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Updated: Jul 1, 2026
Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles
Published on: August 28, 2015
Monosized Polymeric Microspheres Designed for Passive Lung Targeting: Biodistribution and Pharmacokinetics after
Monica Agnoletti1,2, Cristina Rodríguez-Rodríguez2,3, Sylvia N Kłodzińska1
1Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark.
Abstract:
Local as well as systemic therapy is often used to treat bacterial lung infections. Delivery of antibiotics to the vascular side of infected lung tissue using lung-targeting microspheres (MS) is a good alternative to conventional administration routes, allowing for localized high levels of antibiotics. This delivery route can also complement inhaled antibiotic therapy, especially in the case of compromised lung function. We prepared and characterized monodisperse poly(lactic-co-glycolic acid) (PLGA) MS loaded with levofloxacin using a flow-focusing glass microfluidic chip. In vitro characterization showed that the encapsulated LVX displayed a biphasic controlled release during 5 days and preserved its antibacterial activity. The MS degradation was investigated in vitro by cross-sectioning the MS using a focused ion beam scanning electron microscope and in vivo by histological examination of lung tissue from mice intravenously administered with the MS. The MS showed changes in the surface morphology and internal matrix, whereas the degradation in vivo was 3 times faster than that in vitro. No effect on the viability of endothelial and lung epithelial cells or hemolytic activity was observed. To evaluate the pharmacokinetics and biodistribution of the MS, complete quantitative imaging of the 111indium-labeled PLGA MS was performed in vivo with single-photon emission computed tomography imaging over 10 days. The PLGA MS distributed homogeneously in the lung capillaries. Overall, intravenous administration of 12 μm PLGA MS is suitable for passive lung targeting and pulmonary therapy.
Insights
Poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with levofloxacin offer a novel approach for treating bacterial lung infections. Intravenous administration of these microspheres facilitates targeted antibiotic delivery to lung capillaries, enhancing pulmonary therapy.
Area of Science:
- Biomaterials Science
- Pharmacology
- Pulmonary Medicine
Background:
- Bacterial lung infections necessitate effective antibiotic delivery strategies.
- Conventional therapies may be limited by systemic side effects and suboptimal drug concentrations.
- Targeted delivery systems, such as microspheres, offer a promising alternative for localized antibiotic administration.
Purpose of the Study:
- To develop and characterize poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with levofloxacin for pulmonary delivery.
- To evaluate the in vitro drug release, antibacterial activity, and degradation profile of the microspheres.
- To assess the in vivo pharmacokinetics, biodistribution, and biocompatibility of the PLGA microspheres in a preclinical model.
Main Methods:
- Monodisperse PLGA microspheres loaded with levofloxacin were prepared using a microfluidic chip.
- In vitro characterization included drug release studies, antibacterial assays, and degradation analysis using scanning electron microscopy.
- In vivo evaluation involved histological examination, pharmacokinetic studies, and biodistribution analysis using SPECT imaging of radiolabeled microspheres.
Main Results:
- Levofloxacin-loaded PLGA microspheres exhibited biphasic controlled release over 5 days with preserved antibacterial activity.
- In vivo degradation of microspheres was approximately three times faster than in vitro degradation.
- Microspheres demonstrated homogeneous distribution in lung capillaries, with no observed toxicity to endothelial or lung epithelial cells.
Conclusions:
- Intravenous administration of 12 μm PLGA microspheres is suitable for passive lung targeting.
- This approach enables localized high antibiotic concentrations, complementing existing pulmonary therapies.
- PLGA microspheres represent a viable drug delivery system for enhanced treatment of bacterial lung infections.
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