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Development of a spray-drying method for the formulation of respirable microparticles containing ofloxacin-palladium
Francesco Palazzo1, Stefano Giovagnoli, Aurelie Schoubben
1Department of Chemistry and Technology of Drugs, Università degli Studi di Perugia, Via del Liceo 1, 06123 Perugia, Italy.
Abstract:
The purpose of this study was to produce low-releasing spray-dried polymeric microparticles (MP) useful to target alveolar macrophages in tuberculosis (TB) inhalation therapy. Ofloxacin (Ofx) was encapsulated as ofloxacin-palladium (Ofx-Pd) complex into poly DL-lactide (PLA) MP by spray-drying. Ofx-Pd was prepared according to a method previously reported. A D-optimal design was employed to optimize drug content (DC), aerodynamic diameter (d(ae)) and span. d(ae) was calculated coupling tap-density to particle size analysis. The MP were characterized by SEM, UV spectrophotometry, and DSC. In vitro drug release was performed in comparison to Ofx loaded PLA MP. The Ofx-Pd complex formed spontaneously with a 1:1 stoichiometry. Inlet temperature, drug loading and polymer concentration resulted the most influential. Optimal MP had span of 0.9, a round shape, d(ae) of 2.5 μm, and DC of 30% (w/w). DSC and SEM analyses correlated with particle size. The optimized MP formulation showed a very low release at pH 7.4 compared to spray-dried Ofx loaded MP, the release increased slightly at lower pHs. Potentially inhalable MP were obtained by an optimized spray-drying process. The very low initial drug release at physiologic pH could be useful to target alveolar macrophages and to avoid systemic exposure.
Insights
Spray-dried polymeric microparticles (MP) loaded with ofloxacin-palladium (Ofx-Pd) were developed for tuberculosis (TB) inhalation therapy. These optimized MP exhibit low initial drug release, ideal for targeting lung macrophages and minimizing systemic exposure.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
- Drug Delivery
Background:
- Tuberculosis (TB) treatment requires effective drug delivery to alveolar macrophages.
- Developing inhalable microparticles (MP) with controlled release is crucial for targeted lung therapy.
- Polymeric microparticles offer a promising platform for encapsulating anti-TB drugs.
Purpose of the Study:
- To produce low-releasing, spray-dried polymeric microparticles (MP) for targeted alveolar macrophage delivery in TB inhalation therapy.
- To encapsulate ofloxacin-palladium (Ofx-Pd) complex into poly DL-lactide (PLA) MP using spray-drying.
- To optimize MP formulation for desirable characteristics like drug content (DC), aerodynamic diameter (d(ae)), and span.
Main Methods:
- Ofx-Pd complex preparation followed by encapsulation into PLA MP via spray-drying.
- Optimization using a D-optimal design to control DC, d(ae), and span.
- Characterization using SEM, UV spectrophotometry, DSC, and in vitro drug release studies at different pH levels.
Main Results:
- The optimized MP formulation achieved a span of 0.9, round shape, d(ae) of 2.5 μm, and 30% (w/w) DC.
- SEM and DSC analyses confirmed particle characteristics and correlated with particle size.
- Optimized MP demonstrated significantly lower initial drug release at pH 7.4 compared to non-complexed ofloxacin MP, with a slight increase at lower pH.
Conclusions:
- Optimized spray-drying process yielded potentially inhalable polymeric microparticles (MP).
- The very low initial drug release at physiological pH is advantageous for targeting alveolar macrophages.
- This formulation strategy could enhance TB treatment efficacy and reduce systemic side effects.
