Simultaneous quantification of 22R and 22S epimers of budesonide in human plasma by ultra-high-performance liquid chromatography-tandem mass spectrometry: application in a stereoselective pharmacokinetic study

Budesonide (BUD) is used as a mixture of 22R and 22S epimers for the topical treatment of asthma, rhinitis, and inflammatory bowel disease. To study stereoselectivity in the pharmacokinetics of each epimer, we developed a stereoselective and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of 22R and 22S epimers of BUD in human plasma. The epimers of BUD were extracted from plasma using n-hexane/dichloromethane/isopropanol (2:1:0.1, v/v/v) under alkaline conditions. Baseline separation was obtained within 7min on an Acquity UPLC BEH C18 (50mm×2.1mm, 1.7μm) column using an isocratic mobile phase consisting of acetonitrile/5mM ammonium acetate/acetic acid (29:71:0.142, v/v/v) at a flow rate of 0.7mL/min. Mass spectrometric detection was performed in a multiple reaction monitoring mode using the m/z 489→357 transition for BUD epimers and the m/z 497→357 transition for the internal standard d8-BUD epimers. Calibration curves were linear over the concentration ranges of 5.0-500 and 5.0-3000pg/mL for 22R-BUD and 22S-BUD, respectively. The lower limit of quantification was 5.0pg/mL for both epimers. The method was successfully applied in a pharmacokinetic study of BUD controlled-release capsules in humans. Consistent differences in the pharmacokinetics of the 22R and 22S epimers were observed, the AUC(0-∞) of 22S-BUD was approximately six times higher than that of 22R-BUD, and the 22S-/22R-BUD ratio of total body clearance was 0.17.

Preparation, in vitro and in vivo evaluation of budesonide loaded core/shell nanofibers as oral colonic drug delivery system

Budesonide (BUD) loaded ethylcellulose (EC)-core/Eudragit S100-shell nanofibers (BUD-core/shell-NFs) have been successfully prepared using a coaxial electrospinning technique. The drug encapsulation efficiency was 90.48%. SEM and TEM analysis showed that fine core-shell structured nanofibers with an average diameter 190 nm and uniform core diameters 74 nm were prepared. The BUD-loaded Eudragit S100/EC composite nanofibers (BUD-NFs) were prepared using a blend electrospinning method and used as a control. In vitro release tests in HCl 0.1 N, phosphate buffer solutions pH 6.8 and 7.4 were studied. Moreover, the colon-specific characteristics were directly proven in vivo by the content of BUD in different segments of the gastrointestinal (GI) tract in rats after oral administration. Taken together, the results confirmed that BUD-core/shell-NFs had desired pH-dependent drug release profile, displayed a sustained and complete drug release in the colon, as well as protected BUD from being released completely in the upper portion of the GI tract. Compared with BUD-NFs, the BUD-core/shell-NFs have much better potential to be developed as oral colon-specific drug delivery system (OCDDS) to overcome the disadvantages of current oral formulations of BUD.

Investigation and comparison of colon specificity of novel polymer khaya gum with guar gum

To investigate the colon specificity of novel natural polymer khaya gum and compare with guar gum. Release profile of tablets was carried out in presence and absence of rat cecal contents. The fast disintegrating core tablets of budesonide, were initially prepared by direct compression technique. Later, these tablets were coated with khaya gum or guar gum. After suitable pre compression and post compression evaluation, these tablets were further coated using Eudragit L-100 by dip coating technique. X-ray images were taken to investigate the movement, location and the integrity of the tablets in different parts of gastro intestinal tract in rabbits. The release profiles revealed that khaya gum or guar gum, when used as compression coating, protected the drug from being released in the upper parts of the gastro intestinal tract to some extent but the enteric coated formulations completely protected the drug from being released in the upper parts of the gastro intestinal tract, and released the drug in the colon by bacterial degradation of gums. It was found that both the polysaccharide polymers exhibited different release profiles in presence and absence of rat cecal contents. However, further enteric coat helped in targeting the drug to colon very effectively. Better dissolution models revealed the colon specificity of polysaccharides and alone can not be used either for targeting the drug to the colon or for sustaining or controlling the release of drug.

Intratracheal budesonide-poly (lactide-co-glycolide) microparticles reduce oxidative stress, VEGF expression, and vascular leakage in a benzo(a)pyrene-fed mouse model

The purpose of this study was to determine whether intratracheally instilled polymeric budesonide microparticles could sustain lung budesonide levels for one week and inhibit early biochemical changes associated with benzo(a)pyrene (B[a]P) feeding in a mouse model for lung tumours. Polymeric microparticles of budesonide-poly (dl-lactide-co-glycolide) (PLGA 50:50) were prepared using a solvent evaporation technique and characterized for their size, morphology, encapsulation efficiency, and in-vitro release. The microparticles were administered intratracheally (i.t.) to B[a]P-fed A/J mice. At the end of one week drug levels in the lung tissue and bronchoalveolar lavage (BAL) were estimated using HPLC and compared with systemic (intramuscular) administration. In addition, in-vivo end points including malondialdehyde (MDA), glutathione (GSH), total protein levels and vascular endothelial growth factor (VEGF) in BAL, and VEGF and c-myc mRNA levels in the lung tissue were assessed at the end of one week following intratracheal administration of budesonide microparticles. Budesonide-PLGA microparticles (1–2 μm), with a budesonide loading efficiency of 69–94%, sustained in-vitro budesonide release for over 21 days. Compared with the intramuscular route, intratracheally administered budesonide-PLGA microparticles resulted in higher budesonide levels in the BAL and lung tissue. In-vivo, B[a]P-feeding increased BAL MDA, lung VEGF mRNA, lung c-myc mRNA, BAL total protein, and BAL VEGF levels by 60, 112, 71, 154, and 78%, respectively, and decreased BAL GSH by 62%. Interestingly, intratracheally administered budesonide-PLGA particles inhibited these biochemical changes. Thus, biodegradable budesonide microparticles sustained budesonide release and reduced MDA accumulation, GSH depletion, vascular leakage, and VEGF and c-myc expression in B[a]P-fed mice, indicating the potential of locally delivered sustained-release particles for inhibiting angiogenic factors in lung cancer.

Chemical and physical compatibility of levalbuterol inhalation solution concentrate mixed with budesonide, ipratropium bromide, cromolyn sodium, or acetylcysteine sodium

BACKGROUND

Medications are frequently combined in the nebulizer cup, so it is important to determine their chemical and physical compatibility.

OBJECTIVE

To determine the chemical and physical compatibility of levalbuterol with ipratropium bromide, cromolyn sodium, acetylcysteine sodium, and budesonide.

METHODS

We mixed one dose of levalbuterol inhalation solution concentrate (1.25 mg/0.5 mL) with one dose of ipratropium bromide (0.5 mg/2.5 mL), cromolyn sodium (20 mg/2 mL), acetylcysteine sodium (1,000 mg/5 mL), or budesonide (0.5 mg/2 mL). Immediately after mixing the 2 drugs (time zero [T(0)]), and again after 30 min at room temperature (T(30)), we visually inspected the admixtures, measured their pH, and conducted high-pressure liquid chromatography (HPLC).

RESULTS

There was no evidence of physical incompatibility with these drugs combinations. With all the admixtures, both drugs were chemically stable for at least 30-min. Admixture pH had not changed significantly at T(30). Drug recovery was 93.2-102.6% of the initial or control values.

CONCLUSIONS

The 2-drug admixtures we studied were compatible for at least 30 min at room temperature.

Improved Efficiency of Budesonide Nebulization Using Surface-Active Agents

Our aim was to improve the efficiency of nebulised budesonide using surface-active agents. Cationic, anionic, and nonionic detergents were added to commercial budesonide suspension, and the particle size distribution during nebulization was measured using both cascade impaction and laser diffraction. Our results showed that the emitted dose was increased after addition of cationic (p < 0.001) and nonionic detergents (p < 0.01) compared with the commercial formulation alone. The respirable fraction was increased for all detergent formulations (p < 0.001) compared with the commercial formulation. We concluded that cationic and nonionic detergent increased the total output of budesonide from the Sidestream. All detergent formulations increased the respirable fraction of nebulized budesonide.

Influence of Impactor Operating Flow Rate on Particle Size Distribution of Four Jet Nebulizers

When a nebulizer is evaluated by the Andersen Cascade Impactor (ACI), the flow rate is generally maintained at 28.3 L/min, as recommended by the manufacturer. However, the nebulizer flow rate that a patient inhales is only around 18 L/min. Because the drive flow of a nebulizer is approximately 6-8 L/min, the nebulized drug is mixed with outside air when delivered. Evaluating impactor performance at the 28.3 L/min flow rate is less than ideal because an additional 10 L/min of outside air is mixed with the drug, thereby affecting the drug size distribution and dose before inhalation and deposition in the human lung. In this study we operated the ACI at an 18.0 L/min flow rate to test whether the effect of the changing ambient humidity was being exaggerated by the 28.3 L/min flow rate. The study was carried out at three different relative humidity levels and two different impactor flow rates with four commercially available nebulizers. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) of the droplets were found to increase when the impactor was operated at a flow rate of 18 L/min compared to that of 28.3 L/min. The higher MMAD and GSD could cause the patient to inhale less of the drug than expected if the nebulizer was evaluated by the ACI at the operating flow rate of 28.3 L/min.

Preparation of Budesonide-Poly (Ethylene Oxide) Solid Dispersions Using Supercritical Fluid Technology

The purpose of this study was to investigate the possibility of preparing solid dispersions of the poorly soluble budesonide by supercritical fluid (SCF) technique, using poly (ethylene oxide) (PEO) as a hydrophilic carrier. The budesonide-PEO solid dispersions were prepared, using supercritical carbon dioxide (SC CO(2)) as the processing medium, and characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), solubility test and dissolution test in order to understand the influence of the SCF process on the physical status of the drug. The endothermic peak of budesonide in the SCF-treated mixtures was significantly reduced, indicating that budesonide was in amorphous form inside the carrier system. This was further confirmed by SEM and PXRD studies. The enhanced dissolution rates of budesonide were observed from SCF-treated budesonide-PEO mixtures. The amorphous characteristic of the budesonide, the better mixing of drug and PEO powders in the presence of SC CO(2), together with the improved wettability of the drug in PEO, produced a remarkable enhancement of the in vitro drug dissolution rate. Thus, budesonide-PEO solid dispersions with enhanced dissolution rate can be prepared using organic solvent-free SCF process.

Chitosan coated Ca–alginate microparticles loaded with budesonide for delivery to the inflamed colonic mucosa

Using a novel one-step spray-drying process uncoated and Eudragit S 100 coated chitosan-Ca-alginate microparticles efficiently loaded with budesonide (BDS), with bioadhesive and controlled release properties in GIT, were prepared. Microparticles were spherical with mean particle size of 4.05-5.36 microm, narrow unimodal distribution and positive surface charge. A greater extent of calcium chloride limited the swelling ratio of beads, while swelling behaviour of coated beads was mainly determined by properties of enteric coating. Comparing the release profiles of formulations, under different pH conditions, influence of polymer properties and concentration of cross-linker on the rate and extent of drug release was evident. Coating has successfully sustained release of BDS in buffers at pH 2.0 and 6.8, while providing potential for efficient release of BDS at pH 7.4. Release data kinetics indicated influence of erosion and biodegradation of polymer matrix on drug release from microparticles. Prepared formulations were stable for 12 months period at controlled ambient conditions. In conclusion coated microparticles prepared by one-step spray-drying procedure could be suitable candidates for oral delivery of BDS with controlled release properties for local treatment of inflammatory bowel diseases.

Multilayer PVA adsorption onto hydrophobic drug substrates to engineer drug-rich microparticles

Despite the availability of numerous crystal engineering techniques, generating drug-rich microparticles with a predetermined size, morphology and crystallinity still represents a significant challenge. A microparticle manufacturing method has recently been developed that attempts to 'shield' the physicochemical properties of micronised drugs by the application of a microfine polymer coating. The aims of this study were to investigate the nature of the drug-polymer interactions and determine the effects of this manufacturing strategy upon release of the drug from the microparticles. The adsorption of poly(vinyl alcohol) (PVA) on the micronised hydrophobic drug surface was found to reach equilibrium between 23 and 27 h. The Freundlich isotherm model was shown to give the most accurate fit to the experimental data and thus multilayer adsorption was assumed. The adsorptive capacity (1/n) was specific to the substrate and PVA grade. An increase in the PVA (%) hydrolysis value caused 1/n to increase from 0.76 to 1.05 using budesonide and from 0.31 to 0.79 when betamethasone valerate (BMV) was used. Increasing the molecular weight of the adsorbing polymer caused a reduction in the strength of PVA-adsorbate interaction when budesonide was used as the substrate (from 0.76 to 0.59), whereas a three-fold increase (from 0.31 to 0.86) was achieved when the BMV substrate was employed. A proportion of the adsorbed polymer was shown to remain associated with the substrate during the spray-drying process and the polymer coating resulted in a significantly higher (p<0.05, ANOVA) amount of drug release in 60 min (ca. 100%) compared to budesonide alone.

Low-voltage electrohydrodynamic (EHD) spray drying of respirable particles

Spray drying is a widely used process to produce pharmaceutical powders. In traditional spray drying, the particle size distribution is wide and not well controlled. Using EHD atomization for spray drying offers a possibility to tailor the particle size and morphology. In conventional EHD spray drying, the generated particles are charged and need to be discharged to avoid Rayleigh breakup. Discharging adds complexity to the process and eliminates the possibility to collect the powder using an electric field. The present work describes a novel EHD spray drying setup based on a low-voltage nozzle. The low-voltage nozzle imparts moderate charge to the droplets, which makes discharging unnecessary. The charged particles can be controlled and collected by using an auxiliary electric field. The EHD spray dryer has been characterized in terms of particle size, particle morphology, process output, and yield. The size distribution of the generated particles is very narrow. Both porous and completely spherical particles can be produced. The yield of small-scale bench-top equipment was 20%, which is similar to the yield of a small-scale conventional spray dryer. The effective output with five nozzles was 75 mg/hr of dry powder. Because of the repelling forces associated with the unipolarly charged droplets, the number of nozzles can be increased without risking coalescence.

The ester group: how hydrofluoroalkane-philic is it?

Pressurized metered-dose inhalers (pMDIs) have been recognized as potential devices for the delivery of systemically acting drugs, including biomolecules, to and through the lungs. Therefore, the development of novel excipients capable of imparting stability to suspension formulations in hydrofluoroalkane (HFA) propellants is of great relevance because many of the drugs of interest are poorly soluble in HFAs. In this work, we use ab initio calculations and chemical force microscopy (CFM) to determine the HFA-philicity of the biodegradable and biocompatible ester moiety quantitatively. The complementary information obtained from the binding energy calculations and adhesion force measurements are used to gain microscopic insight into the relationship between the chemistry of the moiety of interest and its solvation in HFA. A lactide (LA)-based copolymer surfactant was synthesized and characterized, and its ability to stabilize a dispersion of micronized budesonide in HFA227 was demonstrated. These results corroborate the ab initio calculations and CFM and show that the LA-based moiety is a suitable candidate for enhancing the stability of dispersions in HFA-based pMDIs.

Compressor/nebulizers differences in the nebulization of corticosteroids. The CODE study (Corticosteroids and Devices Efficiency)

BACKGROUND

Nebulization is a common method of medical aerosol generation and it is largely used by adults and children all over the world, both for emergency treatment of acute illness and for long-term home treatment of lung diseases. The aim of this study was to determine the differences in nebulization of inhaled corticosteroids among four representative types of compressor/nebulizers.

METHODS

Twelve compressor/jet nebulizers from four commercial sources were studied (three for each type): Clenny (MEDEL), Turbo Boy/LC Plus (PARI), Nebula Nuovo/MB5 (MARKOS MEFAR) and Maxaer (ARTSANA) compressor/Sidestream (Medic-Aid Ltd.) nebulizer. We compared the required time for the treatment (nebulization time), output/minutes, compressor pressures, and aerosol characteristics of inhaled corticosteroids: Beclomethasone dipropionate, Flunisolide, Fluticasone propionate and Budesonide.

RESULTS

Nebulization Times showed a significant difference between nebulizer and inhaled corticosteroids for Clenny, Turbo Boy, and Maxaer. A considerable difference in the output of nebulized drugs was observed through the compressors/nebulizers. MMAD of all inhaled corticosteroids was significantly different among the four nebulizers. The percentage of particles <5 microm (respirable range) was high for all devices with beclomethasone and budesonide (> 90%), whereas with flunisolide was good only for Clenny (98.8%) and Maxaer (96.3%), and with fluticasone only for Clenny (98%), Turbo Boy (99.1%), and Maxaer (86%). Also percentage of particles <2 microm showed significant variability among the devices.

CONCLUSIONS

Our results clearly demonstrate that compressor/nebulizer unit plays a key role in the effectiveness of the treatment during inhaled corticosteroid therapy, and that several differences exist in the performance of the different nebulizers studied. Therefore, the device has the same importance of the compound to reach the best clinical response in the inflammatory diseases of the lower airways.

Prevention of peritoneal adhesions with an in situ cross-linkable hyaluronan hydrogel delivering budesonide

Peritoneal adhesions are tissue connections that form within the abdominopelvic cavity following surgery or other injuries. They can cause major medical complications. Barrier devices and pharmacological agents have been used to prevent adhesion formation, with mixed success. We hypothesize that an adhesion barrier which also delivers anti-adhesion drugs can address both physical and physiological causes for adhesion formation. Here, we describe an in situ cross-linking hyaluronan hydrogel (barrier device) containing the glucocorticoid receptor agonist budesonide. Budesonide was chosen because of the known role of inflammation in adhesion formation, hyaluronan because of its known biocompatibility in the peritoneum. The system, consisting of two cross-linkable precursor liquids, was applied using a double-barreled syringe, forming a flexible and durable hydrogel in less than 5 s. We applied this formulation or controls to the injured sites after the second injury in a severe repeat sidewall defect-cecum abrasion model of peritoneal adhesion formation in the rabbit. Large adhesions (median area 15.4 cm(2)) developed in all saline-treated animals. Adhesion formation and area were slightly mitigated in animals treated with budesonide in saline (median area 5.0 cm(2)) or the hydrogel without budesonide (median area 4.9 cm(2)). The incidence and area of adhesions were dramatically reduced in animals treated with budesonide in the hydrogel (median area 0.0 cm(2)). In subcutaneous injections in rats, budesonide in hydrogel reduced inflammation compared to hydrogel alone. In summary, budesonide in a hyaluronan hydrogel is easy to use and highly effective in preventing adhesions in our severe repeated injury model. It is a potentially promising system for post-surgical adhesion prevention, and suggests that the effectiveness of barrier devices can be greatly enhanced by concurrent drug delivery.

Transformation of pharmaceutical compounds upon milling and comilling: the role of T(g)

Milling is a usual process used in the course of drug formulation, which however may change the physical nature of the end product. The diversity of the transformations of organic compounds upon milling has been widely demonstrated in the pharmaceutical literature. However, no effort has still been devoted to study the correlation between the nature of the transformation and the milling conditions. Results clarifying such transformations are shortly reviewed with special attention paid to the temperature of milling. The importance of the position of the glass transition temperature compared with that of milling is demonstrated. It is shown that decreasing the milling temperature leads to an increase of the amorphization tendency whereas milling above T(g) can produce a crystal-to-crystal transformation between polymorphic varieties. These observations contradict the usual suggestion that milling transforms the physical state only by a heating effect which induces a local melting. Equilibrium thermodynamics does not seem appropriate for describing the process. The driven alloys concept offers a more rational framework to interpret the effect of the milling temperature. Other results are also presented, which demonstrate the possibility for milling to form low temperature solid-state alloys that offer new promising ways to stabilize amorphous molecular solids.

Inhibition of allergen-induced airway remodelling by tiotropium and budesonide: a comparison

Chronic inflammation in asthma and chronic obstructive pulmonary disease drives pathological structural remodelling of the airways. Using tiotropium bromide, acetylcholine was recently identified as playing a major regulatory role in airway smooth muscle remodelling in a guinea pig model of ongoing allergic asthma. The aim of the present study was to investigate other aspects of airway remodelling and to compare the effectiveness of tiotropium to the glucocorticosteroid budesonide. Ovalbumin-sensitised guinea pigs were challenged for 12 weeks with aerosolised ovalbumin. The ovalbumin induced airway smooth muscle thickening, hypercontractility of tracheal smooth muscle, increased pulmonary contractile protein (smooth-muscle myosin) abundance, mucous gland hypertrophy, an increase in mucin 5 subtypes A and C (MUC5AC)-positive goblet cell numbers and eosinophilia. It was reported previously that treatment with tiotropium inhibits airway smooth muscle thickening and contractile protein expression, and prevents tracheal hypercontractility. This study demonstrates that tiotropium also fully prevented allergen-induced mucous gland hypertrophy, and partially reduced the increase in MUC5AC-positive goblet cell numbers and eosinophil infiltration. Treatment with budesonide also prevented airway smooth muscle thickening, contractile protein expression, tracheal hypercontractility and mucous gland hypertrophy, and partially reduced MUC5AC-positive goblet cell numbers and eosinophilia. This study demonstrates that tiotropium and budesonide are similarly effective in inhibiting several aspects of airway remodelling, providing further evidence that the beneficial effects of tiotropium bromide might exceed those of bronchodilation.

Crystal structure changes of gamma-cyclodextrin after the SEDS process in supercritical carbon dioxide affect the dissolution rate of complexed budesonide

PURPOSE

The present study describes the crystal structure changes of gamma-cyclodextrin (gamma-CD) during the solution enhanced dispersion by supercritical fluids (SEDS) process and its effect on dissolution behaviour of complexed budesonide.

MATERIALS AND METHODS

gamma-CD solution (10 mg/ml in 50% ethanol) was pumped together with supercritical carbon dioxide through a coaxial nozzle with or without a model drug, budesonide (3.3 mg/ml). The processing conditions were 100 b and 40, 60 or 80 degrees C. gamma-CD powders were characterised before and after vacuum-drying (2-3 days at RT) with XRPD, SEM and NMR. Budesonide/gamma-CD complexation was confirmed with DSC and XRPD. The dissolution behaviour of complexed budesonide was determined in aqueous solution (1% gamma-CD, 37 degrees C, 100 rpm).

RESULTS

During the SEDS process (100 b, 40 and 60 degrees C), gamma-CD and budesonide/gamma-CD complexes crystallized in a tetragonal channel-type form. The vacuum-drying transformed crystalline gamma-CD into amorphous form while the complexes underwent a tetragonal-to-hexagonal phase transition. The increase in the processing temperature decreased the crystallinity of gamma-CD. At 80 degrees C, amorphous gamma-CD was obtained while the complexes crystallized in a hexagonal channel-type form. The dissolution behaviour of budesonide/gamma-CD complexes was dependent on their crystal structure: the tetragonal form dissolved faster than the hexagonal form.

CONCLUSIONS

The crystal structure of gamma-CD and subsequently, the dissolution rate of complexed budesonide, can be modified with the processing conditions.

[Factors influencing the content of residual tert-butyl alcohol in cyclodextrin complex prepared by lyophilization cosolvent system]

In order to minimize the residual tert-butyl alcohol (TBA) level in cyclodextrin complex prepared by freeze drying TBA/water cosolvent system, the formulation and lyophilization procedure that may influence the residual TBA was studied. Residual TBA in freeze dried cyclodextrin complex was determined by gas chromatography. The significant formulation and processing factors that influence residual TBA were identified by adjusting the initial TBA concentration in cosolvent, selecting cyclodextrin type (beta-cyclodextrin or hydroxypropyl beta-cyclodextrin), changing sample volume in flasket, altering freezing mode (fast freezing or slow freezing) and modifying the duration of secondary drying. The results show that the amorphous cyclodextrin material (hydroxypropyl beta-cyclodextrin), initial low TBA concentration in cosolvent and fast freezing would lead to high TBA residue in cyclodextrin complex, annealing was effective in reducing the residual TBA. The duration of secondary drying had no distinct effect on residual TBA. It is concluded that in order to reduce residual TBA in cyclodextrin complex prepared by lyophilization monophase solution, the initial TBA concentration in cosolvent should be higher than the crystal formation concentration, the appropriate cyclodextrin type and freeze drying processing should be choosen.

Chitosan-based controlled porosity osmotic pump for colon-specific delivery system: Screening of formulation variables and in vitro investigation

A microbially triggered colon-targeted osmotic pump (MTCT-OP) has been studied. The gelable property at acid condition and colon-specific biodegradation of chitosan were used to: (1) produce the osmotic pressure, (2) form the drug suspension and (3) form the in situ delivery pores for colon-specific drug release, respectively. The scanning electron microscopy (SEM) study and the calculation of membrane permeability were applied to elucidate the mechanism of MTCT-OP. The effects of different formulation variables, including the level of pH-regulating excipient (citric acid) and the amount of chitosan in the core, the weight gain of semipermeable membrane and enteric-coating membrane, and the level of pore former (chitosan) in the semipermeable membrane, have been studied. Results of SEM showed that the in situ delivery pores could be formed in predetermined time after coming into contact with dissolution medium, and the number of pore was dependent on the initial level of pore former in the membrane. The amount of budesonide release was directly proportional to the initial level of pore former, but inversely related to the weight of semipermeable membrane. The effects of variations in the level of citric acid and chitosan in the core formulation on drug release were studied. The different levels of enteric-coating membrane could prevent cellulose acetate membrane (containing chitosan as pore former) from forming pore or rupture before contact with simulated colonic fluid, but had no effect on the drug release. Budesonide release from the developed formulation was inversely proportional to the osmotic pressure of the release medium, confirming that osmotic pumping was the major mechanism of drug release. These results showed that MTCT-OP based on osmotic technology and microbially triggered mechanism had a high potential for colon-specific drug delivery.

[Preparation of budesonide-poly (ethylene oxide) solid dispersions using supercritical carbon dioxide and in vitro evaluation]

An application of supercritical fluids technology for processing of budesonide-poly (ethylene oxide) solid dispersions was presented. The correlations of the operation parameters in the preparation process were studied. Solid dispersions of budesonide in poly (ethylene oxide) were prepared using a static method for supercritical carbon dioxide and characterized by powder X-ray diffractometry, differential scanning calorimetry, intrinsic dissolution, and in vitro dissolution. It was found that the optimum condition of solid dispersions formation was as follows: temperature, 40 degrees C ; pressure, 20 MPa; the ratio of budesonide and poly (ethylene oxide) , 1: 10. Drug existed in amorphous state in hydrophilic poly (ethylene oxide) carriers and intrinsic solubility and dissolution rates were significantly enhanced. The mechanism of the enhanced dissolution may be attributed to the amorphous character of the budesonide, improvement of the wettability of the hydrophobic budesonide, together with the formation of hydrogen bond of budesonide and hydrophilic poly (ethylene oxide). The supercritical fluids process can be used as an alternative method for preparation of solid dispersions.

The effect of carrier surface treatment on drug particle detachment from crystalline carriers in adhesive mixtures for inhalation

In this study, the effect of lactose carrier surface treatment on drug particle detachment during inhalation has been investigated. Crystals of marketed brands of alpha lactose monohydrate brands normally exhibit a certain surface rugosity and contain natural fines and impurities on their surface, which influence the drug-to-carrier interaction in adhesive mixtures for inhalation. Submersion treatment may change these surface characteristics. Two different sieve fractions (63-90 and 250-355microm) were submerged in mixtures of ethanol and water (96 and 80% v/v, respectively). Microscopic observation and laser diffraction analysis revealed that neither the shape nor the size of the carrier particles was changed by the submersion treatment. However, the specific surface area and the amount of impurities appeared to decrease substantially after submersion, and the magnitude of the decrease was different for the different ethanol-water mixtures. The reduction in specific surface area was attributed particularly to the removal of the adhering lactose fines from the carrier surface. Mixtures with budesonide (in a wide range of carrier payloads) were prepared before and after treatment. Drug particle detachment from the various mixtures was studied with a sieve test and with a cascade impactor analysis at 30 and 60l/min. Two different types of inhalers were used, one generating lift- and drag-forces (ISF inhaler) and one generating inertial forces (test inhaler), respectively. The cascade impactor and sieve test experiments showed that an increase in carrier surface smoothness results in a reduced drug particle detachment during inhalation, which was independent of the type of inhaler used. This reduction could be attributed to the removal of the adhering lactose fines which may provide shelter for the drug particles from press-on forces during mixing.

In vitro investigation of drug particulates interactions and aerosol performance of pressurised metered dose inhalers

PURPOSE

To determine a relationship between adhesive and cohesive inter-particulate forces of interactions and in vitro performance in pressurised metered dose inhalers (pMDIs) suspension formulations.

METHODS

Interparticulate forces of salbutamol sulphate (SS), budesonide (BUD) and formoterol fumarate dihydrate (FFD) were investigated by in situ atomic force microscopy (AFM) in a model propellant 2H, 3H perfluoropentane (HPFP). Experimental data were analysed using the recently developed cohesive/adhesive analysis method (CAB) and compared with in vitro deposition performances in pMDIs systems using Andersen cascade impactor (ACI).

RESULTS

The in vitro investigation suggested that the micronised drug materials had significantly different aerosolisation profiles when manufactured as single or combination formulations. In general, the greatest significant differences were observed between SS single drug and SS-BUD and SS-FFD combinations. Analysis of the in vitro performance for the SS only formulation suggested that the cohesive nature of SS (as predicted by the CAB and observed with AFM) led to tightly bound flocs that did not fully deaggregate upon aerosolisation.

CONCLUSIONS

It is suggested that the relationship between interparticulate interactions and in vitro performance of pMDIs suspension systems, when compared to direct measurement of the adhesion/cohesion forces, indicated good correlation. This approach may be useful in expediting the development of pMDI formulation and predicting performance.

Preparation of budesonide/γ‐cyclodextrin complexes in supercritical fluids with a novel SEDS method

The aim was to investigate if solid drug/cyclodextrin complexes could be produced in a single-step process with a solution enhanced dispersion by supercritical fluids (SEDS) method. Budesonide and gamma-cyclodextrin (CD) solutions (50% or 99.5% ethanol) were pumped from the same (conventional method) or separate (modified method) containers together with supercritical carbon dioxide through a coaxial nozzle into a particle formation chamber. The pressure was maintained at 100, 150 or 200 bar with a temperature of 40, 60 or 80 degrees C. SEDS-processed powders were characterised with HPLC, DSC and XRPD for budesonide content, complexation and crystallinity. The budesonide dissolution rate was determined in 1% gamma-CD aqueous solution. Solid, white budesonide/gamma-CD complex particles were formed using the conventional and modified SEDS processes. The complexation efficiency was dependent on the processing conditions. For example, with the conventional method (100 bar, 60 degrees C) the yield of the powder was 65+/-12% with 0.14+/-0.02 mg budesonide/mg powder, corresponding to 1:2 drug:CD molar ratio. The dissolution rate of this complexed budesonide (93+/-2% after 15 min) was markedly higher compared to unprocessed micronised budesonide (41+/-10%) and SEDS-processed budesonide without CD (61+/-3%). As a conclusion, SEDS is a novel method to produce solid drug/CD complexes in a single-step process.

Pharmacoscintigraphic evaluation of lipid dry powder budesonide formulations for inhalation

Lung deposition of new formulations of budesonide, using solid lipid microparticles (SLmP) as a pharmaceutically acceptable filler and carrier for inhalation aerosols, and administered from a dry powder inhaler (Cyclohaler), were compared with that from Pulmicort Turbuhaler. Six healthy volunteers took part in a three-way randomized cross-over study, and inhaled a nominal dose of 400 microg budesonide, labelled with 99mTc, on each study day. Lung deposition was determined by gamma scintigraphy and by a pharmacokinetic method. The percentage of dose (SD) in the whole lung was 49.9 (3.7)% for the lipidic matricial form (M) and 62.8 (4.9)% for the lipidic physical blend formulation (PB). These results corresponded well with the in vitro fine particle assessment. In comparison with data recorded in literature for in vivo deposition obtained with Pulmicort Turbuhaler, it was estimated that lung deposition was 1.5 and 2.0 times higher for the M and PB formulations, respectively. Furthermore, the relative drug availability obtained from the pharmacokinetic evaluation, expressed as the percentage of pulmonary absorption of the comparator product, was 154% and 220% for M and PB, respectively. The results of the present study indicate that pulmonary administration using SLmP gives a prominent and significant increase in budesonide lung deposition.

Detection of budesonide in human urine after inhalation by liquid chromatography-mass spectrometry

Budesonide, a corticosteroid frequently used in the treatment of asthma, is most often administered via inhalation. Its use in sports is allowed when medically necessary. A fast, sensitive and accurate LC-MS method was developed and validated for the quantification of budesonide and its major metabolite 16alpha-hydroxyprednisolone in urine samples after inhalation of a metered dose (Pulmicort-Turbohaler 200). Sample preparation consists of an alkaline liquid-liquid extraction with ethyl acetate. Analysis was performed using liquid chromatography-tandem mass spectrometry with electrospray ionization (ESI). The method was linear in the range of 5-100 and 0.5-10ng/mL for 16alpha-hydroxyprednisolone and budesonide, respectively. The limits of quantification were 5ng/ml for 16alpha-hydroxyprednisolone and 0.5ng/mL for budesonide. The accuracy ranged from 2.2 to 3.5% for 16alpha-hydroxyprednisolone and from 0.8 to 16.4% for budesonide. After administration of 200microg of budesonide to five healthy volunteers budesonide could not be detected in any urine sample whereas 16alpha-hydroxyprednisolone was detectable up to 12h post-administration.