Abstract
In this study, hydroxypropyl-beta-cyclodextrin (HP-β-CD) particles were produced using supercritical assisted atomization (SAA) with carbon dioxide as the spraying medium or co-solute and aqueous ethanol solution as the solvent. The effects of several key factors on the morphology and size of the HP-β-CD particles were investigated. These factors included the solvent effect, temperatures of the precipitator and saturator, concentration of the HP-β-CD solution, and flow rate ratio of carbon dioxide to the HP-β-CD solution. The conducive conditions for producing fine spherical particles were 54.2% (w/w) aqueous ethanol as the solvent; precipitator and saturator temperatures of 373.2 K and 353.2 K, respectively; a flow rate ratio of carbon dioxide to HP-β-CD solution of 1.8; and low concentrations of HP-β-CD solution. The addition of leucine (LEU) enhanced the aerosol performance of the HP-β-CD particles, and the fine particle fraction (FPF) of the HP-β-CD particles with the addition of 13.0 mass% LEU was 1.8 times higher than that of the HP-β-CD particles without LEU. This study shows that LEU can act as a dispersion enhancer and that HP-β-CD particles produced using SAA can be used as pulmonary drug carriers.
Highlights
Cyclodextrins (CDs) are cyclic oligosaccharides consisting of covalently linked glucopyranose rings
Our previous study showed that the vapor–liquid equilibrium (VLE) phase diagram of a CO2 -water-ethanol ternary mixture can be used to qualitatively estimate the phase behavior of the mixtures in the saturator [17]
The feeding lines used a mass flow ratio of CO2 to 70.3% (w/w) aqueous ethanol solution of 1.95, which was located within the two-phase region (H2 O-rich liquid phase and CO2 -rich vapor phase)
Summary
Cyclodextrins (CDs) are cyclic oligosaccharides consisting of covalently linked glucopyranose rings. CDs adopt the shape of a truncated cone, due to the chair structure of the glucopyranose units, where the hydroxyl groups are oriented to the cone exterior with the primary hydroxyl groups (hydrophobic character) of the sugar residues at the narrow edge of the cone, and the secondary hydroxyl groups at the wider edge [1]. The hydrophobic cavity of CD acts as a molecular container to entrap guest molecules to form inclusion complexes. Many advantages of drug complexes containing cyclodextrin have been reported in the literature, including increased solubility, enhanced bioavailability, improved stability, and different novel drug delivery routes [2]. The water-soluble CD derivatives of pharmaceutical interest include the hydroxypropyl derivatives of β-CD and γ-CD (HP-β-CD and HP-γ-CD), randomly methylated β-CD (RM-β-CD), and sulfobutylether β-CD (SBE-β-CD). HP-β-CD can form water-soluble complexes with poorly water-soluble drugs and can increase the drug molecule permeability and bioavailability [7,8,9]
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