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PubMed2005

Deposition of insulin powders for inhalation in vitro and pharmacodynamic evaluation of absorption promoters in rats.

AIM: To prepare insulin powder for inhalation by spray-drying technology, determine the deposition of the insulin powder formulation in vitro and preliminarily investigate hypoglycemic response of the dry powder with/without absorption promoters. METHODS: The depositions of the insulin powder for inhalation were determined by the China Pharmacopoeia 2000 version addenda XH and hypoglycemic effects were evaluated by testing serum glucose with glucose oxidase-peroxidase (GOD-PAP) method. RESULTS: The depositions of the spray-dried insulin powder for inhalation were more than 40% under various humidity and their changes were not significant when air flow was no less than 18 L x min(-1). The coadministration of insulin with 8 mmol x L(-1)/dose sodium taurocholate [PA = 59.91%, Cnadir = (33 +/- 6) %] and 10 mmol x L(-1)/dose sodium deoxycholate [PA = 47.46% , Cnadir = (32 +/- 7)%] induced a significantly greater decline in blood glucose levels, while coadministration with 1% sodium caprylate, 1% sodium dodecyl sulfate, 250 microg/dose lecithin, 10 mmol x L(-1)/dose EDTA appeared to have no significant effect (P > 0.05). CONCLUSION: Insulin powder for inhalation was relatively stable under various humidity conditions and different flow current. The use of 8 mmol x L(-1)/dose sodium taurocholate and 10 mmol x L(-1)/dose sodium deoxycholate could be able to potentially improve the bioavailability of insulin by pulmonary route.

Administration, Inhalation↗
PubMed2004

Stability study of amorphous valdecoxib.

Formulation of poorly water-soluble drugs in the most stable dosage form for oral delivery perhaps presents the greatest challenge to pharmaceutical industry. Physical transformation of drug substance into its more soluble but metastable amorphous form is one of the approaches for improving dissolution rate of such drugs. The present study utilizes technique of spray drying for preparation of solid dispersions (SDs) and includes stability study of the same. Valdecoxib (VLD), a prototype of poorly water-soluble drugs, has been the drug of choice. The hydrophilic carriers selected were polyvinylpyrrolidone K30 (PVP) and hydroxypropylcellulose (HPC). SDs and pure VLD in the form of spray dried powder (SDVLD) in comparison with pure drug and corresponding physical mixtures (PMs) were initially characterized and then subjected to stability testing at ambient temperature and relative humidity up to 3 months. During initial characterization, increase in saturation solubility and dissolution rate was observed in all samples. DSC and XRPD studies of SDVLD and SDs suggested generation of amorphous form of drug. IR spectroscopy revealed presence of hydrogen bonding in SDs. During stability testing, there was gradual decrease in saturation solubility and dissolution rate of SDs, over the period of 3 months. While, saturation solubility of SDVLD dropped drastically within 15 days and was almost comparable with pure VLD. SD PVP retained the amorphous form of drug throughout stability period, whereas SD HPC and SDVLD presented incidence of crystallinity after 1 month and 15 days, respectively. This was justified by enthalpy relaxation studies in which, amorphous VLD showed considerable relaxation of enthalpy at Tg, while it was totally suppressed in SD PVP and partly in SD HPC. The study thus definitely reveals tremendous potential of solid dispersions of valdecoxib with PVP, from stability point of view.

Algorithms↗
PubMed1999

In vitro evaluation of microparticles and polymer gels for use as nasal platforms for protein delivery.

PURPOSE: Nasal delivery of protein therapeutics can be compromised by the brief residence time at this mucosal surface. Some bioadhesive polymers have been suggested to extend residence time and improve protein uptake across the nasal mucosa. We examined several potential polymer platforms for their in vitro protein release, relative bioadhesive properties and induction of cytokine release from respiratory epithelium. METHODS: Starch, alginate, chitosan or Carbopol microparticles, containing the test protein bovine serum albumin (BSA), were prepared by spray-drying and characterized by laser diffraction and scanning electron microscopy. An open-membrane system was used to determine protein release profiles and confluent, polarized Calu-3 cell sheets were used to evaluate relative bioadhesion, enhancement of protein transport and induction of cytokine release in vitro. RESULTS: All spray-dried microparticles averaged 2-4 microm in diameter. Loaded BSA was not covalently aggregated or degraded. Starch and alginate microparticles released protein more rapidly but were less adhesive to polarized Calu-3 cells than chitosan and Carbopol microparticles. Protein transport across polarized Calu-3 cells was enhanced from Carbopol gels and chitosan microparticles. A mixture of chitosan microparticles with lysophosphatidylcholine increased protein transport further. Microparticles prepared from either chitosan or starch microparticles, applied apically, induced the basolateral release of IL-6 and IL-8 from polarized Calu-3 cells. Release of other cytokines, such as IL-1beta, TNF-alpha, GM-CSF and TGF-beta, were not affected by an apical exposure to polymer formulations. CONCLUSIONS: We have described two systems for the in vitro assessment of potential nasal platforms for protein delivery. Based upon these assessments, Carbopol gels and chitosan microparticles provided the most desirable characteristics for protein therapeutic and protein antigen delivery, respectively, of the formulations examined.

Administration, Inhalation↗
PubMed2004

Microparticulate formulations for the controlled release of interleukin-2.

Interleukin 2 (IL-2) is a pleotropic growth factor essential to immune system function. Current methods of administration are limited by the necessity of hospitalization as well as dose-limiting toxicities and side effects. There is also the issue of low therapeutic concentrations at the desired site of action; for instance, in the case of solid tumor treatment. Here we describe the design of controlled-release vehicles for the local administration of IL-2 based on single (SE) and double emulsion (DE) poly(lactic-co-glycolic acid) (PLGA) systems and a newly developed class of spray-dried lipid-protein-sugar systems composed of L-alpha-dipalmitoylphosphatidylcholine (DPPC) and 0.2% Eudragit E 100. All three systems demonstrated the release of therapeutic drug quantities. Totals of 2.0, 0.5, and 2.8 microg of IL-2 (per mg of solid) were encapsulated in the SE, DE, and spray-dried formulations, respectively. The SE and DE released of 30 and 15% of the encapsulated protein, respectively, with delivery of biologically active IL-2 during the first 5 to 10 days. The lipid-protein-sugar-based system demonstrated extended sustained release of biologically active IL-2 for a period of 4 months. These systems provide a potential framework for long-term loco-regional immunotherapeutic treatment regimens.

Animals↗
PubMed2004

Changes in surface properties by granulation and physicochemical stability of granulated amorphous cefditoren pivoxil with additives.

The evaluation of the physicochemical stability of granules of amorphous cefditoren pivoxil (CDTR-PI), alone or with polymers, demonstrated that granulated amorphous CDTR-PI with hydroxypropyl methylcellulose was the most stable. We measured glass transition temperature by differential scanning calorimetry (DSC). The molecular mobility of the whole granules did not change, and it was not consistent with the results of the evaluation of physicochemical stability. Peak shifts were observed in IR spectra of amorphous CDTR-PI with polymers after granulation, and the shifts were similar to those observed for spray-dried samples. Furthermore, the shifts were not observed after the granules were ground. Acid-base parameters, which were also measured by inverse gas chromatography (IGC), changed after granulation. These results suggested that on the surface of the granules, CDTR-PI and the polymers would be mixed monomolecularly, as in the spray-dried samples. The changes in the molecular state of a drug when mixed monomolecularly with a polymer on the surface of granules were successfully confirmed by IGC and IR.

Cephalosporins↗
PubMed2003

Microcrystals for dissolution rate enhancement of poorly water-soluble drugs.

Slight dissolution rates related to poor water-solubility are one of the well-known difficulties to be covered during the development of new drug substances. The poorly water-soluble drug ECU-01, a low molecular enzyme-inhibitor with anti-inflammatory properties for oral administration, shows a poor dissolution rate. This study is intended to enhance the drug dissolution rate by using microcrystals. The common way for micronization is the milling of previously formed larger crystals. However, milling shows several disadvantages as the newly created surfaces are thermodynamically activated due to the high energy input and not naturally grown. In this study microcrystals were not produced using any cutting up techniques, but only by association. Naturally grown microcrystals were prepared by a precipitation method in the presence of stabilizing agents (e.g. gelatin, chitosan, different types of cellulose ethers) followed by spray-drying of the formed dispersion. First the drug was dissolved in acetone and then precipitated by rapid pouring an aqueous solution of the stabilizer into the drug solution. Particularly, cellulose ethers were able to form stable and homogeneous dispersions of microcrystals (mean particle size = 1 microm) showing a tight particle size distribution. By spray-drying, the drug powder was obtained. The dissolution rate is significantly enhanced (common drug: 4% after 20 min/microcrystals 93% after 20 min) due to the large surface, which is hydrophilized by adsorbed stabilizers as shown by the decreased contact angle (65 and 30 degrees, respectively).

Anti-Inflammatory Agents↗
PubMedDate not supplied

Clonazepam microencapsulation in poly-D,L-lactide-co-glycolide microspheres.

The work is aimed at the preparation and characterization of biodegradable microspheres of poly-D,L-lactide-co-glycolide (PLGA), for the controlled release of clonazepam. The solubility characteristics of this drug make it an interesting example to evaluate the performances of the two most widely used microencapsulation techniques, emulsification solvent evaporation and spray-drying. Several biodegradable PLGA copolymers have been evaluated (RG 502H, RG 503H, RG 503, Boerhinger Ingelheim). They differ in terms of molecular weight and physico-chemical characteristics. The microspheres obtained have been characterized for their morphology, physico-chemical properties (DSC) and in vitro dissolution behaviour. Between the two preparation methods, only spray-drying was suitable for the microencapsulation of clonazepam in PLGA microspheres. In vitro dissolution tests highlight that more sustained release of drug is achieved with the higher (molecular weight) polymer.

Anticonvulsants↗
PubMed2003

Biodegradable microparticles for sustained release of a new GnRH antagonist--part I: Screening commercial PLGA and formulation technologies.

The formulation of a new GnRH antagonist (degarelix) in biodegradable poly(DL-lactide-co-glycolide) (PLGA) microparticles was investigated for the development of a 3-month sustained release formulation to treat prostate cancer. The aim was to screen formulation technologies and distinct copolymers to produce microparticles (MP) of different types with good entrapment efficiency (>85%) and peptide purity (>95%) after gamma sterilization. Basically, three types of degarelix-loaded MP (4, 8 and 16% w/w nominal content) were produced with solvent and non-solvent technologies, namely double-emulsion solvent evaporation, spray-drying and two extrusion methods. Besides composition, commercial copolymers differing in residual monomer content and functional group at the carboxylic terminus (acid or ester) were characterized and employed. Peptide loading capacity and purity, as well as shape, size characteristics, and porosity of the produced microparticles were discussed in relation to technology and copolymer choice. Spray-drying and micro-extrusion were the two preferred formulation technologies because of higher entrapment efficiency and better preservation of peptide purity during production and gamma-sterilization. The impact of formulation technologies on the MP characteristics overwhelmed the impact of copolymer selection. Nevertheless, one particular polymer was discarded since it was more susceptible towards radiolytic degradation. The resulting degarelix-MP will be tested in a biological assay for selection of the formulation based on performance.

Biotransformation↗
PubMed2000

Effect of ultrasound emulsification on cheese aroma encapsulation by carbohydrates.

The encapsulation of liquid cheese aroma (20%) in different carbohydrate matrices by spray-drying was investigated. Carbohydrate stabilized emulsions have been prepared by two emulsifying methods, ultrasonic or Ultra-Turrax treatments, and have been compared in terms of emulsion stability and encapsulation efficiency. The use of ultrasound is particularly effective to obtain a stable emulsion with maltodextrin as support, which is known for poor emulsification properties. In the same way, the spray-dried maltodextrin microcapsules were more effective for retaining cheese aroma when ultrasound (12.7 g/100 g of dry powder) was used for the emulsification step rather than Ultra-Turrax (10.7 g/100 g of dry powder). In terms of encapsulation efficiency, the best system of cheese aroma encapsulation is obtained using ultrasound for the emulsification step and modified starch as support (94.3%). With this support, the positive effect of ultrasound resulted in a lower microcaspsule size and in a higher aroma retention than when Ultra-Turrax was used (83.3%). Studies on the aroma profiles showed changes after encapsulation that depend not only on the nature of the support and the emulsification method but also on the interactions between the aroma compound and the matrix. In terms of flavor quality, the best system of cheese aroma encapsulation is obtained using ultrasound and maltodextrin as support.

Carbohydrates↗
PubMed1998

Evaluation of enzymatically modified potato starches in diets for weanling pigs.

We conducted three growth trials to evaluate replacing carbohydrate sources with enzymatically modified potato starches in diets for weanling pigs. In Exp. 1, 180 pigs (initially 5.3 kg and 21+/-2 d of age) were used to compare the effects of corn (36.5%), edible-grade oat flour (36.5%), two enzymatically modified potato starches (12%), and added lactose (12%) on pig performance. Potato Starch 1 had a dextrose equivalent (DE) of 6 and Potato Starch 2 had a DE of 20; both were spray-dried maltodextrans. Pigs that were fed Potato Starch 2 had greater (P<.05) ADG and ADFI than pigs fed diets that contained corn or oat flour from d 0 to 14 after weaning, and pigs fed either Potato Starch 1 or added lactose had intermediate ADG and ADFI. However, for the overall trial (d 0 to 35), no differences (P>.10) in growth performance were observed. In Exp. 2, 198 pigs (initially 4.3 kg and 19+/-2 d of age) were used to determine whether modified Potato Starch 2 could replace a portion of the corn or lactose in the diet. The control diet contained 10% dried whey, and additional treatments were formulated by adding 7 or 14% modified Potato Starch 2 or lactose in place of corn. A positive control diet was formulated containing 29% dried whey. From d 0 to 14 after weaning, increasing dietary lactose improved (linear, P<.04) ADG and ADFI. Increasing the potato starch had no effect on ADG but increased ADFI (linear, P<.02). In Exp. 3, 180 pigs (initially 3.9 kg and 14+/-3 d of age) were used to evaluate Potato Starch 2 or 3 (DE = 30, a spray-dried glucose syrup) as replacements for either corn or lactose in the diet. Pigs were fed a control diet containing 15% dried whey and 12% added lactose. Twelve percent modified Potato Starch 2 or 3 replaced either corn or lactose in the diet on a wt/wt basis. From d 0 to 14 and d 0 to 21, pigs fed either modified potato starch substituted for corn had greater (P<.07) ADG than those fed the control diet. Pigs fed diets with either modified starch substituted for lactose had similar ADG as those fed the control diet. These results suggest that when substituted for corn, Potato Starch 2 can improve growth performance of weanling pigs.

Animal Feed↗
PubMed2002

Stabilization of cucurbitacin E-glycoside, a feeding stimulant for diabroticite beetles, extracted from bitter Hawkesbury watermelon.

Cucurbitacins are feeding stimulants for diabroticite beetles, including corn rootworms and cucumber beetles, which can be added to a bait containing an insecticide thereby reducing the levels of other insecticide treatments needed to control these pests. One of them, cucurbitacin E-glycoside, is water soluble and easily processed from mutant bitter Hawkesbury watermelons (BHW) that express elevated levels of cucurbitacin. Storage of BHW extract at room temperature resulted in a 92% reduction of cucurbitacin E-glycoside over two months, while refrigeration or freezing resulted in a 60% loss of the active ingredient during this time. The loss of the active ingredient was correlated with an increase in BHW extract pH from 5 to greater than 9. The increase in pH of the BHW extracts at room temperature appeared to be due to the growth of certain bacteria, especially Bacillusspp. In refrigerated extracts, the pH remained relatively constant, and bacterial growth was dominated by bacteria such as Lactobacilli. An alternative to refrigeration is concentration of BHW extract. One means of concentration is spray drying, but the high sugar content of the BHW extract (20mg/ml glucose, 40mg/ml fructose) makes this technique impractical. Fermentation of the BHW extract by the yeast, Saccharomyces boulardii, eliminated the sugars and did not raise the pH nor alter the cucurbitacin E-glycoside content of the extract. Elimination of the sugars by fermentation produced an extract that could be successfully spray dried. BHW extract fermented by S. boulardii produced a higher level of feeding stimulation for spotted cucumber beetles in laboratory choice tests. When applied to cucumbers, there was no difference in control of spotted and striped cucumber beetles between baits of fresh or fermented juices combined with the same insecticide.

Animals↗
PubMedDate not supplied

Influences of process parameters on preparation of microparticle used as a carrier system for omega - 3 unsaturated fatty acid ethyl esters used in supplementary nutrition.

Microparticles were prepared by complex coacervation to encapsulate eicosapentaenoic acid ethyl ester (EPA-EE) for incorporation into foods as a nutrition supplement. Gelatin and acacia were used in the coacervation process. With an increasing oil/polymer ratio, both yield and encapsulation rate decreased; with an increasing homogenization time, the yield remained constant while the encapsulation rate slightly increased. Several particle hardening techniques were examined and their influence on particle structure, yield and encapsulation rate were examined. Ethanol hardening was compared to cross-linking with dehydroascrobic acid with respect to both yield and encapsulation rate. The particle diameters for both formulations were similar (ethanol: 38.4 +/- 4.1 microm; cross-linking: 41.8 +/- 3.0 microm). Spray-drying of the coacervates led to the smallest particles (5.2 +/- 1.1 microm), lowest yield and encapsulation rate. All microencapsulation products were assayed for their storage stability over 4 weeks with respect to the oxidation of the encapsulated omega - 3 unsaturated fatty acid ester inside the particles. Hardening with ethanol showed the lowest amount of peroxides: particle wall cross-linking by dehydroascorbic acid and spray-drying were observed to be less protective. All microparticles were characterized for their internal structure with confocal laser scanning microscopy (CLSM) after fluorescence labelling of the polymers, in order to localize the oil phase and visualize the distribution of the polymers in the coacervates. With increasing homogenization time, the internal structure changed stepwise from a capsule structure (core/wall) towards a matrix structure. For all experiments, a homogeneous distribution for both polymers, gelatin and acacia was observed inside the particle wall. No influence of the different particle hardening procedures on the polymer distribution was found.

Dehydroascorbic Acid↗
PubMed2005

Novel sustained release microspheres for pulmonary drug delivery.

A novel process for generating sustained release (SR) particles for pulmonary drug delivery is described. High purity nanoparticles of a hydrophilic, ionised drug are entrapped within hydrophobic microspheres using a spray-drying approach. Sustained release of the model drug, terbutaline sulphate (TS), from the microspheres was found to be proportional to drug loading and phospholipid content. Microspheres with a 33% drug loading exhibited sustained release of 32.7% over 180 min in phosphate buffer. Release was not significantly different in simulated lung fluids. No significant burst release was observed which suggested that nanoparticles were coated effectively during spray-drying. The absence of nanoparticles at the microsphere surface was confirmed with confocal microscopy. The sustained release microspheres were formulated as a carrier-free dry powder for inhalation, and exhibited a favourable Fine Particle Fraction (FPF) of 46.5+/-1.8% and Mass Median Aerodynamic Diameter (MMAD) of 3.93+/-0.12 microm.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2006

In vitro and in vivo release of gentamicin from biodegradable discs.

Osteomyelitis is an infection of the bone and successful treatment involves the removal of the affected bone and the tissue by a surgical procedure following prolonged systemic and local antibiotic therapy for 4 to 6 weeks. The current local treatment is done by poly methyl methacrylate (PMMA) beads loaded with gentamicin and PMMA, being nondegradable, is to be removed by a second surgical procedure. The current study aims to develop a biodegradable composition that gives sustained release and hence reducing the need for a second surgery. Gentamicin-loaded discs were produced by compressing microparticle-gentamicin mixture obtained by spray drying a mixture of gentamicin in a solution of a biodegradable polymer. Different copolymers of poly (DL-lactic-co-glycolic acid) (PLGA) were used to study the effect of copolymer ratio and the hydrophilic-hydrophobic nature of the polymer. Theoretical drug loading up to 25% were studied and it was observed that 10% drug loading was optimum for gentamicin to be used as solid in spray drying. The results showed that about 60% of the drug is released in about 5 to 6 days and the remaining drug is released in about 30 days in total. An in vivo study was carried on rabbit femur and the local area and systemic concentration of gentamicin was monitored. It was observed that the local area concentration of gentamicin was above minimum inhibitory concentration for more than 20 days and this was also validated by computer simulations.

Animals↗
PubMed2002

Preparation of microparticulate beta-glucan from Saccharomyces cerevisiae for use in immune potentiation.

AIMS: To develop a method for the preparation of an immunologically active, homogeneous, nonaggregated, microparticulate beta-glucan-containing material from the budding yeast Saccharomyces cerevisiae. METHODS AND RESULTS: Using a combination of sonication and spray-drying, a homogeneous preparation of 1-2-mu diameter beta-glucan-containing particles was made from alkali- and acid-insoluble yeast cell wall material. This microparticulate beta-glucan remained in suspension longer and, following oral administration at 0.1 mg kg(-1) for 14 d, enhanced phagocytosis of mouse peritoneal macrophages significantly better than did aggregated beta-glucan particles. CONCLUSIONS: A new sonication and spray-drying method can be employed to overcome the problem of aggregation of beta-glucan microparticles in aqueous media. SIGNIFICANCE AND IMPACT OF THE STUDY: A microparticulate form of beta-glucan that remains in suspension longer for pharmaceutical applications and has superior immune potentiation characteristics has been developed.

Adjuvants, Immunologic↗
PubMedDate not supplied

Gastro-resistant microspheres containing ketoprofen.

Ketoprofen gastroresistant microspheres were prepared by spray-drying using common pH dependent polymers, such as Eudragit S and L, CAP, CAT and HPMCP. The long ketoprofen recrystallization time was a serious hindrance to the preparation of microspheres having a drug content higher than 35%. Microspheres were characterized by scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry and in vitro dissolution studies, and used for the preparation of tablets. During this step, the compaction ability of the spray-dried powders was measured. While the compressibility of the microspheres containing the enteric cellulosic derivatives are not acceptable and different from those of the microcrystalline cellulose, the compaction properties of ketoprofen/Eudragit L or S microspheres are comparable to those of the Avicel PH 101. In vitro dissolution studies were performed on the microspheres and the tablets. All microspheres showed a good gastroresistance, but some differences among the five polymers in reducing drug release at low pH values are present. Acrylic polymers (Eudragit L or S) are considerably more effective than the cellulosic derivatives CAP and CAT, while the HPMCP profile is in an intermediate position. These differences are erased by the microspheres compression process. In HCl 0.1 N, the percentage of ketoprofen released from the tablets is always close to zero, independently from the polymer used.

Acrylates↗
PubMed1986

[A rapid computer-assisted method for the determination of urea in dairy products: skim milk powder from various sources].

The enzymatic determination of urea in spray-dried skim milk powders was transferred to a computer aided photometric analysing system. Sample preparation is optimal using ultrafiltration, but the direct use of a milk sample is also possible with this system. The precision including sample preparation as coefficient of variation was about 0.69%, the standard deviation of the assay was 0.115-0.135 at an average content of 5.4-5.5 mg urea per 100 ml skim milk. The method was tested on 147 spray-dried skim milk powders, which were of varying origin and collected at different times of the year (Jan.-Oct.). In this way a representative survey for the urea content of a great number of skim milk powders was possible. It was also shown, that the urea content is highly affected by season. It is very constant from February to May (0.25-0.26%), and rises from June to October up to nearly 0.32%.

Animals↗
PubMed2001

The use of inverse phase gas chromatography to study the change of surface energy of amorphous lactose as a function of relative humidity and the processes of collapse and crystallisation.

The purpose of this study was to assess the effect of relative humidity (RH) on the surface energy of amorphous lactose. Two samples of amorphous lactose were investigated; a spray dried 100% amorphous material and a ball milled sample of crystalline lactose. The milled sample had less than 1% amorphous content by mass, but on investigation at 0% RH, yielded surface energies comparable to those obtained from the 100% amorphous material, indicating that the surface was amorphous. The effect of increasing humidity was to reduce the dispersive surface energy of the two samples from 36.0 +/- 0.14 and 41.6 +/- 1.4 mJ m(-2) at 0% RH for the spray dried and milled samples respectively, to a value comparable to that obtained for the crystalline alpha-lactose monohydrate of 31.3 +/- 0.41 mJ m(-2). The change in surface energy due to water sorption was only reversible up to 20% RH; after exposure to higher RH values subsequent drying did not result in a return to the original surface energy of the amorphous form. This shows that the surface is reorganising as the glass transition temperature (Tg) is reduced, even though the sample has not collapsed or crystallised. It was possible to follow the collapse behaviour in the column with ease, using a number of different methods.

Absorption↗