml). Thin-layer chromatography analysis was used to screen the leaf extract obtained using decoction, and the chromatogram showed spots corresponding to quercetin and rutin flavonoids which exhibited antioxidant activities (EC(50): 2.29 and 34.67 microg/ml, respectively). CONCLUSION: Siamese neem tree leaf extracts possessed free radical scavenging activity against the DPPH radical. The most active extract was obtained with the leaf decoction method. It showed antioxidant activity with EC(50) of 31.4 microg/ml.

Azadirachta↗
PubMed1998

[Optimization of bioavailability of pharmacons].

The authors have investigated the optimization possibilities of bioavailability of drugs as spray-drying, spray-embedding, spray-freezing, inclusion complex formation with cyclodextrin derivatives, mineral complex formation with bentonite and in vitro diffusion of products. The bioavailability of drugs may be significantly influenced with these methods.

Biological Availability↗
PubMed2006

Production of salbutamol sulfate for inhalation by high-gravity controlled antisolvent precipitation.

The purpose of this study was to produce salbutamol sulfate (SS) as a model anti-asthmatic drug using high-gravity controlled precipitation (HGCP) through antisolvent crystallisation. An aqueous solution of SS was passed through a HGCP reactor with isopropanol as antisolvent to induce precipitation. Spray drying was employed to obtain dry powders. Scanning electron microscopy, X-ray powder diffraction (XRD), density measurement, thermal gravimetric analysis, and dynamic vapour sorption were carried out to characterise the powder physical properties. The aerosol performance of the powders was measured using an Aeroliser connected to a multiple stage liquid impinger operating at 60 L/min. The HGCP SS particles were elongated with 0.1 microm in width but varying length of several mum, which formed spherical agglomerates when spray dried. The particles showed the same XRD pattern and true density (1.3g/cm3) as the raw material, indicating that they belonged to the same crystalline form. However, the spray dried agglomerates had a much lower tapped density (0.1g/cm3) than the raw material (0.6g/cm3). Compared with the powder obtained by spray drying directly from an aqueous solution, the SS powders obtained from HGCP were much less hygroscopic (0.6% versus 10% water uptake at 90% RH). The in vitro aerosol performance showed a fine particle fraction FPFloaded and FPFemitted up to 54.5+/-4.9% and 71.3+/-10.0%, respectively. In conclusion, SS powder with suitable physical and aerosol properties can be obtained through antisolvent HGCP followed by spray drying.

Aerosols↗
PubMed2002

Physical stability of redispersible dry emulsions containing amorphous sucrose.

The objective of the present study was to estimate the stability of redispersible dry emulsions containing amorphous sucrose. Dry emulsions were prepared by spray drying liquid o/w-emulsions in a laboratory spray dryer. The effect of hydroxypropyl methylcellulose (HPMC) on the glass transition temperature T(g) of spray dried sucrose-HPMC mixtures, relative to the T(g) of amorphous sucrose, was investigated. For the sucrose-HPMC mixtures the values of T(g) followed the ideal Gordon-Taylor equation up to 30% HPMC. For dry emulsions containing 40% HPMC, 30% lipid and 30% sucrose, the T(g) was increased by 12 degrees C relative to the T(g) of amorphous sucrose. The stability of the dry emulsions was investigated by a conventional stability study and by an enthalpy relaxation study. The measured enthalpy recovery of amorphous sucrose below T(g) was used to calculate molecular relaxation time parameters based on the Williams-Watts equation. The molecular mobility of amorphous sucrose at temperatures 50 degrees C below T(g) was low and negligible with respect to the shelf life stability. It was concluded that the dry emulsions are physically stable with respect to the lifetime of a pharmaceutical product when stored in dry condition and at temperatures up to 28 degrees C.

Chemistry, Pharmaceutical↗
PubMed2002

Application of slurry bridging experiments at controlled water activities to predict the solid-state conversion between anhydrous and hydrated forms using theophylline as a model drug.

The role of water activity (a(w)), relative humidity (RH) and temperature on the hydration state of theophylline has been investigated. Slurry bridging experiments at controlled water activities, using powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) to characterise the solid phase, established that the hydrate is the thermodynamically stable form of theophylline at a(w) > or = 0.5 at 4 degrees C, a(w) > or = 0.64 at 30 degrees C, and a(w) > or = 0.76 at 40 degrees C. These data were used to produce a phase stability diagram for anhydrous/hydrate theophylline versus temperature. Anhydrous theophylline was spray dried in an attempt to reduce crystallinity. The spray dried theophylline was stored at a range of temperatures (4-40 degrees C) and humidities (22-89% RH). Samples were analysed at 3, 6, 9, 26 and 52 weeks using TGA and at the 26 and 52 weeks by PXRD. The solid state stability of the spray dried theophylline closely correlated to the phase stability diagram produced using the slurry bridging experiments. The data suggest that the slurry bridging technique at controlled water activities provides an accurate method of rapidly predicting the physically stable form in anhydrous/hydrate systems.

Drug Storage↗
PubMed1977

Dimensional changes of compacts after compression.

A non-contact optical technique has been used to measure changes in the heights and diameters of compacts prepared from sodium chloride, spray dried lactose, two samples of methylcellulose powder and two spray-dried lactose-maize starch granulations. Both sodium chloride and spray dried lactose exhibited relatively small dimensional changes whilst the methylcellulose powders showed up to 30% axial and 3% radial expansion. The results are discussed in terms of the inherent properties of the materials. When the lactose was granulated with maize starch, the ratio of axial; radial strain recovery was reduced from 5-9:1 to approximately 1:1, suggesting an improved distribution of forces during compression of the granulations,

Drug Compounding↗
PubMed2004

Influenza vaccine powder formulation development: spray-freeze-drying and stability evaluation.

The purpose of this study was to develop a spray-freeze-drying (SFD) process for preparing an influenza vaccine dry powder formulation suitable for epidermal powder immunization. After preformulation of two types of flu vaccines, their dry-powder formulations were prepared by SFD. Powder properties and physical stability were determined using particle size analysis, tap density measurement, scanning electron microscopy, optical microscopy, and moisture content analysis. Chemical and biochemical stability of vaccine antigens was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, single radial immunodiffusion assay, and in vivo immunogenicity in a mouse model. We demonstrated that SFD could produce high-density particles-a critical parameter for effective skin penetration. From the stability perspective, the stress posed by SFD was mild because the antigen in the dry powder retained its stability, potency, and immunogenicity. Among several formulations screened, we noted that formulation composition has a significant role in the powder's long-term physical and biochemical stability. One formulation, in particular, containing sub-unit vaccine (45 microg of antigen in 1 mg of powder) with a tertiary mixture of trehalose, mannitol, and dextran, exhibited excellent overall stability, including acceptable biochemical stability after being exposed to a highly humid environment. After all, we have not only demonstrated the suitability of SFD to prepare powders for epidermal powder immunization but also developed a systematic formulation development strategy that allowed the optimization of an influenza vaccine dry powder formulation. More important, this study led to the selection of a formulation system that had been successfully tested in a human clinical study.

Aerosols↗
PubMedDate not supplied

Thermal analyser and micro FT-IR/DSC system used to determine the protective ability of microencapsulated squid oil.

Squid oil was microencapsulated by spray drying method. Gelatin, sodium caseinate, maltodextrin were contained in spray drying formulation with or without lecithin and microcrystalline cellulose (Avicel). The thermal stability of the unencapsulated and encapsulated squid oils was determined by pressure differential scanning calorimetry (PDSC), Fourier transform infrared (FT-IR) microscopic photometer with DSC system and themogravimetric analysis (TGA). The results indicate that the above analytical apparatus is an easy and reliable method to investigate the samples and that the microcapsule prepared by spray-dried formulation with lecithin as an emulsifier and Avicel as a stabilizer exhibits more stable thermal stability and longer shelf-life.

Animals↗
PubMed2006

Enhancement of the dissolution rate and oral absorption of a poorly water soluble drug by formation of surfactant-containing microparticles.

The slow dissolution rate exhibited by poorly water-soluble drugs is a major challenge in the drug development process. Following oral administration, drugs with slow dissolution rates generally show erratic and incomplete absorption which may lead to therapeutic failure. The aim of this study was to improve the dissolution rate and subsequently the oral absorption and bioavailability of a model poorly water-soluble drug. Microparticles containing the model drug (griseofulvin) were produced by spray drying the drug in the absence/presence of a hydrophilic surfactant. Poloxamer 407 was chosen as the hydrophilic surfactant to improve the particle wetting and hence the dissolution rate. The spray dried particles were characterized and in vitro dissolution studies and in vivo absorption studies were carried out. The results obtained showed that the dissolution rate and absolute oral bioavailability of the spray dried griseofulvin/Poloxamer 407 particles were significantly increased compared to the control. Although spray drying griseofulvin alone increased the drug's in vitro dissolution rate, no significant improvement was seen in the absolute oral bioavailability when compared to the control. Therefore, it is believed that the better wetting characteristics conferred by the hydrophilic surfactant was responsible for the enhanced dissolution rate and absolute oral bioavailability of the model drug.

Animals↗
PubMed2004

Characterization of chitosan acetate as a binder for sustained release tablets.

A chitosan derivative as an acetate salt was successfully prepared by using a spray drying technique. Physicochemical characteristics and micromeritic properties of spray-dried chitosan acetate (SD-CSA) were studied as well as drug-polymer and excipient-polymer interaction. SD-CSA was spherical agglomerates with rough surface and less than 75 microm in diameter. The salt was an amorphous solid with slight to moderate hygroscopicity. The results of Fourier transform infrared (FTIR) and solid-state (13)C NMR spectroscopy demonstrated the functional groups of an acetate salt in its molecular structure. DSC and TGA thermograms of SD-CSA as well as FTIR and NMR spectrum of the salt, heated at 120 degrees C for 12 h, revealed the evidence of the conversion of chitosan acetate molecular structure to N-acetylglucosamine at higher temperature. No interaction of SD-CSA with either drugs (salicylic acid and theophylline) or selected pharmaceutical excipients were observed in the study using DSC method. As a wet granulation binder, SD-CSA gave theophylline granules with good flowability (according to the value of angle of repose, Carr's index, and Hausner ratio) and an excellent compressibility profile comparable to a pharmaceutical binder, PVP K30. In vitro release study of theophylline from the tablets containing 3% w/w SD-CSA as a binder demonstrated sustained drug release in all media. Cumulative drug released in 0.1 N HCl, pH 6.8 phosphate buffer and distilled water was nearly 100% within 6, 16 and 24 h, respectively. It was suggested that the simple incorporation of spray-dried chitosan acetate as a tablet binder could give rise to controlled drug delivery systems exhibiting sustained drug release.

Chitosan↗
PubMed2004

Raman spectroscopic characterization of drying-induced structural changes in a therapeutic antibody: correlating structural changes with long-term stability.

We characterized the secondary structure of a therapeutic recombinant humanized monoclonal antibody (rhuMAb), formulated with different concentrations of sucrose, trehalose, and histidine and in solution, lyophilized, and spray-dried states. Quantitative secondary structure estimates were obtained using amide I band Raman spectroscopy and a previously developed spectral deconvolution procedure. On lyophilization or spray drying in the absence of sugar, the antibody underwent significant structural perturbation. The beta-sheet content decreased with corresponding gain in the turn and unordered content. With increasing amount of sucrose or trehalose, the extent of structural perturbation decreased. Eventually, at sugar-to-protein molar ratios of > or =360, almost complete structural preservation was observed. Histidine also protected the antibody against lyophilization-induced structural changes. The extent of structural perturbation immediately after lyophilization or spray drying exhibited good correlation with the rate of aggregation for the antibody during long-term storage under accelerated conditions. The results demonstrate that amide I band Raman spectroscopy could be a quick and reliable way to screen excipients and their concentrations during lyophilized or spray dried formulation development.

Antibodies, Monoclonal↗
PubMed2003

Carbamazepine/betaCD/HPMC solid dispersions. II. Physical characterization.

Solid dispersions containing carbamazepine (CBZ) associated with beta-cyclodextrin (betaCD) and/or hydroxypropyl methylcellulose were prepared by two different methods, spray-drying or physical mixture, and characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), infrared (IR) spectroscopy, and x-ray powder diffraction analysis (XRPD) studies. Scanning electron microscopy pictures showed that spray-drying produced a mixture of hollow, spherical, and partially shrunken microparticles of homogeneous materials, whereas the physical mixtures yielded heterogeneous systems in which all individual components could be identified. Thermal and IR analyses suggest the existence of a strong interaction between CBZ and excipients in spray-dried solid dispersions, but no CBZ polymorphic transition was detected by either IR spectroscopy or XRPD analysis after the spray-drying process.

Anticonvulsants↗