Inhalable Microparticles as Carriers for Pulmonary Delivery of Thymopentin-Loaded Solid Lipid Nanoparticles
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Microparticles containing solid lipid nanoparticles (SLNs) are receiving increased attention as carriers for the lung delivery of the SLNs. Thus, we aim to prepare the hybrid microparticles and thoroughly evaluate their feasibility for the pulmonary drug delivery.
The microparticles were prepared by co-spray-drying the thymopentin (TP5)-loaded SLNs with bulking agents. Thereafter, we systematically estimated the potential of the microparticles as the carriers for the pulmonary delivery of the SLNs, including the investigations of their characteristics, aerodynamic properties, pharmacokinetics and pharmacodynamics.
The spherical and hollow microparticles presented a size of 4.1 ± 0.1 μm and a low tap density of 0.175 ± 0.02 g/cm3. In addition, the microparticles showed a high aerosolization efficiency (emitted dose of 98.0% ± 1.23% and respirable fraction of 51.07% ± 1.21%). Furthermore, the SLNs could be easily recovered from the microparticles without essential changes on their characteristics and the drug release behavior. The pharmacokinetic and pharmacodynamic studies suggested that, compared to i.v. TP5 solution, the bioavailability and therapeutic efficacy of TP5 were remarkably strengthened after the pulmonary administration of the microparticles.
Taken together, we believe the microparticles were suitable for inhalation and possesed an ample potential for the pulmonary delivery of the SLNs.
KEY WORDSpulmonary delivery microparticles solid lipid nanoparticles spray-drying thymopentin
area under the curve
confocal laser scanning microscope
dry powder inhaler
high performance liquid chromatography
mean residence time
scanning electron microscopy
solid lipid nanoparticles
twin stage impinger
water in oil
water in oil in water