Micronization of anti-inflammatory drugs for pulmonary delivery by a controlled crystallization process

Developing Dry Powder Inhaler Formulations

This section aims to provide a concise and contemporary technical perspective and reference resource covering dry powder inhaler (DPI) formulations. While DPI products are currently the leading inhaled products in terms of sales value, a number of confounding perspectives are presented to illustrate why they are considered surprisingly, and often frustratingly, poorly understood on a fundamental scientific level, and most challenging to design from first principles. At the core of this issue is the immense complexity of fine cohesive powder systems. This review emphasizes that the difficulty of successful DPI product development should not be underestimated and is best achieved with a well-coordinated team who respect the challenges and who work in parallel on device and formulation and with an appreciation of the handling environment faced by the patient. The general different DPI formulation types, which have evolved to address the challenges of aerosolizing fine cohesive drug-containing particles to create consistent and effective DPI products, are described. This section reviews the range of particle engineering processes that may produce micron-sized drug-containing particles and their subsequent assembly as either carrier-based or carrier-free compositions. The creation of such formulations is then discussed in the context of the material, bulk, interfacial and ultimately drug-delivery properties that are considered to affect formulation performance. A brief conclusion then considers the future DPI product choices, notably the issue of technology versus affordability in the evolving inhaler market.

Antisolvent Crystallization of Telmisartan Using Stainless-Steel Micromixing Membrane Contactors

Controlled continuous crystallization of the active pharmaceutical ingredient (API) telmisartan (TEL) has been conducted from TEL/DMSO solutions by antisolvent crystallization in deionized water using membrane micromixing contactors. The purpose of this work was to test stainless-steel membranes with ordered 10 μm pores spaced at 200 μm in a stirred-cell (batch, LDC-1) and crossflow (continuous, AXF-1) system for TEL formation. By controlling the feed flow rate of the API and solvent, through the membrane pores as well as the antisolvent flow, it was possible to tightly control the micromixing and with that to control the crystal nucleation and growth. Batch crystallization without the membrane resulted in an inhomogeneous crystallization process, giving a mixture of crystalline and amorphous TEL materials. The rate of crystallization was controlled with a higher DMSO content (4:1 DMSO/DI water), resulting in slower crystallization of the TEL material. Both membrane setups, stirred batch and the crossflow, yielded the amorphous TEL particles when deionized water was used, while a crystalline material was produced when a mixture of DI water and DMSO was used.

Optimization of Spray Drying Process Parameters for the Preparation of Inhalable Mannitol-Based Microparticles Using a Box-Behnken Experimental Design

Inhalation is used for local therapy of the lungs and as an alternative route for systemic drug delivery. Modern powder inhalation systems try to target the required site of action/absorption in the respiratory tract. Large porous particles (LPPs) with a size >5 μm and a low mass density (usually measured as bulk or tapped) of <0.4 g/cm³ can avoid protective lung mechanisms. Their suitable aerodynamic properties make them perspective formulations for deep lung deposition. This experiment studied the effect of spray-drying process parameters on LPP properties. An experimental design of twelve experiments with a central point was realized using the Box-Behnken method. Three process parameters (drying temperature, pump speed, and air speed) were combined on three levels. Particles were formed from a D-mannitol solution, representing a perspective material for lung microparticles. The microparticles were characterized in terms of physical size (laser diffraction), aerodynamic diameter (aerodynamic particle sizer), morphology (SEM), and densities. The novelty and main goal of this research were to describe how the complex parameters of the spray-drying process affect the properties of mannitol LPPs. New findings can provide valuable data to other researchers, leading to the easy tuning of the properties of spray-dried particles by changing the process setup.

Engineered mucoadhesive microparticles of formoterol/budesonide for pulmonary administration

In the present study, a multi-component system comprised of dipalmitylphospatidylcholine (DPPC), Chitosan, Lactose, and L-Leucine was developed for pulmonary delivery. Microparticles were engineered by the spray drying process and the selection of the critical parameters was performed by applying experimental design. The microcarriers with the appropriate size and yield were co-formulated with two active pharmaceutical ingredients (APIs), namely, Formoterol fumarate and Budesonide, and they were further investigated. All formulations exhibited spherical shape, appropriate aerodynamic performance, satisfying entrapment efficiency, and drug load. Their physicochemical properties were evaluated using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Differential Scanning Calorimetry (DSC). The aerodynamic particle size characterization was determined using an eight-stage Andersen cascade impactor, whereas the release of the actives was monitored in vitro in simulated lung fluid. Additional evaluation of the microparticles' mucoadhesive properties was performed by ζ-potential measurements and ex vivo mucoadhesion study applying a falling liquid film method using porcine lung tissue. Cytotoxicity and cellular uptake studies in Calu-3 lung epithelial cell line were conducted to further investigate the safety and efficacy of the developed formulations.

Solidification of volatile D-Limonene by cyclodextrin metal-organic framework for pulmonary delivery via dry powder inhalers: In vitro and in vivo evaluation

D-Limonene (D-Lim), a volatile oil extracted from citrus fruits, has therapeutic effects on lung inflammation and cancer, whilst the deep delivery of D-Lim was challenging due to its physical instability for a long period of time. To prevent the volatilization of D-Lim and achieve efficient pulmonary delivery, herein, D-Lim was loaded into biodegradable γ-cyclodextrin metal-organic framework (γ-CD-MOF) with optimal loading efficiency achieving 13.79 ± 0.01% (molar ratio of D-Lim and γ-CD-MOF was 1.6:1), which possessed cubic shape with controllable particle size (1-5 μm). The experimental results indicated that γ-CD-MOF could improve the stability of D-Lim. A series of characterizations and molecular docking were used to reveal the interaction between D-Lim and γ-CD-MOF. The solidification of D-Lim by γ-CD-MOF played a crucial role in the exploitation of its inhalable dosage form, dry powder inhaler (DPI). Specifically, the aerosolization of D-Lim@γ-CD-MOF for inhalation was satisfactory with a fine particle fraction (FPF) of 33.12 ± 1.50% at 65 L/min of flow rate. Furthermore, in vivo study had shown a 2.23-fold increase in bioavailability of D-Lim solidified by γ-CD-MOF for inhalation compared to D-Lim for oral administration. Therefore, it is considered that γ-CD-MOF could be an excellent carrier for pulmonary drug delivery to realize solidification and lung therapeutic effects of volatile oils.

A quantitative approach to predicting lung deposition profiles of pharmaceutical powder aerosols

Dry powder inhalers (DPI) are widely used systems for pulmonary delivery of therapeutics. The inhalation performance of DPIs is influenced by formulation features, inhaler device and inhalation pattern. The current review presents the affecting factors with great focus on powder characteristics which include particle size, shape, surface, density, hygroscopicity and crystallinity. The properties of a formulation are greatly influenced by a number of physicochemical factors of drug and added excipients. Since available particle engineering techniques result in particles with a set of modifications, it is difficult to distinguish the effect of an individual feature on powder deposition behavior. This necessitates developing a predictive model capable of describing all influential factors on dry powder inhaler delivery. Therefore, in the current study, a model was constructed to correlate the inhaler device properties, inhalation flow rate, particle characteristics and drug/excipient physicochemical properties with the resultant fine particle fraction. The r² value of established correlation was 0.74 indicating 86% variability in FPF values is explained by the model with the mean absolute errors of 0.22 for the predicted values. The authors believe that this model is capable of predicting the lung deposition pattern of a formulation with an acceptable precision when the type of inhaler device, inhalation flow rate, physicochemical behavior of active and inactive ingredients and the particle characteristics of DPI formulations are considered.

A study of hydrophobins-modified menaquinone-7 on osteoblastic cells differentiation

Menaquinone-7 is involved in bone metabolism and can be used to prevent and treat osteoporosis. However, as a fat-soluble vitamin, menaquinone-7 has poor water solubility. As a surfactant, hydrophobins can change the affinity/hydrophobicity of the covered interface. In this study, menaquinone-7 was modified by hydrophobins, and the different addition ratios were explored. Moreover, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements indicated that hydrophobins effectively bind to menaquinone-7 and greatly increase the hydrophilicity of the surface of menaquinone-7. Studies on the metabolism of MC3T3-E1 cells showed that compared with native menaquinone-7, HGFI-modified menaquinone-7 can significantly promote osteoblast differentiation but inhibit osteoclast differentiation. Besides, the Mito-Tracker Green experiments show that HGFI-modified menaquinone-7 can significantly promote the activity of mitochondria in cells. These findings indicate that hydrophobins can be used as an effective biomaterial to modify menaquinone-7, promote the formation of osteoblasts, and better to bone balance.

Enhancement of the apparent solubility and bioavailability of Tadalafil nanoparticles via antisolvent precipitation

The ability to increase the bioavailability and dissolution of poorly soluble hydrophobic drugs has been a major challenge for pharmaceutical development. This study shows that the dissolution rate, apparent solubility and oral bioavailability of tadalafil (Td) can be improved by nano-sized amorphous particles prepared by using antisolvent precipitation. Acetone and an acetone-water solution (v:v, 9:1) were selected as solvents, with deionized water as the antisolvent. The antisolvent precipitation process was conducted at a constant drug concentration of 10 mg/ml, at temperatures of 5, 10 and 15 °C and at volume ratios of antisolvent to solvent (AS/S) of 5, 8 and 10. Solid dispersion was achieved by dissolving the polymer in the antisolvent prior to the precipitation and by spray drying the suspension after the antisolvent precipitation process. The selected polymers were HPMC, VA64, and PVPK30 at concentrations of 33, 100 and 300 mg per 100 ml of water (equivalent to weight ratios of drug-to-polymer of 1:3, 1:1 and 3:1, respectively). The solid dispersions were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). The improvements in the dissolution rate, equilibrium solubility, apparent solubility and bioavailability were tested and compared with unprocessed Td. Td particles in the suspension (before spray drying) were 200 nm, and the obtained Td solid dispersion had a size of approximately 5-10 μm. The XRPD, DSC and FT-IR analyses confirmed that the prepared Td particles in the solid dispersions were amorphous. The solid dispersion obtained using the optimized process conditions exhibited 8.5 times faster dissolution rates in the first minute of dissolution, 22 times greater apparent solubility at 10 min and a 3.67-fold increase in oral bioavailability than the as-received Td. The present work demonstrated that low temperature antisolvent precipitation technique has excellent potential to prepare nano-sized amorphous particles with a faster release and a higher bioavailability.

High dose dry powder inhalers to overcome the challenges of tuberculosis treatment

Tuberculosis (TB) is a major global health burden. The emergence of the human immunodeficiency virus (HIV) epidemic and drug resistance has complicated global TB control. Pulmonary delivery of drugs using dry powder inhalers (DPI) is an emerging approach to treat TB. In comparison with the conventional pulmonary delivery for asthma and chronic obstructive pulmonary disease (COPD), TB requires high dose delivery to the lung. However, high dose delivery depends on the successful design of the inhaler device and the formulation of highly aerosolizable powders. Particle engineering techniques play an important role in the development of high dose dry powder formulations. This review focuses on the development of high dose dry powder formulations for TB treatment with background information on the challenges of the current treatment of TB and the potential for pulmonary delivery. Particle engineering techniques with a particular focus on the spray drying and a summary of the developed dry powder formulations using different techniques are also discussed.

Process, Physicochemical Characterization and In-Vitro Assessment of Albendazole Microcrystals

Purpose: Albendazole is a poorly soluble drug which limits its oral bioavailability. The study was focussed to enhance the solubility by in-situ micronization.

Methods: Albendazole microcrystals were prepared by solvent change method using gum karaya and hupu gum as stabilizing agents and the effect of each stabilizer on the prepared microcrystals were studied. FT-IR, DSC, XRD and SEM analysis were performed as a part of characterization studies. The formulations were evaluated for micromeritics, solubility and drug release. The microcrystals that had shown optimized properties were filled into suitable capsules.

Results: The formulations showed reduction in particle size with uniform size distribution and three folds increase in drug release. The microcrystals had shown more than 100-folds increase in solubility compared to pure drug. Surface energy, enthalpy and crystalline nature of microcrystals were found to be reduced. Microcrystals containing gum karaya had shown more drug release. The filled-in capsules also showed increase in drug release rate. The solubility enhancement of albendazole microcrystals was mainly due to the surface adsorption of the stabilizing agents that led to reduction in surface energy and crystalline nature as substantiated by the DSC and XRD studies. The type of stabilizing agent had significant effect on dissolution rate. High affinity of albendazole with gum karaya led to faster drug release profiles.

Conclusion: The study proved that in-situ micronization is an effective technique to enhance the solubility and dissolution rate of poorly soluble drugs like albendazole.

Evaluation of the Potential Use of Laminar Extrudates on Stabilizing Micronized Coumarin Particles by Supercritical Fluids (RESS)-Study of Different RESS Processing Variables and Mode of Operation

The study evaluates the ability of extrudates to deliver coumarin particles micronized by the rapid expansion of supercritical solutions (RESS). The RESS parameters were drug load (2-50 g), pressure (15-42 MPa) and temperature (40-60°C) in the extraction and pressure in the expansion (0.1-5 MPa) chambers in batch or continuous and CO₂ flow rate in the continuous mode of operation. Particles were characterized for size (laser diffractometry, optical and electronic microscopies-19-61 μm), surface area (BET-0.282-0.423 m²/g), density (pycnometry-1.273-1.358 g/cm³) and yield (2-70%). Extrudates were characterized for the force of extrusion (4 kN), release of coumarin (100%/24 h) and mechanical properties (bending strength and stiffness increased, whereas elasticity decreased in storage) and X-ray diffractometry (micronized particles and extrudates have shown identical patterns) and calorimetry (DSC, enthalpies increased on storage). In the discontinuous mode of operation, increased loads in the extraction or increased pressure in the expansion chambers led to larger particles, whereas increased temperature and pressure in the extraction chamber led to smaller particles. In the continuous mode of operation, a decrease on the expansion pressure, load and CO₂ flow rate led to increased yields. An increase on the flow rate led to a decrease on the particles' diameter, but an increase on coumarin load in the extraction chamber led to an increase in diameter. The study has identified the key parameters in RESS continuous and discontinuous modes of operation affecting the properties of the micronized coumarin particles and has proved the ability of extrudates with a laminar shape on delivering micronized particles.

Technological and practical challenges of dry powder inhalers and formulations

In the 50 years following the introduction of the first dry powder inhaler to the market, several developments have occurred. Multiple-unit dose and multi-dose devices have been introduced, but first generation capsule inhalers are still widely used for new formulations. Many new particle engineering techniques have been developed and considerable effort has been put in understanding the mechanisms that control particle interaction and powder dispersion during inhalation. Yet, several misconceptions about optimal inhaler performance manage to survive in modern literature. It is, for example still widely believed that a flow rate independent fine particle fraction contributes to an inhalation performance independent therapy, that dry powder inhalers perform best at 4 kPa (or 60 L/min) and that a high resistance device cannot be operated correctly by patients with reduced lung function. Nevertheless, there seems to be a great future for dry powder inhalation. Many new areas of interest for dry powder inhalation are explored and with the assistance of new techniques like computational fluid dynamics and emerging particle engineering technologies, this is likely to result in a new generation of inhaler devices and formulations, that will enable the introduction of new therapies based on inhaled medicines.

How can we bring high drug doses to the lung?

In the last decades, dry powder inhalation has become a very attractive option for pulmonary drug delivery to treat lung diseases like cystic fibroses and lung infections. In contrast to the traditional pulmonary application of drugs for asthma and chronic obstructive pulmonary disease, these therapies require higher lung doses to be administered. The developments and improvements toward high dose powder pulmonary drug delivery are summarized and discussed in this chapter. These include the invention and improvement of novel inhaler devices as well as the further development of formulation principles and new powder engineering methods. The implementation of these strategies is subsequently described for some prototypes and formulations in research and development stage as well as for already marketed dry powder products. Finally, possible adverse effects that can occur after inhalation of high powder doses are shortly addressed.

An overview on in situ micronization technique - An emerging novel concept in advanced drug delivery

The use of drug powders containing micronized drug particles has been increasing in several pharmaceutical dosage forms to overcome the dissolution and bioavailability problems. Most of the newly developed drugs are poorly water soluble which limits dissolution rate and bioavailability. The dissolution rate can be enhanced by micronization of the drug particles. The properties of the micronized drug substance such as particle size, size distribution, shape, surface properties, and agglomeration behaviour and powder flow are affected by the type of micronization technique used. Mechanical communition, spray drying and supercritical fluid (SCF) technology are the most commonly employed techniques for production of micronized drug particles but the characteristics of the resulting drug product cannot be controlled using these techniques. Hence, a newer technique called in situ micronization is developed in order to overcome the limitations associated with the other techniques. This review summarizes the existing knowledge on in situ micronization techniques. The properties of the resulting drug substance obtained by in situ micronization were also compared.

Preparation and in vitro aerosol performance of spray-dried Shuang-Huang-Lian corrugated particles in carrier-based dry powder inhalers

The development of dry powder inhalation (DPI) products of traditional Chinese medicine (TCM) remains to be a challenge due to chemical complexity and batch-to-batch variations in constituent composition. This study was to investigate the feasibility of using spray-dried corrugated particles to improve the aerodynamic performance of a TCM, Shuang-Huang-Lian (SHL), in carrier-based DPI. Particles with different surface roughness were spray-dried by the addition of leucine and concomitant manipulation of spray-drying parameters. The surface roughness was determined by atomic force microscopy, whilst the aerodynamic performance of drug particle-mannitol/lactose blends was evaluated using a next-generation pharmaceutical impactor through a Cyclohaler. Although the emission efficiency for corrugated particle-based DPI was ~10% lower than that for smooth SHL, the fine particle fractions (FPF(<4.4 μm)) of 32.4-36.8% for the former were significantly higher than those of 14.7-16.2% for the latter. In particular, the FPF and fraction of drug detached from the carrier appeared not to be significantly affected by the variation in constituent composition of SHL. This study demonstrates that the use of corrugated particles in carrier-based DPI improved aerosol performance by facilitating drug detachment from the carrier, independent of variation in constituent composition, and such particles were potentially applicable to the development of SHL DPI products.

Engineering drug ultrafine particles of beclomethasone dipropionate for dry powder inhalation

Beclomethasone dipropionate (BDP), which is a member in the inhaled glucocorticosteroid class, is commonly used in the treatment of asthma by pulmonary delivery. The purpose of this study is to prepare ultrafine BDP particles for dry powder inhalation (DPI) administration by combining microfluidic antisolvent precipitation without surfactant, high-pressure homogenization (HPH) and spray drying. T-junction microchannel was adopted for the preparation of needle-like BDP particles. The needle-like particles could be easily broken down into smaller particles during HPH, which were assembled into uniform low-density spherical BDP aggregates by spray drying. The effects of the operation parameters, such as the flow rates of BDP methanol solution and antisolvent, the overall flow rate, the BDP concentration, and the change of the injection phase on BDP particle size were explored. The results indicated that the BDP particle size greatly decreased with the reduction of BDP solution flow rate and the increase of antisolvent flow rate. However, the BDP particle size firstly decreased and then increased with the increase of the overall flow rate and the increase of BDP concentration. Also, BDP solution as the injection phase could form the smaller BDP particles. 10 HPH cycles are enough to forming short rod-like particles. After spray drying, the BDP spherical aggregates with a 2-3 μm size could be achieved. They have an excellent aerosol performance, 2.8 and 1.4 times as many as raw BDP and vacuum-dried BDP particles, respectively.

Pulmonary drug delivery strategies: A concise, systematic review

Because of limitations associated with the conventional treatment of various chronic diseases a growing attention has been given to the development of targeted drug delivery systems. Pulmonary route of drug delivery gaining much importance in the present day research field as it enables to target the drug delivery directly to lung both for local and systemic treatment. Over the last 2 decades, the systemic absorption of a broad range of therapeutics after pulmonary application has been demonstrated in animals as well as in humans. This review was prepared with an aim to discuss the technical, physiological, and efficacy aspects of the novel pulmonary route of drug targeting. The review also focuses on the mechanisms of pulmonary drug administration along with compatibility of the excipients employed, devices used, and techniques of particulate dosage production. This review was prepared based on the method of extensive literature survey on the topics covering all the aspects discussed in the present subject. Hence, the better understanding of complexes and challenges facing the development of pulmonary drug delivery system offer an opportunity to the pharmaceutical scientist in minimizing the clinical and technical gaps.

Edetate calcium disodium nanoparticle dry powder inhalation: a novel approach against heavy metal decorporation

Objective was to develop and characterize nano-edetate calcium disodium (Ca-Na(2)EDTA) dry powder inhaler (DPI), and assess its in vitro and in vivo deposition using pharmacoscintigraphy techniques. Factors influencing nanoparticle formation including concentration of drug, polymer solution and stirring rate were determined. Optimized formulation was characterized with the help of SEM, TEM and Malvern Zetasizer studies. Any change in physical characteristics after nanosizing was determined by FT-IR, XRD and DSC studies. Anderson cascade impaction showed that nano Ca-Na(2)EDTA exhibited significantly higher respirable fraction of 67.35±2.27% and 66.40±2.87% by scintigraphic and spectroscopic analysis respectively, as compared to 10.08±1.17% and 9.36±1.02% respectively for micronized form. Ventilation lung scintigraphy done in 12 volunteers showed significant increase in drug delivery till alveolar region with nano Ca-Na(2)EDTA. The developed formulation may have a role in neutralizing heavy metal toxicity through inhalation route, including radio-metal contamination.

Nanosized rods agglomerates as a new approach for formulation of a dry powder inhaler

Background:

Nanosized dry powder inhalers provide higher stability for poorly water-soluble drugs as compared with liquid formulations. However, the respirable particles must have a diameter of 1–5 μm in order to deposit in the lungs. Controlled agglomeration of the nanoparticles increases their geometric particle size so they can deposit easily in the lungs. In the lungs, they fall apart to reform nanoparticles, thus enhancing the dissolution rate of the drugs. Theophylline is a bronchodilator with poor solubility in water.

Methods:

Nanosized theophylline colloids were formed using an amphiphilic surfactant and destabilized using dilute sodium chloride solutions to form the agglomerates.

Results:

The theophylline nanoparticles thus obtained had an average particle size of 290 nm and a zeta potential of −39.5 mV, whereas the agglomerates were 2.47 μm in size with a zeta potential of −28.9 mV. The release profile was found to follow first-order kinetics (r² > 0.96). The aerodynamic characteristics of the agglomerated nanoparticles were determined using a cascade impactor. The behavior of the agglomerate was significantly better than unprocessed raw theophylline powder. In addition, the nanoparticles and agglomerates resulted in a significant improvement in the dissolution of theophylline.

Conclusion:

The results obtained lend support to the hypothesis that controlled agglomeration strategies provide an efficient approach for the delivery of poorly water-soluble drugs into the lungs.

Randomized phase II trial of inhaled budesonide versus placebo in high-risk individuals with CT screen-detected lung nodules

Screening CT identifies small peripheral lung nodules, some of which may be pre- or early invasive neoplasia. Secondary end point analysis of a previous chemoprevention trial in individuals with bronchial dysplasia showed reduction in size of peripheral nodules by inhaled budesonide. We performed a randomized, double-blind, placebo-controlled phase IIb trial of inhaled budesonide in current and former smokers with CT-detected lung nodules that were persistent for at least 1 year. A total of 202 individuals received inhaled budesonide, 800 μg twice daily or placebo for 1 year. The primary endpoint was the effect of treatment on target nodule size in a per person analysis after 1 year. The per person analysis showed no significant difference between the budesonide and placebo arms (response rate 2% and 1%, respectively). Although the per lesion analysis revealed a significant effect of budesonide on regression of existing target nodules (P = 0.02), the appearance of new lesions was similar in both groups and thus the significance was lost in the analysis of all lesions. The evaluation by nodule type revealed a nonsignificant trend toward regression of nonsolid and partially solid lesions after budesonide treatment. Budesonide was well tolerated, with no unexpected side effects identified. Treatment with inhaled budesonide for 1 year did not significantly affect peripheral lung nodule size. There was a trend toward regression of nonsolid and partially solid nodules after budesonide treatment. Because a subset of these nodules is more likely to represent precursors of adenocarcinoma, additional follow-up is needed.

Multifunctional hydrophobin: toward functional coatings for drug nanoparticles

Efficient delivery of nanosized drug formulations to the desired body sites is not always reached despite the rapid development of pharmaceutical nanotechnologies. In spite of the undoubted effect of the size for increased bioavailability and controlled drug delivery, submicrometer formulations also require a deeper level of design. The surface properties of the particles determine the stability of the particles, interactions with the body, and targeting potentials of drugs. Thus, the efficacy of the drug can be increased utilizing the surface layer of the nanoparticles. Influencing the surface characters of the drug is the main focus of the present work, which introduces a method for preparing nanoparticles with functional sites from low-solubility drugs using hydrophobin (HFB) proteins. Particles were prepared by precipitating a lipophilic drug (beclomethasone dipropionate) in water in the presence of the HFB proteins. Particle size below 200 nm could easily be reached with increasing HFB concentration. The particles were shown to be stable for at least 5 h in suspension, and they could be stored for longer periods of time after freeze-drying. Labeling studies using green fluorescent protein (GFP) genetically fused to a HFB clearly demonstrated that the surface of the nanoparticles was covered with the hydrophobins and that the surface could be further modified by utilizing fusion proteins. This provides a template for a variety of different functional surface-bound groups that could be tailored by modifying the hydrophilic side of the HFB via protein bioengineering. In this study, the combination of proteins and traditional pharmaceutical technology was used to synthesize functionalized protein-coated nanoparticles for drug delivery purposes.

Budesonide nanoparticle agglomerates as dry powder aerosols with rapid dissolution

Nanoparticle technology represents an attractive approach for formulating poorly water-soluble pulmonary medicines. Unfortunately, nanoparticle suspensions used in nebulizers or metered dose inhalers often suffer from physical instability in the form of uncontrolled agglomeration or Ostwald ripening. In addition, processing such suspensions into dry powders can yield broad particle size distributions. To address these encumbrances, a controlled nanoparticle flocculation process has been developed. Nanosuspensions of the poorly water-soluble drug budesonide were prepared by dissolving the drug in organic solvent containing surfactants followed by rapid solvent extraction in water. Different surfactants were employed to control the size and surface charge of the precipitated nanoparticles. Nanosuspensions were flocculated using leucine and lyophilized. Selected budesonide nanoparticle suspensions exhibited an average particle size ranging from approximately 160 to 230 nm, high yield and high drug content. Flocculated nanosuspensions produced micron-sized agglomerates. Freeze-drying the nanoparticle agglomerates yielded dry powders with desirable aerodynamic properties for inhalation therapy. In addition, the dissolution rates of dried nanoparticle agglomerate formulations were significantly faster than that of stock budesonide. The results of this study suggest that nanoparticle agglomerates possess the microstructure desired for lung deposition and the nanostructure to facilitate rapid dissolution of poorly water-soluble drugs.

Novel milk-based oral formulations: proof of concept

The aim of this study is to develop milk-based formulations for ionized and unionized lipophilic drugs. Solubility studies of the following non-steroidal anti-inflammatory drugs (NSAIDs): mefenamic acid, tolfenamic acid, ketoprofen, meloxicam, tenoxicam and nimesulide in phosphate- and glycine-NaOH buffers at nominal pH 8-12, were performed. The solubilities of cyclosporine and danazol in water-ethanol solutions were studied. NSAIDs-, cyclosporine-, danazol-, aspirin-milk oral liquid formulations were prepared by adding the appropriate volume of (i) NSAIDs-alkaline buffer solutions, (ii) water-ethanol solutions of cyclosporine and danazol and (iii) aspirin aqueous solution to 150-200ml of milk. All the non-steroidal anti-inflammatory drugs exhibited increased solubility in the alkaline buffers. The actual pH values (range 6.7-7.7) of the final NSAIDs-milk formulations were very close to milk pH. The higher ethanol content in ethanol-water mixtures increased the solubility of danazol and cyclosporine. A 15mg meloxicam-, a 100mg cyclosporine- and a 500mg aspirin-milk formulation was administered orally to healthy volunteers. All these formulations showed a satisfactory in vivo performance. The strong buffering capacity of milk that was observed and the high solubility of unionized drugs in ethanol allow the preparation of drug-milk formulations with enhanced pharmacokinetic properties.

Nanomedicine in pulmonary delivery

The lung is an attractive target for drug delivery due to noninvasive administration via inhalation aerosols, avoidance of first-pass metabolism, direct delivery to the site of action for the treatment of respiratory diseases, and the availability of a huge surface area for local drug action and systemic absorption of drug. Colloidal carriers (ie, nanocarrier systems) in pulmonary drug delivery offer many advantages such as the potential to achieve relatively uniform distribution of drug dose among the alveoli, achievement of improved solubility of the drug from its own aqueous solubility, a sustained drug release which consequently reduces dosing frequency, improves patient compliance, decreases incidence of side effects, and the potential of drug internalization by cells. This review focuses on the current status and explores the potential of colloidal carriers (ie, nanocarrier systems) in pulmonary drug delivery with special attention to their pharmaceutical aspects. Manufacturing processes, in vitro/in vivo evaluation methods, and regulatory/toxicity issues of nanomedicines in pulmonary delivery are also discussed.

Practical methods for improving flow properties of active pharmaceutical ingredients

OBJECTIVE

The essential aim of this article is to develop effective methods for improving the flow properties of active pharmaceutical ingredients (APIs) without requiring particle size or shape modification.

METHODS

The 'formulation' approach used here focuses on enhancing flow properties of three chemically different drug powders (micronized acetaminophen, levalbuterol tartrate, and didesmethylsibutramine tartrate) by using small amounts of lubricants, glidants, and other additives, both individually and in combination. Additives are intimately mixed using a laboratory-scale V-blender with an intensifier bar. Flow index, dilation, and electrical impedance were measured for a total of 24 blends.

RESULTS

The flow behavior of all three APIs improved with the addition of these additives. Relative effectiveness of different additive combinations displayed remarkable consistency for all three APIs. Simultaneous presence of SiO2, MgSt, and talc led to substantial decreases in cohesiveness, causing major improvements in flowability of powder. All three properties showed a very tight correlation.

CONCLUSIONS

Drug powders with improved flow were found to exhibit low dilation and low impedance values. A common linear correlation between flow index and impedance and also between dilation and impedance was observed for all three APIs, indicating that electric properties play a substantial role in the cohesivity of all three APIs, and suggesting the presence of a common mechanism for the emergence (and mitigation) of cohesive phenomena.