Effect of carrier morphology and surface characteristics on the development of respirable PLGA microcapsules for sustained-release pulmonary delivery of insulin

Oral insulin delivery: Barriers, strategies, and formulation approaches: A comprehensive review

Diabetes Mellitus is characterized by a hyperglycemic condition which can either be caused by the destruction of the beta cells or by the resistance developed against insulin in the cells. Insulin is a peptide hormone that regulates the metabolism of carbohydrates, proteins, and fats. Type 1 Diabetes Mellitus needs the use of Insulin for efficient management. However invasive methods of administration may lead to reduced adherence by the patients. Hence there is a need for a non-invasive method of administration. Oral Insulin has several merits over the conventional method including patient compliance, and reduced cost, and it also mimics endogenous insulin and hence reaches the liver by the portal vein at a higher concentration and thereby showing improved efficiency. However oral Insulin must pass through several barriers in the gastrointestinal tract. Some strategies that could be utilized to bypass these barriers include the use of permeation enhancers, absorption enhancers, use of suitable polymers, use of suitable carriers, and other agents. Several formulation types have been explored for the oral delivery of Insulin like hydrogels, capsules, tablets, and patches which have been described briefly by the article. A lot of attempts have been made for developing oral insulin delivery however none of them have been commercialized due to numerous shortcomings. Currently, there are several formulations from the companies that are still in the clinical phase, the success or failure of some is yet to be seen in the future.

A Novel 3D Printing Particulate Manufacturing Technology for Encapsulation of Protein Therapeutics: Sprayed Multi Adsorbed-Droplet Reposing Technology (SMART)

Recently, various innovative technologies have been developed for the enhanced delivery of biologics as attractive formulation targets including polymeric micro and nanoparticles. Combined with personalized medicine, this area can offer a great opportunity for the improvement of therapeutics efficiency and the treatment outcome. Herein, a novel manufacturing method has been introduced to produce protein-loaded chitosan particles with controlled size. This method is based on an additive manufacturing technology that allows for the designing and production of personalized particulate based therapeutic formulations with a precise control over the shape, size, and potentially the geometry. Sprayed multi adsorbed-droplet reposing technology (SMART) consists of the high-pressure extrusion of an ink with a well determined composition using a pneumatic 3D bioprinting approach and flash freezing the extrudate at the printing bed, optionally followed by freeze drying. In the present study, we attempted to manufacture trypsin-loaded chitosan particles using SMART. The ink and products were thoroughly characterized by dynamic light scattering, rheometer, Scanning Electron Microscopy (SEM), and Fourier Transform Infra-Red (FTIR) and Circular Dichroism (CD) spectroscopy. These characterizations confirmed the shape morphology as well as the protein integrity over the process. Further, the effect of various factors on the production were investigated. Our results showed that the concentration of the carrier, chitosan, and the lyoprotectant concentration as well as the extrusion pressure have a significant effect on the particle size. According to CD spectra, SMART ensured Trypsin's secondary structure remained intact regardless of the ink composition and pressure. However, our study revealed that the presence of 5% (w/v) lyoprotectant is essential to maintain the trypsin's proteolytic activity. This study demonstrates, for the first time, the viability of SMART as a single-step efficient process to produce biologics-based stable formulations with a precise control over the particulate morphology which can further be expanded across numerous therapeutic modalities including vaccines and cell/gene therapies.

Classification of scanning electron microscope images of pharmaceutical excipients using deep convolutional neural networks with transfer learning

Convolutional Neural Networks (CNNs) are image analysis techniques that have been applied to image classification in various fields. In this study, we applied a CNN to classify scanning electron microscopy (SEM) images of pharmaceutical raw material powders to determine if a CNN can evaluate particle morphology. We tested 10 pharmaceutical excipients with widely different particle morphologies. SEM images for each excipient were acquired and divided into training, validation, and test sets. Classification models were constructed by applying transfer learning to pretrained CNN models such as VGG16 and ResNet50. The results of a 5-fold cross-validation showed that the classification accuracy of the CNN model was sufficiently high using either pretrained model and that the type of excipient could be classified with high accuracy. The results suggest that the CNN model can detect differences in particle morphology, such as particle size, shape, and surface condition. By applying Grad-CAM to the constructed CNN model, we succeeded in finding particularly important regions in the particle image of the excipients. CNNs have been found to have the potential to be applied to the identification and characterization of raw material powders for pharmaceutical development.

Synthesis, Characterization and In Vitro Evaluation of Chitosan Nanoparticles Physically Admixed with Lactose Microspheres for Pulmonary Delivery of Montelukast

This study aimed to synthesise montelukast-loaded polymeric nanoparticles via the ionic gelation method using chitosan as a natural polymer and tripolyphosphate as a crosslinking agent. Tween 80, hyaluronic acid and leucine were added to modify the physicochemical properties of nanoparticles, reduce the nanoparticles’ uptake by alveolar macrophages and improve powder aerosolisation, respectively. The nanoparticles ranged from 220 nm to 383 nm with a polydispersity index of ≤0.50. The zeta potential of nanoparticles ranged from 11 mV to 22 mV, with a drug association efficiency of 46–86%. The simple chitosan nanoparticles (F2) were more spherical in comparison to other formulations (F4–F6), while the roughness of hyaluronic acid (F5) and leucine (F6) added formulations was significantly high er than F2 and Tween 80 added formulation (F4). The DSC and FTIR analysis depict that the physical and chemical properties of the drug were preserved. The release of the drugs from nanoparticles was more sustained in the case of F5 and F6 when compared to F2 and F4 due to the additional coating of hyaluronic acid and leucine. The nanoparticles were amorphous and cohesive and prone to exhalation due to their small size. Therefore, nanoparticles were admixed with lactose microspheres to reduce particle agglomeration and improve powder dispersion from a dry powder inhaler (DPI). The DPI formulations achieved a dispersed fraction of 75 to 90%, a mass median aerodynamic diameter (MMAD) of 1–2 µm and a fine particle fraction (FPF) of 28–83% when evaluated using the Anderson cascade impactor from Handihaler®. Overall, the montelukast-loaded nanoparticles physically admixed with lactose microspheres achieved optimum deposition in the deep lung for potential application in asthmatic patients.

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.

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.

Wrinkling Non-Spherical Particles and Its Application in Cell Attachment Promotion

Surface wrinkled particles are ubiquitous in nature and present in different sizes and shapes, such as plant pollens and peppercorn seeds. These natural wrinkles provide the particles with advanced functions to survive and thrive in nature. In this work, by combining flow lithography and plasma treatment, we have developed a simple method that can rapidly create wrinkled non-spherical particles, mimicking the surface textures in nature. Due to the oxygen inhibition in flow lithography, the non-spherical particles synthesized in a microfluidic channel are covered by a partially cured polymer (PCP) layer. When exposed to plasma treatment, this PCP layer rapidly buckles, forming surface-wrinkled particles. We designed and fabricated various particles with desired shapes and sizes. The surfaces of these shapes were tuned to created wrinkle morphologies by controlling UV exposure time and the washing process. We further demonstrated that wrinkles on the particles significantly promoted cell attachment without any chemical modification, potentially providing a new route for cell attachment for various biomedical applications.

Aggregated Nanotransfersomal Dry Powder Inhalation of Itraconazole for Pulmonary Drug Delivery

PURPOSE

Local therapy is a valuable and strategic approach in the treatment of lung associated diseases and dry powder inhalation (DPI) formulations play the key role in this plan. Transfersome has been introduced as a novel biocompatible vesicular system with potential for administration in pulmonary drug delivery. The present study was designed to prepare Itraconazole-loaded nanotrantransfersomal DPI formulation.

METHODS

Itraconazole-loaded nanotransfersomes with three different types of surfactant in varying concentrations were prepared and characterized in the point of particle size distribution and morphology by laser light scattering and scanning electron microscopy (SEM) methods. The optimized transferosomal formulations were co-spray dried with mannitol and the aerosolization efficiency and aerodynamic properties of dry powders were determined by next generation impactor using a validated HPLC technique.

RESULTS

The volume mean diameter of optimized nanotransfersomal formulation with lecithin:Span® 60 in the ratio of 90:10 was 171 nm with narrow size distribution pattern which increased up to 518 nm after drug loading. Different types of surfactant did not influence the particle size significantly. SEM images confirmed the formation of aggregated nanoparticles in the suitable range (1-5 µm) for the pulmonary drug delivery. Aerosolization evaluation of co-spray dried formulations with different amounts of mannitol indicated that 2:1 ratio of mannitol:transfersome (w:w) showed the best aerosolization efficiency (fine particle fraction (FPF)=37%). Increasing of mannitol significantly decreased the FPF of the optimized formulations.

CONCLUSION

The results of this study was introduced the potential application of nanotransfersomes in the formulation of DPIs for lung delivery of various drugs.

Physicochemical characterization of spray-dried PLGA/PEG microspheres, and preliminary assessment of biological response

CONTEXT

The use of spray-drying to prepare blended PLGA:PEG microspheres with lower immune detection.

OBJECTIVE

To study physical properties, polymer miscibility and alveolar macrophage response for blended PLGA:PEG microspheres prepared by a laboratory-scale spray-drying process.

METHODS

Microspheres were prepared by spray-drying 0-20% w/w ratios of PLGA 65:35 and PEG 3350 in dichloromethane. Particle size and morphology was studied using scanning electron microscopy. Polymer miscibility and residual solvent levels evaluated by thermal analysis (differential scanning calorimetry - DSC and thermogravimetric analysis - TGA). Immunogenicity was assessed in vitro by response of rat alveolar macrophages (NR8383) by the MTT-based cell viability assay and reactive oxygen species (ROS) detection.

RESULTS

The spray dried particles were spherical, with a size range of about 2-3 µm and a yield of 16-60%. Highest yield was obtained at 1% PEG concentration. Thermal analysis showed a melting peak at 59 °C (enthalpy: 170.61 J/g) and a degradation-onset of 180 °C for PEG 3350. PLGA 65:35 was amorphous, with a Tg of 43 °C. Blended PLGA:PEG microspheres showed a delayed degradation-onset of 280 °C, and PEG enthalpy-loss corresponding to 15% miscibility of PEG in PLGA. NR8383 viability studies and ROS detection upon exposure to these cells suggested that blended PLGA:PEG microspheres containing 1 and 5% PEG are optimal in controling cell proliferation and activation.

CONCLUSION

This research establishes the feasibility of using a spray-drying process to prepare spherical particles (2-3 µm) of molecularly-blended PLGA 65:35 and PEG 3350. A PEG concentration of 1-5% was optimal to maximize process yield, with minimal potential for immune detection.

How to overcome the limitations of current insulin administration with new non-invasive delivery systems

Non-invasive insulin delivery systems have potential to overcome the most pressing problem regarding effective treatment of diabetic patients: therapy compliance. To overcome this disadvantage, non-invasive routes such as oral, buccal, pulmonary, nasal and transdermal have been proposed. These new routes of insulin administration may help to suppress hypoglycemia episodes and aid to control weight gain and post-meal glucose. Despite all efforts the invasive route remains preferential, since studies on insulin administration by non-invasive routes conducted to date have not demonstrated clinical efficacy and safety, including some products introduced in the market. Therefore, the aim of this review is to make an update of the current state of administration of insulin by non-invasive routes as alternatives to the conventional invasive route.

Impact of surfactant selection on the formulation and characterization of microparticles for pulmonary drug delivery

The effect of suspension stabilizers, internal aqueous phase volume and polymer amount were investigated for the production of protein loaded poly(d,l lactide-co-glycolide) (PLGA) microparticles suitable for pulmonary drug delivery. PLGA microparticles were produced adopting water-in-oil-in-water (W/O/W) solvent evaporation technique and were investigated for surface morphology, particle size, encapsulation efficiency (EE%) and in-vitro release profile. Porous surface morphologies with a narrow size distribution were observed when employing 0.5 ml internal aqueous phase; 23.04 µm (± 0.98), 15.05 µm (± 0.27) and 22.89 µm (±0.41) for PVA, Tween 80 and oleic acid. Porous microparticles exhibited increased size and reduction in EE% with increasing internal aqueous phase, with non-porous microparticles produced when adopting 2.0 ml internal aqueous phase. The selection of stabilizer influences the size of the pores formed thus offers potential for the aerodynamic properties of the microparticles to be manipulated to achieve suitable aerosolization characteristics for pulmonary delivery of proteins.

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.

Further experimentation of inhaled; LANTUS, ACTRAPID and HUMULIN with todays' production systems

BACKGROUND

Several aerosol production systems have been used for aerosol insulin production. However; since the first studies several new models of jet-nebulizers and ultrasound nebulizers have been introduced in the market.

MATERIALS AND METHODS

Three different models of jet-nebulizers (different brands, same properties) and three different ultrasound nebulizers (different brands, same properties). Six residual cups (2 small ≤ 6 ml and 3 large ≤ 8 ml) were used for the jet-nebulizers. The ultrasound nebulizers were used with their facemasks or with their inlets which were included in the purchase package.

RESULTS

Ultrasound nebulizers; LANTUS produces by far the lowest mean droplets (2.44) half the size of the other two drugs (4.43=4.97). GIMA nebulizer is the most efficient producing one third of the droplet size of SHIMED and one second of EASYNEB (2.06<3.15<6.62). Finally, the 4 ml loading concentration is more suitable for supporting the production of smaller droplets (3.65<4.24). Drugs and nebulizers act interactively yielding very large droplets when ACTRAPID and HUMULIN are administered in joint with SHIMED nebulizer (9.59=7.72). Jet-nebulizers; HUMULIN again is the least preferred insulin since it hardly reaches the low but equal performance of others at the loading level of 6 ml. Residual cups E and B produce uniquely lower mean droplets at loading level 6.

CONCLUSIONS

Ultrasound nebulizers; the best suggested combination should be LANTUS insulin, GIMA nebulizer administered at loading dose of 4 ml jet-nebulizers. A global review can give the best combination: the lowest mean droplets are produced when the drugs LANTUS (mostly) and ACTRAPID are administered, applying the SUNMIST nebulizer in concert with residual cup B at loading levels of 6 ml.

Dry powder cationic lipopolymeric nanomicelle inhalation for targeted delivery of antitubercular drug to alveolar macrophage

Excipients having self-assembling properties are less explored in the field of dry powder inhalation (DPI) technology. An amphiphilic lipopolymer system was developed using stearic acid (SA) and branched polyethyleneimine (BPEI) (1800 Dalton), at different proportions by covalent conjugation. A molecular dynamic (MD) simulation tool was employed for predicting the carrier behavior in a polar in vivo condition. The structural characterization was carried out using nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared (FTIR) spectroscopy. The physical nature of the lipopolymer was analyzed by differential scanning calorimetry. Determination of zeta potential and diameter of the micelles showed existence of cationic particles in the nano size range when a lower number of primary amino groups of BPEI was grafted with SA. The rifampicin (RIF)-loaded lipopolymer was also formulated further into spray-dried microparticles. Powder X-ray diffraction (PXRD) studies revealed that the RIF API (active pharmaceutical ingredient) exists as molecular dispersion in spray-dried microparticles. Topological analysis of the spray-dried nanomicelle was carried out using scanning electron microscopy (SEM). A large population of the drug-carrying particles were found to be under the inhalable size range (fine particle fraction 67.88% ± 3%). In vitro drug release kinetics from spray-dried nanomicelles were carried out at lung fluid pH.

Lactose engineering for better performance in dry powder inhalers

Dry powder inhaler (DPI) is generally formulated as a powder mixture of coarse carrier particles and micronized drug with aerodynamic diameters of 1-5 μm. Carrier particles are used to improve drug particle flowability, thus improving dosing accuracy, minimizing the dose variability compared with drug alone and making them easier to handle during manufacturing operations. Lactose is the most common and frequently used carrier in DPIs formulations and nowadays various inhalation grades of lactose with different physico-chemical properties are available on the market. Therefore, the purpose of this manuscript is to review evolution of lactose as a carrier in inhalable formulations, their production and the impact of its physico-chemical properties on drug dispersion. This review offers a perspective on the current reported studies to modify lactose for better performance in DPIs.

Engineered PLGA nano- and micro-carriers for pulmonary delivery: challenges and promises

Objectives

The aim of this review is to summarize the current state-of-the-art in poly(lactic-co-glycolic acid) (PLGA) carriers for inhalation. It presents the rational of use, the potential and the recent advances in developing PLGA microparticles and nanoparticles for pulmonary delivery. The most promising particle engineering strategies are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

Key findings

Biodegradable polymer carriers, such as PLGA particles, may permit effective protection and long-term delivery of the inhaled drug and, when adequately engineered, its efficient transport to the target. The carrier can be designed for inhalation on the basis of several strategies through the adequate combination of available particle technologies and excipients. In so doing, the properties of PLGA particles can be finely tuned at micro-size and nano-size level to fulfill specific therapeutic needs. This means not only to realize optimal in vitro/in vivo lung deposition of the formulation, which is still crucial, but also to control the fate of the drug in the lung after particle landing.

Summary

Although many challenges still exist, PLGA carriers may be highly beneficial and present a new scenario for patients suffering from chronic lung diseases and for pharmaceutical companies working to develop novel inhaled products.

A rapid-acting, long-acting insulin formulation based on a phospholipid complex loaded PHBHHx nanoparticles

The application of poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) for sustained and controlled delivery of hydrophilic insulin was made possible by preparing insulin phospholipid complex loaded biodegradable PHBHHx nanoparticles (INS-PLC-NPs). The INS-PLC-NPs produced by a solvent evaporation method showed a spherical shape with a mean particle size, zeta potential and entrapment efficiency of 186.2 nm, -38.4 mv and 89.73%, respectively. In vitro studies demonstrated that only 20% of insulin was released within 31 days with a burst release of 5.42% in the first 8 h. The hypoglycaemic effect in STZ induced diabetic rats lasted for more than 3 days after the subcutaneous injection of INS-PLC-NPs, which significantly prolonged the therapeutic effect compared with the administration of insulin solution. The pharmacological bioavailability (PA) of INS-PLC-NPs relative to insulin solution was over 350%, indicating that the bioavailability of insulin was significantly enhanced by INS-PLC-NPs. Therefore, the INS-PLC-NPs system is promising to serve as a long lasting insulin release formulation, by which the patient compliance can be enhanced significantly. This study also showed that phospholipid complex loaded biodegradable nanoparticles (PLC-NPs) have a great potential to be used as a sustained delivery system for hydrophilic proteins to be encapsulated in hydrophobic polymers.

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.