In vivo-in vitro comparison of deposition in three mouth-throat models with Qvar and Turbuhaler inhalers.

In vitro polydisperse aerosol deposition in three mouth-throat models, namely, the USP (United States Pharmacopeia) mouth-throat (induction port), idealized mouth-throat, and highly idealized mouth-throat, was investigated experimentally. Aerosol particles emitted from two commercial inhalers, Qvar (pMDI) and Turbuhaler (DPI), were used. The in vitro deposition results in these three mouth-throat models were compared with in vivo data available from the literature. For the DPI, mouth-throat deposition was 57.3 +/- 4.5% for the USP mouth-throat, 67.8 +/- 2.2% for the idealized mouth-throat, and 69.3 +/- 1.1% for the highly idealized mouth-throat, which are all relatively close to the in vivo value of 65.8 +/- 10.1%. In contrast, for the pMDI, aerosol deposition in the idealized mouth-throat (25.8 +/- 4.2%) and the highly idealized mouth-throat (24.9 +/- 2.8%) agrees with the in vivo data (29.0 +/- 18.0%) reported in the literature better than that for the USP mouth-throat (12.2 +/- 2.7%). In both cases, the USP mouth-throat gives the lowest deposition among the three mouth-throat models studied. In summary, both the idealized mouth-throat and highly idealized mouth-throat improve the accuracy of predicted mean in vivo deposition in the mouth-throat region. This result hints at the potential applicability of either the idealized mouth-throat or highly idealized mouth-throat as a future USP mouth-throat standard to provide mean value prediction of in vivo mouth-throat deposition.     

Deposition of corticosteroid aerosol in the human lung by Respimat Soft Mist inhaler compared to deposition by metered dose inhaler or by Turbuhaler dry powder inhaler.

Fourteen mild-to-moderate asthmatic patients completed a randomized four-way crossover scintigraphic study to determine the lung deposition of 200 microg budesonide inhaled from a Respimat Soft Mist Inhaler (Respimat SMI), 200 microg budesonide inhaled from a Turbuhaler dry powder inhaler (Turbuhaler DPI, used with fast and slow peak inhaled flow rates), and 250 microg beclomethasone dipropionate inhaled from a pressurized metered dose inhaler (Becloforte pMDI). Mean (range) whole lung deposition of drug from the Respimat SMI (51.6 [46-57]% of the metered dose) was significantly (p < 0.001) greater than that from the Turbuhaler DPI used with both fast and slow inhaled flow rates (28.5 [24-33]% and 17.8 [14-22]%, respectively) or from the Becloforte pMDI (8.9 [6-12]%). The deposition pattern within the lungs was more peripheral for Respimat SMI than for Turbuhaler DPI. The results of this study showed that Respimat SMI deposited corticosteroid more efficiently in the lungs than either of two widely used inhaler devices, Turbuhaler DPI or Becloforte pMDI.     

Characterisation and functionality of inhalation anhydrous lactose

The relationships between the physicochemical properties and functionality in dry powder inhaler (DPI) performance was investigated for inhalation grade anhydrous lactose and compared to monohydrate grades. The excipients were characterised using a range of techniques including particle size analysis, moisture sorption and powder rheometry. The inhalation anhydrous lactose grades were readily characterisable. The aerosolisation performance of capsule based DPI formulations containing budesonide (200 μg) and different grades of lactose evaluated using inertial impaction measurements produced fine particle doses of budesonide ranging from 24 to 49 μg. There were no apparent relationships between aerosolisation performance and excipient characteristics, such as particle size and powder density. However, formulations containing lactose grades which exhibit higher powder fluidisation energy values resulted in higher fine particle doses of budesonide.     

In vitro monodisperse aerosol deposition in a mouth and throat with six different inhalation devices.

Experiments were performed to determine the effect of different pharmaceutical aerosol inhalation devices on the deposition of monodisperse aerosols in an idealized mouth and throat geometry. The devices included two dry powder inhalers (Diskus and Turbuhaler), two nebulizers (Pari LC STAR and Hudson T-Updraft), and a metered dose inhaler with attached holding chamber (Aerochamber), in addition to a straight tube (1.7 cm inner diameter). Aerosol particles (DL-alpha tocopheryl acetate) of diameters of 2.5, 5, and 7 microm generated by a vibrating orifice generator were inhaled at steady air flow rates of Q = 5-90 L/min through the devices and into the mouth-throat. Deposition in the mouth-throat and after-filter were determined by ultraviolet (UV) spectrophotometric assay. The amount of deposition in the mouth and throat region was found to depend on the type of device that the aerosol entered through. Deposition in the extrathoracic region with the two types of jet nebulizers did not differ significantly (p > 0.1) from that of a straight tube or each other over their entire tested range of 590 > or = pd2Q > or = 11,375, where p is particle density (in g/cm3), d is particle diameter (in microm), and Q is flow rate (in cm3/s). The metered dose inhaler with attached holding chamber was found to differ from the straight tube only at two intermediate values of pd2Q = 5,145 and 16,033. The deposition occurring for the dry powder inhalers was found to be significantly greater than for the straight tube for all values of pd2Q > or = 10,954 for the Diskus and pd2Q > or = 9,435 for the Turbuhaler. Deposition with the dry powder inhalers was found to be up to 14 times greater than that with the straight tube. Thus, the inhaler geometry that the aerosol passes through prior to entering the mouth and throat region can greatly affect the deposition in the mouth-throat.     

Drug delivery from the Turbuhaler and Nebuhaler pressurized metered dose inhaler to various age groups of children with asthma.

A total of 198 children aged 3 to 15 years inhaled a single dose of 200 micrograms budesonide from a Nebuhaler pressurized metered dose inhaler (pMDI) and a Turbuhaler dry powder inhaler in a randomized crossover study. The budesonide dose delivered to a patient was assessed by measuring the amount of drug deposited on a filter inserted between the inhaler outlet and the patient's mouth. The dose of budesonide deposited on the filter and the estimated dose of particles with a mass median aerodynamic diameter (MMAD) of 5 microns or less after inhalation from the Turbuhaler were both approximately twice the values inhaled from the pMDI Nebuhaler in children less than 5 years of age (P < 0.01). The variation in the dose delivered to the patient was similar for the two inhalers in children over 5 years old. In 3- to 4-year-old children, dose delivery to the patient was higher and/or more consistent from the pMDI Nebuhaler than from the Turbuhaler. Filter dose after Turbuhaler treatment varied significantly from peak inspiratory flow rate through the Turbuhaler (PIFTbh) (P < 0.01). The percentage of children producing a PIFTbh greater than 50 L/min decreased with age (89%, 45%, and 14% in 5-, 4-, and 3-year-old children, respectively). It is concluded that drug delivery to a child with asthma varies with age and inhalation device. Further studies are needed to assess the clinical importance of this finding.     

Lactose modifications enhance its drug performance in the novel multiple dose Taifun DPI

Drug–carrier particle interactions greatly affect the detachment of drug from the carrier in inhalation powders. In this study, a novel multiple dose, reservoir-based Taifun^® was used as a dry powder inhaler, and the effects of carrier physical properties were evaluated on the pulmonary deposition of budesonide, along with physical stability of the inhalation powder. In this study, untreated commercial preparation of -lactose monohydrate, highly amorphous spray dried lactose, crystallized spray dried lactose, Flowlac-100^® and Flowlac-100^® mixed with crystalline micronized lactose were used as carriers. Dry powder formulations were prepared by the suspension method, where the budesonide–carrier ratio was 1:15.1 (w/w). Carriers and formulations were initially characterized, and again after 1 month’s storage at 40 °C/75% RH. The physical properties of the carriers strongly affected the pulmonary deposition of budesonide and the physical stability of the inhalation powder. Initially, amorphous contents of the carriers were 0–64%, but spontaneous crystallisation of the amorphous lactose occurred during storage and, thus all carriers were 100% crystalline after storage. When compared to an untreated -lactose monohydrate, the highly amorphous spray dried lactose and Flowlac-100^® did not improve aerosol performance of the inhalation powder. When crystalline spray dried lactose was used as a carrier, the highest RF% values were achieved, and RF % values did not alter during storage but the emitted budesonide dose was lower than the theoretical dose. When Flowlac-100^® mixed with crystalline micronized lactose was used as a carrier, the emitted budesonide dose was close to the theoretical dose, and high RF % values were achieved but these changed during storage.     

Preparation and in vitro evaluation of lipidic carriers and fillers for inhalation.

The present study relates to compositions of solid lipidic microparticles (SLmP), composed of biocompatible phospholipids and cholesterol, and their use as carriers or as fillers delivering drugs directly to the lungs via a dry powder inhaler (DPI). SLmP were obtained by spray-drying and were formulated as lipidic matrices entrapping budesonide or as physical blends (drug carrier). They were developed in order to improve the delivery of the active drug by the pulmonary route. The SLmP were evaluated for their physical characteristics and in vitro deposition measurements were performed using the Multi-stage Liquid Impinger (MsLI). The Pulmicort Turbuhaler DPI (AstraZeneca) was used as a comparator product. The SLmP appeared to be spherical low-density material characterized by a smooth surface. The mass median diameters (D(0.5)), and the volume mean diameters (D[4,3]) were tiny and ranged from 1.7 to 3.1 microm and from 2.0 to 3.9 microm, respectively. The SLmP formulations, delivered by the Cyclohaler inhaler, were found to emit a fine particle dose (FPD) of 93-113 microg, which is very promising comparing to the FPD (68 microg) delivered by the Pulmicort Turbuhaler.     

Lactose characteristics and the generation of the aerosol

The delivery efficiency of dry-powder products for inhalation is dependent upon the drug formulation, the inhaler device, and the inhalation technique. Dry powder formulations are generally produced by mixing the micronised drug particles with larger carrier particles. These carrier particles are commonly lactose. The aerosol performance of a powder is highly dependent on the lactose characteristics, such as particle size distribution and shape and surface properties. Because lactose is the main component in these formulations, its selection is a crucial determinant of drug deposition into the lung, as interparticle forces may be affected by the carrier-particle properties. Therefore, the purpose of this article is to review the various grades of lactose, their production, and the methods of their characterisation. The origin of their adhesive and cohesive forces and their influence on aerosol generation are described, and the impact of the physicochemical properties of lactose on carrier-drug dispersion is discussed in detail.     

Clinical pharmacokinetics of inhaled budesonide

The corticosteroid budesonide is a 1:1 racemic mixture of 2 epimers, (22R)- and (22S)-, and is available in 3 different inhaled formulations for the management of asthma: a pressurised metered dose inhaler (pMDI), a dry powder inhaler (DPI) and a solution for nebulised therapy. Inhaled corticosteroids such as budesonide reach the systemic circulation either by direct absorption through the lungs (a route that is much more important than previously recognised) or via gastrointestinal absorption of drug that is inadvertently swallowed. Although the pharmacokinetics of budesonide have been extensively investigated following oral and intravenous administration, relatively few studies have defined the systemic disposition of budesonide after inhalation. Drug deposition in the lungs depends on the inhaler device: 15% of the metered dose of budesonide reached the lung with a pMDI compared with 32% with a breath-actuated DPI. In patients with asthma (n = 38) receiving different doses of budesonide by DPI (Turbuhaler), the pharmacokinetic parameters peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) were dose-dependent after both single dose and repeat dose (3 weeks) administration: time to Cmax (tmax) was short (0.28 to 0.40 hours) and the elimination half-life approximately 3 hours. Both AUC and Cmax were linearly related to budesonide dose. In a small group of healthy male volunteers (n = 9), the pharmacokinetics of budesonide 1,600 microg twice daily via pMDI were assessed on the fifth day of administration. Mean model-independent parameters for (22R)-budesonide were as follows: Cmax 1.8 microg/L, tmax 0.46 hours, elimination half-life 2.3 hours and oral clearance 163 L/h, and there were no enantiomer-specific differences in drug disposition. Budesonide undergoes fatty acid conjugation within the lung, but very limited pharmacokinetic data are available to define the pulmonary absorption characteristics. There is evidence from a population analysis that the pulmonary absorption of budesonide is prolonged and shows wide interindividual variation. Further pharmacokinetic studies are required to define the time-course of budesonide absorption through the lung in specific patient groups, and to investigate the effect of new inhaler devices (especially chlorofluorocarbon-free pMDIs) on the pharmacokinetic profile and systemic drug exposure.     

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.     

Applicability of DPI formulations for novel neurokinin receptor antagonist

A novel triple neurokinin receptor antagonist (TNRA) could have pharmaceutical efficacy for asthma and/or chronic obstructive pulmonary disease. TNRA is potentially developed as inhalation medicine. The aim of this investigation was to evaluate the applicability of dry powder inhaler (DPI) formulation for TNRA. DPI formulation containing lactose was used for this feasibility study. Mechanofusion process for surface modification was applied on lactose particles to prepare four different DPI formulations. The mixture of TNRA and lactose was administered to rats intratracheally using an insufflator. The deposition pattern and blood concentration profile of TNRA were evaluated. Although there was no significant difference in deposition on deep lungs between the four formulations, DPI formulations containing mechanofusion-processed lactose showed longer T(max) and t(1/2) and higher AUC(0-infinity) and MRT compared to that containing intact lactose. On the other hand, the contact angle measurement showed that the mechanofusion process decreased the polar part of the surface energy of the lactose. Therefore, the prolongation of the wetting of the formulated powder mixture seemed to delay the dissolution of TNRA deposited in respiratory tract. It was concluded that DPI formulation containing mechanofusion-processed lactose could be suitable for inhalation of TNRA.     

Airmax: a multi-dose dry powder inhaler

Airmax is a multi-dose dry powder inhaler. An internal pump measures out the drug dose using controlled air pressure. Inhalation transports the drug into a cyclone separator (where active drug is separated from the lactose carrier) and then into the patient airway. In vitro studies indicate that Airmax may be less dependent on airflow than Turbuhaler for drug delivery; greater dose consistency was seen with administration of budesonide via Airmax than via Turbuhaler. At a low flow rate, the lung deposition of budesonide administered via Airmax was greater than that of budesonide administered via Turbuhaler or a pressurised metered dose inhaler in patients with asthma. In cumulative-dose studies, the mean forced expiratory volume in 1 second (FEV(1)) achieved with salbutamol (albuterol) or formoterol administered via Airmax was equivalent to that achieved with twice the dose administered via dry powder inhalers. black triangle In randomised, double-blind studies, budesonide administration via Airmax was equivalent to administration via Turbuhaler with regards to FEV(1) and improvement in asthma symptoms in both adults and children with asthma. The concentration of adenosine monophosphate producing a 20% fall in FEV(1) increased from pretreatment levels by a greater extent with budesonide administered via Airmax, compared with Turbuhaler. Both adults and children preferred Airmax to Turbuhaler, and more found Airmax easier to use. In one study, the majority of children found learning how to use Airmax trade mark easier than learning how to use Turbuhaler.     

SCF-engineered powders for delivery of budesonide from passive DPI devices

The objective of this study was to develop SEDS-engineered budesonide particles suitable for dry powder inhalation delivery and to evaluate their aerosol performance across a range of passive dry powder inhalers (DPI). SEDS budesonide powders were manufactured in Nektar's SCF manufacturing plant and compared to the micronized drug and commercial powder (Pulmicort Turbuhaler, AstraZeneca). Aerosol performance was evaluated by determining emitted dose (ED) by a variation of the USP method and fine particle fraction (FPF) using Andersen cascade impaction. The SCF powder dispersed best in the Turbospin and Eclipse devices, exhibiting high EDs (70%-80%) and relatively low variability (RSD 8%-13%). Regardless of the device, the SEDS material outperformed both the micronized drug and the commercial powder, while exhibiting good batch-to-batch reproducibility (RSD <5%). All powders exhibited flow rate-dependent ED, albeit for the SEDS material it was minimized at reduced fill weights. This was attributed to inadequate and variable powder clearance from the capsules at low inspiratory flow rates, which was more pronounced in the Eclipse and Cyclohaler. The results demonstrate that SEDS is an attractive particle-engineering process that may enhance pulmonary performance of budesonide and possibly facilitate development of other small molecule pulmonary products in passive DPI.     

Physico-chemical aspects of lactose for inhalation

A dry powder inhaler (DPI) is a dosage form that consists of a powder formulation in a device which is designed to deliver an active ingredient to the respiratory tract. It has been extensively investigated over the past years and several aspects relating to device and particulate delivery mechanisms have been the focal points for debate. DPI formulations may or may not contain carrier particles but whenever a carrier is included in a commercial formulation, it is almost invariably lactose monohydrate. Many physicochemical properties of the lactose carrier particles have been reported to affect the efficiency of a DPI. A number of preparation methods have been developed which have been claimed to produce lactose carriers with characteristics which lead to improved deposition. Alongside these developments, a number of characterization methods have been developed which have been reported to be useful in the measurement of key properties of the particulate ingredients. This review describes the various physicochemical characteristics of lactose, methods of manufacturing lactose particulates and their characterization.     

Design and application of a new modular adapter for laser diffraction characterization of inhalation aerosols

An inhaler adapter has been designed for the characterization of the aerosol clouds from medical aerosol generators such as nebulizers, dry powder inhalers (dpis) and metered dose inhalers (mdis) with laser diffraction technology. The adapter has a pre-separator, for separation of large particles (i.e. carrier crystals) from the aerosol cloud before it is exposed to the laser beam. It also has a fine particle collector for measuring the emitted mass fraction of fines by chemical detection methods after laser diffraction sizing. The closed system enables flow control through the aerosol generators and all test conditions, including ambient temperature and relative humidity, are automatically recorded. Counter flows minimize particle deposition onto the two windows for the laser beam, which make successive measurements without cleaning of these windows possible. The adapter has successfully been tested for nebulizers, mdis and dpis. In a comparative study with ten nebulizers it was found that these devices differ considerably in droplet size (distribution) of the aerosol cloud for the same 10% aqueous tobramycin solution (volume median diameters ranging from 1.25 to 3.25 microm) when they are used under the conditions recommended by the manufacturers. The droplet size distribution generated by the Sidestream (with PortaNeb compressor) is very constant during nebulization until dry running of the device. Comparative testing of dpis containing spherical pellet type of formulations for the drug (e.g. the AstraZeneca Turbuhaler) with the adapter is fast and simple. But also formulations containing larger carrier material could successfully be measured. Disintegration efficiency of a test inhaler with carrier retainment (acting as a pre-separator) could be measured quite accurately both for a colistin sulfate formulation with 16.7% of a lactose fraction 106-150 microm and for a budesonide formulation with a carrier mixture of Pharmatose 325 and 150 M. Therefore, it is concluded that, with this special adapter, laser diffraction may be a valuable tool for comparative inhaler evaluation, device development, powder formulation and quality control. Compared to cascade impactor analysis, laser diffraction is much faster. In addition to that, more detailed and also different information about the aerosol cloud is obtained.     

影响干粉吸入剂雾化和沉积性能的制剂因素

干粉吸入剂是近年来肺部给药制剂研发的热点。随着微粉化技术不断成熟,新型给药装置日益涌现,干粉吸入剂的应用范围越来越广。本文从微粉化的药物、载体和干粉吸入器等3个方面综述了干粉吸入剂的处方组成,并重点介绍了影响药物粉末雾化和沉积性能的几个关键因素。     

The influence of orally deposited budesonide on the systemic availability of budesonide after inhalation from a Turbuhaler.

1. The aim of this pharmacokinetic study was to evaluate to what extent oropharyngeal deposition of drug contributes to the systemic availability of budesonide inhaled from a dry powder inhaler (Turbuhaler). 2. The design was a randomized cross-over study in eight children aged 7-13 years. The plasma concentrations of the two epimers of budesonide (22R and 22S) after inhalation of 1 mg budesonide from a Turbuhaler were compared with the plasma concentrations obtained when the absorption of the drug deposited in the oropharynx was blocked by drinking and rinsing the mouth with charcoal before and after the inhalation. 3. The plasma concentrations of budesonide were significantly reduced by the charcoal treatment (P < 0.01) and the area under the time vs plasma concentration curve 0-4 h was significantly reduced from 9.5 to 8.0 mmol l-1 h for 22S (P < 0.01) and from 7.6 to 5.7 mmol l-1 h for 22R (P < 0.01). 4. The plasma concentrations and the AUCs after both Turbuhaler administrations were markedly higher than those obtained in earlier studies using other inhalers suggesting a higher intrapulmonary deposition of drug after Turbuhaler treatment. 5. It is concluded that oropharyngeal deposition of drug accounts for about 20% of the total systemic availability of budesonide inhaled from Turbuhaler. Thus, the main contribution to the system comes from budesonide absorbed in the airways.     

Novolizer: how does it fit into inhalation therapy?

Inhalation therapy is the preferred route of administration of anti-asthmatic drugs to the lungs. However, the vast majority of patients cannot use their inhalers correctly, particularly pressurised metered dose inhalers (pMDIs). The actual proportion of patients who do not use their inhalers correctly may even be under-estimated as GPs tend to over-estimate correct inhalation technique. Dry powder inhalers (DPIs) have many advantages over pMDIs. Unlike pMDIs, they are environmentally-friendly, contain no propellant gases and, more importantly, they are breath-activated, so that the patient does not need to coordinate actuation of the inhaler with inspiration. Three key parameters for correct inhaler use should be considered when evaluating existing or future DPI devices and especially when choosing the appropriate device for the patient: (1) usability, (2) particle size distribution of the emitted drug and (3) intrinsic airflow resistance of the device. The Novolizer is a breath-activated, multidose, refillable DPI. It is easy to use correctly, has multiple feedback and control mechanisms which guide the patient through the correct inhalation manoeuvre. In addition, the Novolizer has an intelligent dose counter, which resets only after a correct inhalation and may help to monitor patient compliance. The Novolizer has a comparable or better lung deposition than the Turbuhaler at similar or higher peak inspiratory flow (PIF) rates. A flow trigger valve system ensures a clinically effective fine particle fraction (FPF) and sufficient drug delivery, which is important for a good lung deposition. The FPF produced through the Novolizer is also relatively independent of flow rate and the device shows better reproducibility of metering and delivery performance compared to the Turbuhaler. The low-to-medium airflow resistance means that the Novolizer is easy for patients to use correctly. Even children, patients with severe asthma and patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) have no problems to generate the trigger inspiratory flow rate required to activate the Novolizer. The Novolizer uses an advanced DPI technology and may improve patient compliance.     

Evaluation of SCF-engineered particle-based lactose blends in passive dry powder inhalers

The objective of this study was to assess the performance of SCF-engineered budesonide and albuterol sulfate powder blends in passive dry powder inhalers (DPI) relative to micronized drug blends. A number of lactose grades for inhalation were screened and the appropriate carrier and drug-to-lactose blending ratio were selected based on drug content and emitted dose uniformity. Aerosol performance was characterized by Andersen cascade impaction. Blend formulations of SEDS (solution enhanced dispersion by supercritical fluids) budesonide and albuterol exhibited a significant drug content uniformity (7-9% RSD) improvement over micronized drug blends (16-20% RSD). Further, the SEDS formulations demonstrated higher emitted dose and reduced emitted dose variability (10-12% RSD) compared to micronized powders (21-25% RSD) in the Turbospin, albeit without significant enhancement of the fine particle fraction. In contrast, SEDS powders exhibited increased fine particle fractions over micronized blends in the Clickhaler; improvements were more pronounced with albuterol sulfate. The performance enhancements observed with the SEDS powders are attributed to their increased surface smoothness and reduced surface energy that are presumed to minimize irreversible drug-carrier particle interactions, thus resulting in more efficient drug detachment from the carrier particle surface during aerosolization. As demonstrated for budesonide and albuterol, SEDS may enhance performance of lactose blends and thus provide an attractive particle engineering option for the development of blend formulations for inhalation delivery.     

Influence of primary crystallisation conditions on the mechanical and interfacial properties of micronised budesonide for dry powder inhalation

Investigate the influence of primary crystallisation conditions on the mechanical properties and secondary processing behaviour of budesonide for dry powder inhaler (DPI) formulations. Young's modulus of two batches of budesonide crystals (samples A and B) produced using different anti-solvents was determined using nanoindentation. Physicochemical and surface interfacial properties via the cohesive-adhesive balance (CAB) approach to colloid probe atomic force microscopy (AFM) of air-jet micronised budesonide crystals were also investigated. These data were correlated to in vitro aerosolization performance of carrier-based DPI formulations containing either budesonide samples A or B and lactose monohydrate. Young's modulus of budesonide samples A and B crystals was 0.95 and 4.04 GPa, respectively. Sample A crystals with low Young's modulus exhibited poorer micronisation efficiency than sample B. CAB analysis of micronised budesonide samples A and B, suggest that sample B budesonide had a greater adhesion to lactose than sample A. These data correlated with in vitro aerosolisation studies, which showed that the fine particle delivery of budesonide sample A was higher than that of sample B. In conclusion, crystallisation conditions may affect the mechanical properties of budesonide, and therefore secondary processing of the material and their interfacial properties and product performance in carrier based DPI formulations.