Characterisation and deposition studies of recrystallised lactose from binary mixtures of ethanol/butanol for improved drug delivery from dry powder inhalers

Improving Inhalation Performance with Particle Agglomeration via Combining Mechanical Dry Coating and Ultrasonic Vibration

Agglomerate formulations for dry powder inhalation (DPI) formed with fine particles are versatile means for the highly efficient delivery of budesonide. However, uncontrolled agglomeration induces high deposition in the upper airway, causing local side effects due to high mechanical strength, worse deagglomeration, and poor fine-particle delivery. In the present study, fine lactose was mechanically dry-coated prior to particle agglomeration, and the agglomerates were then spheroidized via ultrasonic vibration to improve their aerosol performance. The results showed that the agglomerate produced with the surface-enriched hydrophobic magnesium stearate and ultrasonic vibration demonstrated improved aerosolization properties, benefiting from their lower mechanical strength, less interactive cohesive force, and improved fine powder dispersion behavior. After dispersion utilizing a Turbuhaler® with a pharmaceutical cascade impactor test, a fine particle fraction (FPF) of 71.1 ± 1.3% and an artificial throat deposition of 19.3 ± 0.4% were achieved, suggesting the potential to improve the therapeutic outcomes of budesonide with less localized infections of the mouth and pharynx.

Thermal characteristics of crystalline and amorphous 2'-fucosyllactose, a human milk oligosaccharide

The thermal characteristics of crystalline and amorphous forms of a human milk oligosaccharide, 2'-fucosyllactose (2'-FL), were investigated by differential scanning calorimetry and thermogravimetric analysis, and compared with the two forms of α-lactose monohydrate. Crystalline 2'-FL (87.48% crystallinity according to X-ray diffraction) showed dehydration at 143.4 °C (close to lactose) and melting at 230.6 °C (the same as β-lactose crystal). Amorphous 2'-FL showed glass transition at 127.6 °C and crystallisation at 192.8 °C, which were much higher than the corresponding temperatures for amorphous lactose. 2'-FL showed thermal decomposition at temperatures about 10 °C higher (210-212 °C) than lactose, indicating the higher thermal stability of 2'-FL. Amorphous 2'-FL showed sharp decreases in glass transition (127.6 °C to 36.5 °C) and crystallisation (192.8 °C to 103.4 °C) temperatures with increasing water activity (a_w) from 0 to 0.53, above which no glass transition or crystallisation was observed.

Bimodal Release Two-In-One Clonazepam Matrix Lozenge Tablets for Managing Anxiety-Related Disorders: Formulation, Optimization and In Vivo Evaluation

Clonazepam (CLZ), an antipsychotic drug reported for its efficiency in managing anxiety-related disorders, is being marketed only as conventional tablets. Some patients have abstention to swallow the conventional tablets; therefore, the proposed study was aimed at developing a buccal lozenge tablet by direct compression of two types of optimized granules. Conazepam’s water solubility was first enhanced by a solid dispersion technique for a fast and better dissolution of type 1 granules, while the impact of gelling polymers was investigated on controlled-release type 2 granules. The optimized formulae met the acceptable pharmacopeial limits for tablets’ evaluation. A differential scanning calorimetry study revealed the compatibility between the drug and used excipients. All formulae gave a burst release of CLZ in the first hour of investigation, followed by a sustained release over 24 h. The formula that showed the highest prolonged in vitro release (99.0 + 0.1%), following the Higuchi diffusion model (R2 = 0.99), was then selected for further study. The formula succeeded in controlling the induced stress in a rat model with a significant impact on the behavioral tests throughout the experiment. The results were further confirmed by a pharmacokinetic study that showed a significant increase in Cmax, Tmax, and AUC (1.5, 2, and 3.9 folds), respectively, compared to oral suspension. The newly proposed delivery system has proven a better efficacy with a reduced dosing frequency.

Optimising the release rate of naproxen liqui-pellet: a new technology for emerging novel oral dosage form

Liqui-pellet is a new dosage form stemming from pelletisation technology and concept from liquisolid technology. In spite of liqui-pellet overcoming a major hurdle in liquisolid technology through achieving excellent flow property with high liquid load factor, the formulation requires to be optimised in order to improve drug release rate. Liqui-pellets of naproxen containing Tween 80, Primojel, Avicel and Aerosil were extruded and spheronised. Flowability test confirmed that all liqui-pellet formulations have excellent-good flow property (Carr's index between 3.9-11.17%), including liqui-pellets with a high liquid load factor of 1.52, where 38% of the total mass is co-solvent. This shows a relatively high liquid load factor can be achieved in liqui-pellet without compromising the flowability, which is one of the key novelty of this work. It was found that the improved drug release rate was due to the remarkably improved disintegration of the supposedly non-disintegrating microcrystalline-based pellet; the optimised liqui-pellet seems to explode into fragments in the dissolution medium. At pH 1.2, the optimised formulation had ~ 10% more drug release than non-optimised formulation after 2 h, and at pH 7.4, the drug release of the optimised pellet was nearing 100% at ~ 15 min, whereas the none-optimised pellet only achieved ~ 79% drug release after 2 h. DSC and XRPD indicated an increase in the dissolution rate could be due to molecularly dispersion of naproxen in the pellets. Overall results showed that liqui-pellet exhibited an enhanced drug release and the capacity for high liquid load factor whilst maintaining excellent flowability, rendering it a potentially commercially feasible drug delivery system.

Co-electrospraying technology as a novel approach for dry powder inhalation formulation of montelukast and budesonide for pulmonary co-delivery

In the current study electrospraying methodology was used for particle engineering of montelukast and budesonide to prepare a combined inhalable dry powder formulation applicable as a smart regimen in asthma treatment. For this, electrospraying was carried out using different solvents and drug concentrations. No carrier was added for the formulation of montelukast-budesonide combination as montelukast played the role of both active ingredient and carrier. Scanning electron microscopy, particle size analysis, gas chromatography, powder X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry were used to evaluate the physicochemical properties of the produced drug particles. In vitro drug deposition pattern was assessed using next generation impactor, and the dissolution profile of the selected formulations was characterized via modified diffusion franz cell method. The FPF value for the co-electrosprayed carrier free formulation of montelukast-budesonide was 38% with a significantly enhanced dissolution rate for budesonide compared to the budesonide alone formulations. The pharmacological effects of hypothesized combined formulation was assessed by measuring its power to inhibit the production of reactive oxygen species in human normal lung cells. The results showed that the combination of montelukast and budesonide can exert a synergistic effect. The findings in the current study emphasize that using montelukast as a carrier for budesonide not only has greatly improved the aerosolization behavior and dissolution rate of budesonide but also has resulted in synergistic pharmacological effects, indicating the suitability of this combination as an anti-asthmatic therapeutic.

Development of an Innovative, Carrier-Based Dry Powder Inhalation Formulation Containing Spray-Dried Meloxicam Potassium to Improve the In Vitro and In Silico Aerodynamic Properties

Most of the marketed dry powder inhalation (DPI) products are traditional, carrier-based formulations with low drug concentrations deposited in the lung. However, due to their advantageous properties, their development has become justified. In our present work, we developed an innovative, carrier-based DPI system, which is an interactive physical blend of a surface-modified carrier and a spray-dried drug with suitable shape and size for pulmonary application. Meloxicam potassium, a nonsteroidal anti-inflammatory drug (NSAID), was used as an active ingredient due to its local anti-inflammatory effect and ability to decrease the progression of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The results of the in vitro and in silico investigations showed high lung deposition in the case of this new formulation, confirming that the interparticle interactions were changed favorably.

Co-spraying of carriers (mannitol-lactose) as a method to improve aerosolization performance of salbutamol sulfate dry powder inhaler

Although in dry powder inhaler (DPI) formulations a single carrier is used, a single carrier is not able to provide an excellent aerosolization performance when it is used in DPI formulations. Thereby, the aim of this study was to engineer a suitable ternary mixture of mannitol-lactose-leucine to be used in a DPI formulation with enhanced aerosolization performance. To this end, binary mixtures of mannitol:lactose containing a constant amount of leucine (5% w/w of carriers) were spray-dried as a single solution. Spray-dried samples were blended with salbutamol sulfate to determine the efficiency of their aerosolization performance. Interestingly, note that lactose was in its amorphous state stabilized by the presence of mannitol in the samples. Spray-dried mannitol without lactose showed a combination of the α- and β-polymorphic forms which was the case in all other ratios of mannitol:lactose. It was shown that the highest fine particle fraction (FPF) was 62.42 ± 4.21% which was obtained for the distinct binary mixtures (1:3 mannitol:lactose) compared to a single carrier. This study opens a new window to investigate further the implementation of binary mixtures of sugar carriers containing leucine in DPI formulations to overcome poor aerosolization performance the mentioned DPI formulations.

An exploration of the solvent- and acid-catalyzed mutarotation mechanisms of lactose in aqueous solution

Exploration of the solvent- and acid-catalyzed mutarotation mechanisms of lactose to reveal the ease of the mutarotation varying with the acidity of the catalyst.

Effect of Roughness on the Dispersion of Dry Powders for Inhalation: a Dynamic Visualization Perspective

Dry powder inhalers have attracted more interest over the years in every aspect related to them. Interestingly, when focusing on the effects of particle morphology of the active or carrier (excipient), it is generally regarded particle size and shape to influence drug availability of aerosolized particles. However, to date, few studies have examined the effect of texture, i.e., roughness, on this relationship. The main objective of the present work is to gain a closer understanding of the influence of carrier morphology on the aerosolization performance of dry powder inhaler formulations. Image analysis and microscopy were used to visualize the aerosolization process. It is considered that the scale of morphological features on the surface of the carrier particles is responsible for the dispersion of the powder formulation, separation of the drug/carrier, and entrainment from a dry powder inhaler. Thus, for this study, the carrier particles of different surface roughness were mixed with micronized salbutamol sulphate. Aerosolization in vitro testing was used to evaluate the performance. The results indicate a connection between the qualitative surface roughness of coarse carriers and aerosolization performance during powder dispersibility. This investigation demonstrated that indeed, powder dispersion, a dynamic process, is influenced by the scale of the carrier morphology.

Liqui-Pellet: the Emerging Next-Generation Oral Dosage Form Which Stems from Liquisolid Concept in Combination with Pelletization Technology

In spite of the major advantages that the liquisolid technology offers, particularly in tackling poor bioavailability of poorly water-soluble drugs (i.e., BCS Class II drugs), there are a few critical drawbacks. The inability of a high liquid load factor, poor flowability, poor compactibility, and an inability to produce a high dose dosage form of a reasonable size for swallowing are major hurdles, hampering this technology from being commercially feasible. An attempt was therefore made to overcome these drawbacks whilst maintaining the liquisolid inherent advantages. This resulted in the emerging next generation of oral dosage forms called the liqui-pellet. All formulations were incorporated into capsules as the final product. Solubility studies of naproxen were conducted in different liquid vehicles, namely polyethylene glycol 200, propylene glycol, Tween 80, Labrafil, Labrasol, and Kolliphor EL. The scanning electron microscopy studies indicated that the liquid vehicle tends to reduce the surface roughness of the pellet. X-ray powder diffraction (XRPD) indicated no significant differences in the crystalline structure or amorphous content between the physical mixture and the liqui-pellet formulation. This was due to the presence of a high concentration of amorphous Avicel in the formulation which overshadowed the crystalline structure of naproxen in the physical mixtures. Flowability and dissolution tests confirmed that this next-generation oral dosage form has excellent flowability, whilst maintaining the typical liquisolid enhanced drug release performance in comparison to its physical mixture counterpart. The liqui-pellet also had a high liquid load factor of 1, where ~ 29% of the total mass was the liquid vehicle. This shows that a high liquid load factor can be achieved in a liqui-pellet without compromising flowability. Overall, the results showed that the poor flowability of a liquisolid formulation could be overcomed with the liqui-pellet, which is believed to be a major advancement into the commercial feasibility of the liquisolid concept.

Agglomerated novel spray-dried lactose-leucine tailored as a carrier to enhance the aerosolization performance of salbutamol sulfate from DPI formulations

Spray-drying allows to modify the physicochemical/mechanical properties of particles along with their morphology. In the present study, _L-leucine with varying concentrations (0.1, 0.5, 1, 5, and 10% w/v) were incorporated into lactose monohydrate solution for spray-drying to enhance the aerosolization performance of dry powder inhalers containing spray-dried lactose-leucine and salbutamol sulfate. The prepared spray-dried lactose-leucine carriers were analyzed using laser diffraction (particle size), differential scanning calorimetry (thermal behavior), scanning electron microscopy (morphology), powder X-ray diffraction (crystallinity), Fourier transform infrared spectroscopy (interaction at molecular level), and in vitro aerosolization performance (deposition). The results showed that the efficacy of salbutamol sulfate’s aerosolization performance was, in part, due to the introduction of _L-leucine in the carrier, prior to being spray-dried, accounting for an increase in the fine particle fraction (FPF) of salbutamol sulfate from spray-dried lactose-leucine (0.5% leucine) in comparison to all other carriers. It was shown that all of the spray-dried carriers were spherical in their morphology with some agglomerates and contained a mixture of amorphous, α-lactose, and β-lactose. It was also interesting to note that spray-dried lactose-leucine particles were agglomerated during the spray-drying process to make coarse particles (volume mean diameter of 79 to 87 μm) suitable as a carrier in DPI formulations.

A review on recent technologies for the manufacture of pulmonary drugs

This review discusses recent developments in the manufacture of inhalable dry powder formulations. Pulmonary drugs have distinct advantages compared with other drug administration routes. However, requirements of drugs properties complicate the manufacture. Control over crystallization to make particles with the desired properties in a single step is often infeasible, which calls for micronization techniques. Although spray drying produces particles in the desired size range, a stable solid state may not be attainable. Supercritical fluids may be used as a solvent or antisolvent, which significantly reduces solvent waste. Future directions include application areas such as biopharmaceuticals for dry powder inhalers and new processing strategies to improve the control over particle formation such as continuous manufacturing with in-line process analytical technologies.

Imagine the Superiority of Dry Powder Inhalers from Carrier Engineering

Inhalation therapy has strong history of more than 4000 years and it is well recognized around the globe within every culture. In early days, inhalation therapy was designed for treatment of local disorders such as asthma and other pulmonary diseases. Almost all inhalation products composed a simple formulation of a carrier, usually α-lactose monohydrate orderly mixed with micronized therapeutic agent. Most of these formulations lacked satisfactory pulmonary deposition and dispersion. Thus, various alternative carrier's molecules and powder processing techniques are increasingly investigated to achieve suitable aerodynamic performance. In view of this fact, more suitable and economic alternative carrier's molecules with advanced formulation strategies are discussed in the present review. Furthermore, major advances, challenges, and the future perspective are discussed.

Microencapsulated Solid Lipid Nanoparticles as a Hybrid Platform for Pulmonary Antibiotic Delivery

Solid lipid nanoparticles (SLN) containing rifabutin (RFB), with pulmonary administration purposes, were developed through a technique that avoids the use of organic solvents or sonication. To facilitate their pulmonary delivery, the RFB-loaded SLN were included in microspheres of appropriate size using suitable excipients (mannitol and trehalose) through a spray-drying technique. Confocal analysis microscopy showed that microspheres are spherical and that SLN are efficiently microencapsulated and homogeneously distributed throughout the microsphere matrices. The aerodynamic diameters observed an optimal distribution for reaching the alveolar region. The dry powder's performance during aerosolization and the in vitro drug deposition were tested using a twin-impinger approach, which confirmed that the microspheres can reach the deep lung. Isothermal titration calorimetry revealed that SLN have higher affinity for mannitol than for trehalose. Upon microsphere dissolution in aqueous media, SLN were readily recovered, maintaining their physicochemical properties. When these dry powders reach the deep lung, microspheres are expected to readily dissolve, delivering the SLN which, in turn, will release RFB. The in vivo biodistribution of microencapsulated RFB-SLN demonstrated that the antibiotic achieved the tested organs 15 and 30 min post pulmonary administration. Their antimycobacterial activity was also evaluated in a murine model of infection with a Mycobacterium tuberculosis strain H37Rv resulting in an enhancement of activity against M. tuberculosis infection compared to nontreated animals. These results suggest that RFB-SLN microencapsulation is a promising approach for the treatment of tuberculosis.

On the effects of blending, physicochemical properties, and their interactions on the performance of carrier-based dry powders for inhalation - A review

Blending drug and carrier powders to produce homogeneous drug-carrier adhesive mixtures is a key step in the production of dry powder inhaler (DPI) formulations. Although the blending conditions can result in different conclusions or probably change the outcome of a study entirely if being selected differently, there is a scarcity of data on the influence of blending processes on the physicochemical properties of bulk powder formulations and the follow-on effects on DPI performance. This paper provides an overview of the interactions between variables related to blending conditions (e.g. blending equipment, time, speed and sequence as well as environmental humidity) and powder physicochemical properties (e.g. size distribution, shape distribution, density, anomeric composition, electrostatic charge, surface, and bulk properties), and their effects on the performance of adhesive mixtures for inhalation in terms of drug content homogeneity, drug-carrier adhesion, and drug aerosolisation behaviour. The relevance of carrier payload, batch size and segregation was also discussed. Challenges and future directions were identified. This review therefore contributes towards a better understanding of the blending process, powder physicochemical properties, and their interlinked effects on the fundamental understanding of adhesive mixtures for inhalation. The knowledge gained is essential to ensure optimum blending and thereby controlled functionality of DPIs.

An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.

An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.

Liquid crystalline phase as a probe for crystal engineering of lactose: carrier for pulmonary drug delivery

The current work was undertaken to assess suitability of liquid crystalline phase for engineering of lactose crystals and their utility as a carrier in dry powder inhalation formulations. Saturated lactose solution was poured in molten glyceryl monooleate which subsequently transformed into gel. The gel microstructure was analyzed by PPL microscopy and SAXS. Lactose particles recovered from gels after 48 h were analyzed for polymorphism using techniques such as FTIR, XRD, DSC and TGA. Particle size, morphology and aerosolisation properties of prepared lactose were analyzed using Anderson cascade impactor. In situ seeding followed by growth of lactose crystals took place in gels with cubic microstructure as revealed by PPL microscopy and SAXS. Elongated (size ∼ 71 μm) lactose particles with smooth surface containing mixture of α and β-lactose was recovered from gel, however percentage of α-lactose was more as compared to β-lactose. The aerosolisation parameters such as RD, ED, %FPF and % recovery of lactose recovered from gel (LPL) were found to be comparable to Respitose® ML001. Thus LC phase (cubic) can be used for engineering of lactose crystals so as to obtain particles with smooth surface, high elongation ratio and further they can be used as carrier in DPI formulations.

Comparative evaluation of drug release from aged prolonged polyethylene oxide tablet matrices: effect of excipient and drug type

Polyethylene oxide (PEO) undergoes structural adjustments caused by elevated temperatures, which results in loss of its stability within direct compression tablets. The aim of this study was to evaluate the influence of filler solubility on the drug delivery process of matrix tablets containing drugs with different water-solubility properties and stored at elevated temperature. The results demonstrated that in the case of propranolol HCl (highly water-soluble) tablet matrices, soluble lactose promoted drug release, whereas, a stable release of drug was observed with insoluble DCP. A drug release pattern similar to the propranolol HCl formulation containing DCP was obtained for hydrophilic matrix tablets containing either lactose or DCP for the less water-soluble drug, zonisamide. In the case of the partially water-soluble drug, theophylline, formulated with lower molecular weight PEO 750, drug release increased considerably in the presence of both fillers with increasing storage time, however a stable release rate (similar to fresh samples) was observed in the case of higher molecular weight PEO 303 tablet matrices containing theophylline with either lactose or DCP. The hydration properties (e.g. solubility) of the diluents had a considerable effect on drug release behavior from various model matrices; this effect was dependent on both molecular weight of PEO and solubility of drug.

Alternative carriers in dry powder inhaler formulations

The aerosolization efficiency of a powder is highly dependent on carrier characteristics, such as particle size distribution, shape and surface properties. The main objective in the inhalation field is to achieve a high and reproducible pulmonary deposition. This can be provided by successful carrier selection and careful process optimization for carrier modification. Lactose is the most common and frequently used carrier in dry powder inhaler (DPI) formulations. But lactose shows some limitations in formulation with certain drugs and peptides that prohibit its usage as a carrier in DPI formulations. Here, we criticality review the most important alternative carriers to lactose with merits, demerits and applications in DPI formulations.

Towards a more desirable dry powder inhaler formulation: large spray-dried mannitol microspheres outperform small microspheres

PURPOSE

To investigate, for the first time, the performance of a dry powder inhaler (DPI, Aerolizer(®)) in the case of a model drug (i.e. albuterol sulphate) formulated with spray dried mannitol carrier particles with homogeneous shape and solid-state form but different sizes.

METHODS

Spray dried mannitol (SDM) particles were characterized in terms of size, surface area, morphology, water content, solid-state, density and electrostatic charge by a novel approach. DPI formulations composed of SDM and albuterol sulphate (AS) were prepared and evaluated in terms of drug content homogeneity and in vitro aerosolization performance.

RESULTS

All SDM particles generated similar fine particle fractions of AS. Formulations consisting of larger SDM particles demonstrated better drug content homogeneity, reduced amounts of drug loss and reduced oropharyngeal deposition. Comparing different SDM products demonstrated that SDM powders with relatively poorer flowability, wider size distributions and higher charge density generated DPI formulations with poorer drug content homogeneity and deposited higher amount of drug on the inhaler, mouthpiece adaptor and throat. DPI formulation total desirability increased linearly with the mean diameter of SDM.

CONCLUSION

Particle shape and solid-state form of mannitol could dominate over carrier size, bulk density, flowability and charge in terms of determining the aerosolization behaviour of AS formulated with mannitol carrier, at least within the experimental protocols applied in the present study.

Engineered mannitol ternary additives improve dispersion of lactose-salbutamol sulphate dry powder inhalations

The aim of this study was to evaluate the influence of novel engineered fine mannitol particles (4.7%, w/w) on the performance of lactose-salbutamol sulphate dry powder inhaler (DPI) formulations to obtain promising aerosolisation properties. The results showed that the more elongated the fine mannitol particles, the weaker the drug-carrier adhesion, the better the drug content homogeneity, the higher the amount of drug expected to be delivered to the lower airways and the higher the total DPI formulation desirability. Linear relationships were established showing that mannitol particles with a more elongated shape generated powders with broader size distributions and that were less uniform in shape. The weaker the drug-carrier adhesion, the higher the fine particle fraction of the drug is upon aerosolisation. It is believed that more elongated fine mannitol particles reduce the number of drug-carrier and drug-drug physical contact points and increase the ability of the drug particles to travel into the lower airways. Additionally, a lower drug-carrier contact area, lower drug-carrier press-on forces and easier drug-carrier detachment are suggested in the case of formulations containing more elongated fine mannitol particles. Ternary 'drug-coarse carrier-elongated fine ternary component' DPI formulations were more favourable than both 'drug-coarse carrier' and 'drug-elongated coarse carrier' binary formulations. This study provides a comprehensive approach for formulators to overcome the undesirable properties of dry powder inhalers, as both improved aerosolisation performance and reasonable flow characteristics were obtained using only a small amount of elongated engineered fine mannitol particles.

Treating mannitol in a saturated solution of mannitol: a novel approach to modify mannitol crystals for improved drug delivery to the lungs

The aim of this study was to evaluate the influence of treatment of a promising dry powder aerosol carrier (mannitol) on the aerosolization performance of salbutamol sulphate (SS) using a novel approach: treating excess commercial carrier particles in a saturated solution of the same carrier. Commercial mannitol (CM) particles were treated with aqueous mannitol supersaturated solutions (20% and 25% w/v), under stirring, (300 rpm) for either 24h or 48 h. The results showed that particle treatment did not alter the polymorphic form of mannitol (β-mannitol); however, all treated mannitol particles demonstrated smoother surface topography and improved aerosolization performance compared to CM in dry powder inhalations. Unlike the concentration of mannitol solution used during treatment, the time of treatment to collect mannitol crystals was an essential key to modify the physical properties of mannitol and its effect on the aerosolization performance. In comparison to mannitol particles treated for 48 h, mannitol particles treated for 24h demonstrated larger size, more elongated-less regular shape, and smoother surfaces. No apparent relationship was obtained between in vitro aerosolisation behavior of SS with either mannitol particle size or shape descriptors. However, despite their larger size and more irregular-less uniformed shape, treated mannitol particles with smoother surfaces generated drug particles with smaller aerodynamic size and are expected to deliver higher amounts of drug to lower airways. The results demonstrated the potential of treating mannitol particles in aqueous solutions of the same material under controlled conditions to produce mannitol particles promising for dry powder inhaler systems. The results suggested that mannitol particle surface texture properties dominate over both particle size and particle shape of mannitol in terms of determining the aerosolization performance of mannitol.

Freeze-dried mannitol for superior pulmonary drug delivery via dry powder inhaler

PURPOSE

To show for the first time the superior dry powder inhaler (DPI) performance of freeze dried mannitol in comparison to spray dried mannitol and commercial mannitol.

METHODS

Different mannitol powders were sieved to collect 63-90 μm particles and then analyzed in terms of size, shape, surface morphology, solid state, density, flowability. Salbutamol sulphate-mannitol aerosol formulations were evaluated in terms of homogeneity, SS-mannitol adhesion, and in vitro aerosolization performance.

RESULTS

Freeze dried mannitol demonstrated superior DPI performance with a fine particle fraction believed to be highest so far reported in literature for salbutamol sulphate under similar protocols (FPF = 46.9%). To lesser extent, spray dried mannitol produced better aerosolization performance than commercial mannitol. Freeze dried mannitol demonstrated elongated morphology, α-+β-+δ- polymorphic forms, and poor flowability whereas spray dried mannitol demonstrated spherical morphology, α-+β- polymorphic forms, and excellent flowability. Commercial mannitol demonstrated angular morphology, β- polymorphic form, and good flowability. Freeze dried mannitol demonstrated smoother surface than spray dried mannitol which in turn demonstrated smoother surface than commercial mannitol. FPF of SS increased as mannitol powder porosity increase.

CONCLUSIONS

Freeze drying under controlled conditions can be used as a potential technique to generate aerodynamically light mannitol particles for superior DPI performance.

Antisolvent crystallisation is a potential technique to prepare engineered lactose with promising aerosolisation properties: effect of saturation degree

Engineered lactose particles were prepared by anti-solvent crystallisation technique using lactose solutions with different saturation degrees. In comparison to commercial lactose, engineered lactose particles exhibited less elongated and more irregular shape (large aggregates composed of smaller sub-units), rougher surface texture, higher specific surface area, and different anomer form. Engineered lactose powders demonstrated smaller bulk density, smaller tap density, and higher porosity than commercial lactose powder. Dry powder inhaler (DPI) formulations containing engineered lactose and salbutamol sulphate as a model drug demonstrated improved drug content homogeneity and higher amounts of drug delivered to lower airway regions. Higher fine particle fraction of drug was obtained in the case of lactose powders with higher porosity, higher specific surface area and higher fine particle content (<5 μm). The results indicated that the higher the saturation degree of lactose solution used during crystallisation the smaller the specific surface area, the higher the amorphous lactose content, and the higher the β-lactose content of engineered lactose particles. Also, lactose powders obtained from lactose solution with higher degree of saturation showed higher bulk and tap densities and smaller porosity. Engineered lactose powders crystallized from lower saturation degree (20% and 30% w/v) deposited higher amounts of drug on lower airway regions. In conclusion, this study demonstrated that it is possible to prepare engineered lactose particles with favourable properties (e.g. higher fine particle fraction and better drug content homogeneity) for DPI formulations by using lactose solutions with lower degree of saturation during crystallisation process.

The effect of engineered mannitol-lactose mixture on dry powder inhaler performance

PURPOSE

To co-crystallise mannitol and lactose with a view to obtaining crystals with more favourable morphological features than either lactose or mannitol alone, suitable for use as carriers in formulations for dry powder inhalers (DPIs) using simultaneous engineering of lactose-mannitol mixtures.

METHODS

Mannitol and lactose individually and the two sugars with three different ratios were crystallised/co-crystallised using anti-solvent precipitation technique. Obtained crystals were sieved to separate 63-90 μm size fractions and then characterised by size, shape, density and in vitro aerosolisation performance. Solid state of crystallized samples was studied using FT-IR, XRPD and DSC.

RESULTS

At unequal ratios of mannitol to lactose, the elongated shape dominated in the crystallisation process. However, lactose exerted an opposite effect to that of mannitol by reducing elongation ratio and increasing the crystals' width and thickness. Crystallised β-lactose showed different anomers compared to commercial lactose (α-lactose monohydrate). Crystallised α-mannitol showed different polymorphic form compared to commercial mannitol (β-mannitol). Crystallised mannitol:lactose showed up to 5 transitions corresponding to α-mannitol, α-lactose monohydrate, β-lactose, 5α-/3β-lactose and 4α-/1β-lactose. In vitro deposition assessments showed that crystallised carriers produced more efficient delivery of salbutamol sulphate compared to formulations containing commercial grade carriers.

CONCLUSION

The simultaneous crystallization of lactose-mannitol can be used as a new approach to improve the performance of DPI formulations.

Advanced microscopy techniques to assess solid-state properties of inhalation medicines

Efficient control and characterisation of the physico-chemical properties of active pharmaceutical ingredients (APIs) and excipients for orally inhaled drug products (OIDPs) are critical to successful product development. Control and reduction of risk require the introduction of a material science based approach to product development and the use of advanced analytical tools in understanding how the solid-state properties of the input materials influence structure and product functionality. The key issues to be addressed, at a microscopic scale, are understanding how the critical quality attributes of input materials influence surface, interfacial and particulate interactions within OIDPs. This review offers an in-depth discussion on the use of advanced microscopy techniques in characterising of the solid-state properties of particulate materials for OIDPs. The review covers the fundamental principles of the techniques, instrumentation types, data interpretation and specific applications in relation to the product development of OIDPs.

Effect of carrier particle shape on dry powder inhaler performance

The aim of this study was to characterise the aerosolisation properties of salbutamol sulphate (SS) from dry powder inhaler (DPI) formulations containing different carrier products. The difference in the elongation ratio (ER) of the different carriers was highlighted. Different set of carriers, namely commercial mannitol (CM), commercial lactose (CL), cooling crystallised mannitol (CCM), acetone crystallised mannitol (ACM) and ethanol crystallised mannitol (ECM) were used and inspected in terms of size, shape, density, crystal form, flowability, and in vitro aerosolisation performance using Multi Stage Liquid Impinger (MSLI) and Aerolizer inhaler device. Solid-state and morphological characterization showed that CM product was in pure β-form having particles with smaller ER (CM: ER=1.62 ± 0.04) whereas ACM and ECM mannitol particles were in pure α form with higher ER (ACM: ER=4.83 ± 0.18, ECM: ER=5.89 ± 0.19). CCM product crystallised as mixtures of β-form and δ-form and showed the largest variability in terms of particle shape, size, and DPI performance. Linear relationships were established showing that carrier products with higher ER have smaller bulk density (D(b)), smaller tap density (D(t)), higher porosity (P), and poorer flow properties. In vitro aerosolisation assessments showed that the higher the ER of the carrier particles the greater the amounts of SS delivered to lower airway regions indicating enhanced DPI performance. Yet, DPI performance enhancement by increasing carrier ER reached a "limit" as increasing carrier ER from 4.83±0.18 (ACM) to 5.89±0.19 (ECM) did not significantly alter fine particle fraction (FPF) of SS. Also, carrier particles with higher ER were disadvantageous in terms of higher amounts of SS remained in inhaler device (drug loss) and deposited on throat. Linear relationship was established (r(2)=0.87) showing that the higher the carrier ER the lower the drug emission (EM) upon inhalation. Moreover, poorer flowability for carrier products with higher ER is disadvantageous in terms of DPI formulation dose metering and processing on handling scale. In conclusion, despite that using carrier particles with higher ER can considerably increase the amounts of drug delivered to lower airway regions; this enhancement is restricted to certain point. Also, other limitations should be taken into account including higher drug loss and poorer flowability.

The influence of physical properties and morphology of crystallised lactose on delivery of salbutamol sulphate from dry powder inhalers

The aim of this work was to investigate the mechanistic evaluation of physicochemical properties of new engineered lactose on aerosolisation performance of salbutamol sulphate (SS) delivered from dry powder inhaler (DPI). Different crystallised lactose particles were obtained from binary mixtures of butanol:acetone. The sieved fractions (63-90 μm) of crystallised lactose were characterised in terms of size, shape, flowability, true density and aerosolisation performance (using multiple twin stage impinger (MSLI), Aerolizer(®) inhaler device, and salbutamol sulphate as a model drug). Compared to commercial lactose, crystallised lactose particles were less elongated, covered with fine lactose particles, and had a rougher surface morphology. The crystallised lactose powders had a considerably lower bulk and tap density and poorer flow when compared to commercial lactose. Engineered carrier with better flow showed improved drug content homogeneity, reduced amounts of drug "deposited" on the inhaler device and throat, and a smaller drug aerodynamic diameter upon inhalation. Aerodynamic diameter of salbutamol sulphate increased as lactose aerodynamic diameter decreased (linear, R(2)=0.9191) and/or as fine particle lactose content increased (linear, R(2)=0.8653). Improved drug aerosolisation performance in the case of crystallised lactose particles was attributed to lower drug-carrier adhesion forces due to a rougher surface and higher fine particle content. In conclusion, this work proved that using binary combinations of solvents in crystallisation medium is vital in modification of the physicochemical and micromeritic properties of carriers to achieve a desirable aerosolisation performance from DPI formulations. Among all lactose samples, lactose particles crystallised from pure butanol generated the highest overall DPI formulations desirability.

Improved aerosolization performance of salbutamol sulfate formulated with lactose crystallized from binary mixtures of ethanol-acetone

It has been shown that dry powder inhaler (DPI) formulations typically achieve low fine particle fractions (poor performance). A commonly held theory is that this is due, at least in part, to low levels of detachment of drug from lactose during aerosolization as a result of strong adhesion of drug particles to the carrier surfaces. Therefore, the purpose of the present study is to overcome poor aerosolization performance of DPI formulation by modification of lactose particles. Lactose particles were crystallized by adding solution in water to different ratios of binary mixtures of ethanol-acetone. The results showed that modified lactose particles had exceptional aerosolization performance that makes them superior to commercial lactose particles. Morphology assessment showed that crystallized lactose particles were less elongated, more irregular in shape, and composed of smaller primary lactose particles compared with commercial lactose. Solid-state characterization showed that commercial lactose particles were α-lactose monohydrate, whereas crystallized lactose particles were a mixture of α-lactose monohydrate and β-lactose according to the ratio of ethanol-acetone used during crystallization process. The enhanced performance could be mainly due to rougher surface and/or higher amounts of fines compared with the lactose crystallized from pure ethanol or commercial lactose.