Effect of shape of sodium salicylate particles on physical property and in vitro aerosol performance of granules prepared by pressure swing granulation method

Numerical Study on Particle Adhesion in Dry Powder Inhaler Device

This study investigated the particle adhesion mechanism in a capsule of dry powder inhaler (DPI) based on a combined computational fluid dynamics and discrete element method (CFD-DEM) approach. In this study, the Johnson-Kendall-Roberts (JKR) theory was selected as the adhesion force model. The simulation results corroborated the experimental results-numerous particles remained on the outlet side of the capsule, while a few particles remained on the inlet side. In the computer simulation, the modeled particles were placed in a capsule. They were quickly dispersed to both sides of the capsule, by air fed from one side of the capsule, and delivered from the air inlet side to the outlet side of the capsule. It was confirmed that vortex flows were seen at the outlet side of the capsule, which, however, were not seen at the inlet side. Numerous collisions were observed at the outlet side, while very few collisions were observed at the inlet side. These results suggested that the vortex flows were crucial to reduce the amount of residual particles in the capsule. The original capsule was then modified to enhance the vortex flow in the area, where many particles were found remaining. The modified capsule reduced the number of residual particles compared to the original capsule. This investigation suggests that the CFD-DEM approach can be a great tool for understanding the particle adhesion mechanism and improving the delivery efficiency of DPIs.

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.

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 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.

Biopharmaceutic and pharmacokinetic studies following the oral administration of sodium salicylate in oily and aqueous vehicles to rabbit

The pharmacokinetic parameters, i.e. peak concentration (c(max)); peak time (t(max)); area under the curve (AUC); elimination rate constant (k); absorption rate constant (k(a)); Drug clearance (cl(t)), and the volume of distribution (v(d)) of sodium salicylate administered in fractionated coconut oil (FCO) have been compared with that from an aqueous and glycerin vehicles using a three-way crossover study in 12 rabbits. The results of the study show that all of the pharmacokinetic parameters tested differ significantly when administered in oily rather than aqueous or glycerin vehicles. No statistically significant difference was found between any of the above mentioned parameters when comparison was made between aqueous and glycerin formulations. The results indicate that sodium salicylate is absorbed at a lower rate but to a greater extent from oily formulation. Possible reasons for these differences are discussed and is suggested, therefore, that the oily formulation might be used as a sustained release preparation.