Preparation of Polymeric Submicron Particle-Containing Microparticles Using a 4-Fluid Nozzle Spray Drier

Redispersible spray-dried lipid-core nanocapsules intended for oral delivery: the influence of the particle number on redispersibility

This study proposes a new approach to produce easily redispersible spray-dried lipid-core nanocapsules (LNC) intended for oral administration, evaluating the influence of the particle number density of the fed sample. The proposed approach to develop redispersible spray-dried LNC formulations intended for oral route is innovative, evidencing the needing of an optimization of the initial particle number density in the liquid suspension of nanocapsules. A mixture of maltodextrin and L-leucine (90:10 w/w) was used as drying adjuvant. Dynamic light scattering, turbidimetry, determination of surface area and pore size distribution, electron microscopy and confocal Raman microscopy (CRM) were used to characterize the proposed system and to better understand the differences in the redispersion behavior. An easily aqueous redispersion of the spray-dried powder composed of maltodextrin and L-leucine (90:10 w/w) was obtained, depending on the particle number density. Their surface area decreased in the presence of LNC. CRM enabled the visualization of the spatial distribution of the different compounds in the powders affording to better understand the influence of the particle number density of the fed sample on their redispersion behavior. This study shows the need for optimizing initial particle number density in the liquid formulation to develop redispersible spray-dried LNC powders.

Dry powder inhalable formulations for anti-tubercular therapy

Tuberculosis (TB) is an intracellular infectious disease caused by the airborne bacterium, Mycobacterium tuberculosis. Despite considerable research efforts, the treatment of TB continues to be a great challenge in part due to the requirement of prolonged therapy with multiple high-dose drugs and associated side effects. The delivery of pharmacological agents directly to the respiratory system, following the natural route of infection, represents a logical therapeutic approach for treatment or vaccination against TB. Pulmonary delivery is non-invasive, avoids first-pass metabolism in the liver and enables targeting of therapeutic agents to the infection site. Inhaled delivery also potentially reduces the dose requirement and the accompanying side effects. Dry powder is a stable formulation of drug that can be stored without refrigeration compared to liquids and suspensions. The dry powder inhalers are easy to use and suitable for high-dose formulations. This review focuses on the current innovations of inhalable dry powder formulations of drug and vaccine delivery for TB, including the powder production method, preclinical and clinical evaluations of inhaled dry powder over the last decade. Finally, the risks associated with pulmonary therapy are addressed. A novel dry powder formulation with high percentages of respirable particles coupled with a cost effective inhaler device is an appealing platform for TB drug delivery.

Nanogold POxylation: towards always-on fluorescent lung cancer targeting

Gold nanoparticles (GNPs) were POxylated with fluorescent oligomers, synthesized in supercritical CO₂, and conjugated with a laminin fragment. Particle design strongly impacts on probes uptake by the A549 cell line.

Application of a novel 3-fluid nozzle spray drying process for the microencapsulation of therapeutic agents using incompatible drug-polymer solutions

The aim of this study was to evaluate a novel 3-fluid concentric nozzle (3-N) spray drying process for the microencapsulation of omeprazole sodium (OME) using Eudragit L100 (EL100). Feed solutions containing OME and/or EL100 in ethanol were assessed visually for OME stability. Addition of OME solution to EL100 solution resulted in precipitation of OME followed by degradation of OME reflected by a colour change from colourless to purple and brown. This was related to the low pH of 2.8 of the EL100 solution at which OME is unstable. Precipitation and progressive discoloration of the 2-fluid nozzle (2-N) feed solution was observed over the spray drying time course. In contrast, 3-N solutions of EL100 or OME in ethanol were stable over the spray drying period. Microparticles prepared using either nozzle showed similar characteristics and outer morphology however the internal morphology was different. DSC showed a homogenous matrix of drug and polymer for 2-N microparticles while 3-N microparticles had defined drug and polymer regions distributed as core and coat. The results of this study demonstrate that the novel 3-N spray drying process can allow the microencapsulation of a drug using an incompatible polymer and maintain the drug and polymer in separate regions of the microparticles.

Development of a novel and customizable two-solution mixing type spray nozzle for one-step preparation of nanoparticle-containing microparticles

Production of drug nanoparticles is an effective strategy to enhance solubility and oral absorption of water-insoluble drugs. The handling of drug nanoparticles has been an important issue in drug formulation because nanoparticles easily aggregate each other and redispersion of these particles is very difficult. In the present study, we developed a unique two-solution mixing type spray nozzle that can prepare drug nanoparticles in microparticles in one step without any common solvent and surfactant, and then, the prepared formulation were evaluated. Ethylcellulose (EC) and mannitol (MAN) were used as a model polymer of water-insoluble compound and a water-soluble carrier, respectively. We characterized the EC/MAN microparticles produced by the novel spray nozzle when customizing the nozzle parts to mix EC and MAN solution. Relatively smaller EC nanoparticles (<110 nm) in MAN microparticles (approximately 3 µm) were obtained by changing the customizable parts in the nozzle. In addition, the core of EC nanoparticles (<50 nm) was also observed by atomic force microscopy. We also found that the mixing time in the nozzle parts affected the size and the standard deviation of EC nanoparticles. These results suggest that the size of EC nanoparticles in MAN microparticles is controllable by using this unique nozzle. After all, we could prepare MAN microparticles containing EC nanoparticles in one step by using the novel nozzle. The drug/MAN microparticles formulation produced by the nozzle may be useful for the handling of drug nanoparticles.

Improved bioavailability of a water-insoluble drug by inhalation of drug-containing maltosyl-β-cyclodextrin microspheres using a four-fluid nozzle spray drier

We previously developed a unique four-fluid nozzle spray drier that can produce water-soluble microspheres containing water-insoluble drug nanoparticles in one step without any common solvent between the water-insoluble drug and water-soluble carrier. In the present study, we focused on maltosyl-β-cyclodextrin (malt-β-CD) as a new water-soluble carrier and it was investigated whether drug/malt-β-CD microspheres could improve the bioavailability compared with our previously reported drug/mannitol (MAN) microspheres. The physicochemical properties of bare drug microparticles (ONO-2921, a model water-insoluble drug), drug/MAN microspheres, and drug/malt-β-CD microspheres were evaluated. In vitro aerosol performance, in vitro dissolution rate, and the blood concentration profiles after intratracheal administration were compared between these formulations. The mean diameter of both drug/MAN and drug/malt-β-CD microspheres was approximately 3-5 μm and both exhibited high aerosol performance (>20% in stages 2-7), but drug/malt-β-CD microspheres had superior release properties. Drug/malt-β-CD microspheres dissolved in an aqueous phase within 2 min, while drug/MAN microspheres failed to dissolve in 30 min. Inhalation of drug/malt-β-CD microspheres enhanced the area under the curve of the blood concentration curve by 15.9-fold than that of bare drug microparticles and by 6.1-fold than that of drug/MAN microspheres. Absolute bioavailability (pulmonary/intravenous route) of drug/malt-β-CD microspheres was also much higher (42%) than that of drug/MAN microspheres (6.9%). These results indicate that drug/malt-β-CD microspheres prepared by our four-fluid nozzle spray drier can improve drug solubility and pulmonary delivery.

Combination therapy of surgical tumor resection with implantation of a hydrogel containing camptothecin-loaded poly(lactic-co-glycolic acid) microspheres in a C6 rat glioma model

We have developed a drug-loaded poly(lactic-co-glycolic acid) (PLGA) microsphere-containing thermoreversible gelation polymer (TGP) (drug/PLGA/TGP) formulation as a novel device for implantation after surgical glioma resection. TGP is a thermosensitive polymer that is a gel at body temperature and a sol at room temperature. When a drug/PLGA/TGP formulation is injected into a target site, PLGA microspheres in TGP gel localize at the injection site and do not diffuse across the entire brain tissue, and thus, sustained drug release from the PLGA microspheres at the target site is expected. Using in vivo imaging, we confirmed that the implantation of indocyanine green (ICG)/PLGA/TGP formulation exhibited a stronger localization of ICG at the injection site 28 d after injection compared with that of ICG/PLGA formulation. The therapeutic effect (mean survival) was evaluated in a C6 rat glioma model. Surgical tumor resection alone showed almost no effect on survival (controls, 18 d; surgical resection; 18.5 d). Survival was prolonged after the treatment with a camptothecin (CPT; 10 µg)/PLGA/TGP formulation (24 d). The combination treatment of surgical tumor resection and CPT/PLGA/TGP showed almost the same therapeutic effect (24 d) compared with CPT/PLGA/TGP alone, while the combination treatment produced long term survivors (>60 d). Therefore, the CPT/PLGA/TGP formulation can be an effective candidate for localized and sustained long-term glioma therapy.

Selection of excipient, solvent and packaging to optimize the performance of spray-dried formulations: case example fenofibrate

CONTEXT

Along with other options, solid dispersions prepared by spray drying offer the possibility of formulating poorly soluble drugs in a rapidly dissolving format. As a wide range of potential excipients and solvents is available for spray drying, it is usually necessary to carry out a comprehensive array of studies to arrive at an optimal formulation.

OBJECTIVE

To study the influence of formulation parameters such as co-sprayed excipients, solvents and packaging on the manufacture, in vitro performance and stability of spray-dried oral drug products using fenofibrate as a model drug.

MATERIALS AND METHODS

Solid dispersions of fenofibrate with different amorphous polymers were manufactured from two solvent systems by spray drying. These were characterized in terms of physicochemical properties, crystalline content and dissolution behavior in biorelevant media upon production and after storage in two packaging systems (Glass and Activ-Vials(™)).

RESULTS AND DISCUSSION

Spray drying the same formulation from two different solvents led to different physicochemical properties, dissolution behavior and long-term stability. The dissolution behavior and long-term stability also varied significantly among excipients. The viscosity of the polymer and the packaging material proved to be important to the long-term stability.

CONCLUSION

For spray-dried products containing fenofibrate, the excipients were ranked according to dissolution and stability performance as follows: PVP derivatives >> HPMC 2910/15, HPMCAS-MF, HP-β-CD >> PVP:PVA 2:8. EtOH 96% proved superior to acetone/water for spray drying with polymers. The results were used to propose a general approach to developing spray-dried formulations of poorly soluble drugs.

Early development drug formulation on a chip: fabrication of nanoparticles using a microfluidic spray dryer

Early development drug formulation is exacerbated by increasingly poor bioavailability of potential candidates. Prevention of attrition due to formulation problems necessitates physicochemical analysis and formulation studies at a very early stage during development, where the availability of a new substance is limited to small quantities, thus impeding extensive experiments. Miniaturization of common formulation processes is a strategy to overcome those limitations. We present a versatile technique for fabricating drug nanoformulations using a microfluidic spray dryer. Nanoparticles are formed by evaporative precipitation of the drug-loaded spray in air at room temperature. Using danazol as a model drug, amorphous nanoparticles of 20-60 nm in diameter are prepared with a narrow size distribution. We design the device with a geometry that allows the injection of two separate solvent streams, thus enabling co-spray drying of two substances for the production of drug co-precipitates with tailor-made composition for optimization of therapeutic efficiency.

Spray drying technique: II. Current applications in pharmaceutical technology

This review presents current applications of spray drying in pharmaceutical technology. The topics discussed include the obtention of excipients and cospray dried composites, methods for increasing the aqueous solubility and bioavailability of active substances, and modified release profiles from spray-dried particles. This review also describes the use of the spray drying technique in the context of biological therapies, such as the spray drying of proteins, inhalable powders, and viable organisms, and the modification of the physical properties of dry plant extracts.

Application of a four-fluid nozzle spray drier to prepare inhalable rifampicin-containing mannitol microparticles

The purpose of this study was to use a four-fluid nozzle spray drier as a new one-step method for preparing rifampicin (RFP)-containing mannitol microparticles. A RFP-acetone/methanol (2:1) solution and aqueous solutions of mannitol (MAN) were simultaneously supplied through different liquid passages of a four-fluid nozzle spray drier and then dried to obtain MAN microparticles containing RFP. Using a cascade impactor, the in vitro aerosol performance of RFP powder and RFP-MAN microparticles with 1:5, 1:10, and 1:20 ratios was compared. The in vivo retention of RFP in the lungs of rats after intratracheal administration of 1:20 RFP-MAN microparticles was also compared. The RFP-MAN microparticles had better aerosol performance than RFP powder and delivery to the lung stages improved as the fraction of MAN was increased. For the 1:20 RFP-MAN microparticles, deposition in stages 2-7 was approximately 43%, which is sufficient for treatment. Approximately 8% of the RFP-MAN microparticles were deposited in stages 6-7, which corresponds to alveoli containing alveolar macrophages. The initial retention of RFP in the lung following pulmonary delivery of 1:20 RFP-MAN microparticles was higher than following oral or intravenous administration of RFP, but the elimination was rapid, resulting in the disappearance of RFP from the lung within 4 h. The plasma concentration-time profile of RFP after intratracheal administration of 1:20 RFP-MAN microparticles was consistent with the profile for RFP retention in the lung. Addition of cholesterol or phosphatidylcholine to RFP had little effect on its retention in the lung. The RFP-MAN microparticles were effective for delivery of RFP to the lung, but the RFP rapidly removed from the lung into the blood circulation. This study demonstrated that RFP-containing MAN microparticles prepared in one step using the four-fluid nozzle spray drier efficiently deliver RFP to the lung, although methods must be developed to prolong its retention and improve targeting to alveolar macrophages.

Preparation of functional composite particles of salbutamol sulfate using a 4-fluid nozzle spray-drying technique

A previous study on spray-drying demonstrated that it could promote the solubility of poorly water-soluble drugs using water-soluble polymers. Here, the preparation of composite particles of salbutamol sulfate (Sb) with water-insoluble polymers, such as Eudragit RS (RS) or Eudragit RL (RL) as a carrier, was examined. Despite the water insolubility of both polymers, the permeability of water was low in the former but high in the latter. We attempted to prepare controlled release composite particles by exploiting the characteristics of these carriers. The composite particles of the three components (Sb, RS, and RL) were prepared using a 4-fluid nozzle spray-dryer, and their physico-chemical and dissolution properties were compared with physical mixtures. Examination of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray-drying process had atomized to several microns and were spherical. Analysis by X-ray diffraction and differential scanning calorimetry revealed that diffraction peaks and heat of fusion of Sb in the spray-dried samples decreased, indicating that the drug was amorphous and formed a solid dispersion. FT-IR analysis suggested that the amino group of Sb and a carbonyl group of the polymers formed a hydrogen bond. A dissolution test of Sb-RS-RL particles prepared using the 4-fluid nozzle spray-drying method showed that release rates were depressed significantly compared to the physical mixture at pH 1.2 and 6.8, and the depression was greater when RS was used instead of RL, presumably because of the permeability difference. The compression of these particles into tablets revealed that desirable controlled released dosage forms could be prepared. In addition, Sb was used to simulate an anti-asthmatic drug. For this an Andersen cascade impactor for dry powder inhalers was used to investigate delivery to the lungs.

Composition of PLGA and PEI/DNA nanoparticles improves ultrasound-mediated gene delivery in solid tumors in vivo

The goal of this study was to enhance gene delivery and tumor cell transfection in vivo by using a combination of ultrasonication with complex nanoparticles consisting of two types of nanoparticles: PEI/DNA beta-gal plasmid with highly positive zeta-potential and air-filled poly (lactic-co-glycolic acid) (PLGA) particles (with negative zeta-potential) manufactured in our laboratory. The PLGA/PEI/DNA nanoparticles were a colloid with positive zeta-potential and injected i.v. in nude mice with DU145 human prostate tumors. We found that the combination of PLGA/PEI/DNA nanoparticles with ultrasonication substantially enhanced tumor cell transfection in vivo. The overexpression of beta-gal gene was evaluated histochemically and by Western blot analysis. At least an 8-fold increase of the cell transfection efficacy was obtained in irradiated tumors compared to non-irradiated controls, while little to no cell death was produced by ultrasonication.

Pharmaceutical particle engineering via spray drying

This review covers recent developments in the area of particle engineering via spray drying. The last decade has seen a shift from empirical formulation efforts to an engineering approach based on a better understanding of particle formation in the spray drying process. Microparticles with nanoscale substructures can now be designed and their functionality has contributed significantly to stability and efficacy of the particulate dosage form. The review provides concepts and a theoretical framework for particle design calculations. It reviews experimental research into parameters that influence particle formation. A classification based on dimensionless numbers is presented that can be used to estimate how excipient properties in combination with process parameters influence the morphology of the engineered particles. A wide range of pharmaceutical application examples—low density particles, composite particles, microencapsulation, and glass stabilization—is discussed, with specific emphasis on the underlying particle formation mechanisms and design concepts.

Preparation of drug nanoparticle-containing microparticles using a 4-fluid nozzle spray drier for oral, pulmonary, and injection dosage forms

We prepared microparticles containing nanoparticles of water-insoluble pranlukast hemihydrate (PLH) using a 4-fluid nozzle spray drier. These particles were designed to improve the absorption of PLH and to allow delivery by oral, pulmonary, and injection routes. Mannitol (MAN) was used as a water-soluble carrier for the microparticles. We orally administered suspensions of PLH powder and PLH-MAN microparticles to rats. We also compared the in vitro aerosol performance of the PLH powder and PLH-MAN microparticles using a cascade impactor, and we compared the delivery of PLH by oral administration of PLH powder and pulmonary delivery of PLH-MAN microparticles at PLH/MAN ratios of 1:4 and 1:10. The absorption of PLH was markedly enhanced by pulmonary deliver of PLH-MAN composite microparticles. The area under the plasma concentration-time curve per dose for pulmonary administration of the 1:4 and 1:10 PLH-MAN microparticles was approximately 85- and 100-fold higher, respectively, than for oral administration of PLH powder. Also, we found that PLH rapidly disappeared from the plasma following injection of PLH aqueous solution or PLH-MAN microparticles dissolved in water. The PLH particles remaining after dissolution of MAN from the 1:10 PLH-MAN microparticles were 200 nm in diameter. Therefore, PLH particles may be captured immediately after injection by reticuloendothelial tissues such as the liver and spleen. This study demonstrated that it is possible to use the 4-fluid spray drier to prepare microparticles containing PLH nanoparticles that that improve drug absorption and can be administered by oral, pulmonary, and injection routes.

One-step preparation of drug-containing microparticles to enhance the dissolution and absorption of poorly water-soluble drugs using a 4-fluid nozzle spray drier

We studied the use of a 4-fluid nozzle spray drier as a new one-step method for preparing drug-containing microparticles to enhance the dissolution and absorption of poorly water-soluble drugs. We employed ethenzamide (EZ) and flurbiprofen (FP) as poorly water-soluble drugs and lactose (LAC) and mannitol (MAN) as water-soluble carriers for microparticles. EZ-ethanol or FP-acetone/methanol (2:1) solutions and aqueous solutions of LAC or MAN were simultaneously supplied through different liquid passages of a 4-fluid nozzle spray drier and then dried to obtain LAC or MAN microparticles containing EZ or FP. The dissolution of EZ from the EZ/LAC and EZ/MAN microparticles was much faster than that from EZ powder. The dissolution of EZ was more rapid from the EZ/MAN microparticles than the EZ/LAC microparticles. The dissolution of FP from the FP/MAN microparticles was greatly enhanced because of large effective surface area of FP dispersed in microparticles following rapid dissolution of MAN. The absorption of FP after oral administration of the FP/MAN microparticles to rats was markedly increased. The results demonstrate that the 4-fluid nozzle spray drier can be used for the one-step preparation of drug-containing microparticles that enhance the dissolution and absorption of poorly water-soluble drugs and that overcome the problem of finding a common solvent for drugs and carriers.

Particle Engineering for Pulmonary Drug Delivery

With the rapidly growing popularity and sophistication of inhalation therapy, there is an increasing demand for tailor-made inhalable drug particles capable of affording the most efficient delivery to the lungs and the most optimal therapeutic outcomes. To cope with this formulation demand, a wide variety of novel particle technologies have emerged over the past decade. The present review is intended to provide a critical account of the current goals and technologies of particle engineering for the development of pulmonary drug delivery systems. These technologies cover traditional micronization and powder blending, controlled solvent crystallization, spray drying, spray freeze drying, particle formation from liquid dispersion systems, supercritical fluid processing and particle coating. The merits and limitations of these technologies are discussed with reference to their applications to specific drug and/or excipient materials. The regulatory requirements applicable to particulate inhalation products are also reviewed briefly.