Abstract 

Pulmonary administration of antibiotics using dry powder inhalers (DPIs) represents an attractive strategy for the localized treatment of respiratory infections. This route of delivery allows high drug concentrations to be achieved directly at the site of infection while minimizing systemic exposure. Ciprofloxacin, a broad-spectrum fluoroquinolone antibiotic, has been widely investigated as a candidate for inhalation therapy. In carrier-based DPI formulations, lactose monohydrate is frequently used to enhance powder flowability, improve dose uniformity, and facilitate drug dispersion during inhalation.

The present study focused on the in vitro evaluation of aerosolization behavior and deposition characteristics of binary powder systems composed of ciprofloxacin and lactose. Powder blends were prepared using geometric mixing at a drug-to-carrier mass ratio of 2:1. The resulting formulations were filled into hard gelatin capsules and aerosolized using a Cyclohaler® capsule-based dry powder inhaler.

Aerodynamic particle size distribution was determined using a Next Generation Impactor (NGI) operated under controlled airflow conditions simulating different patient inspiratory efforts. The emitted dose was measured using a Dosage Unit Sampling Apparatus (DUSA). Quantitative determination of ciprofloxacin recovered from impactor stages and collection filters was carried out using a validated ultra-performance liquid chromatography (UPLC) method.

The tested formulations demonstrated consistent emission and effective aerosol generation. The emitted dose exceeded 70% of the nominal dose under all tested airflow conditions, indicating efficient powder release from the capsules and adequate dispersion during inhalation. The respirable fraction, expressed as fine particle dose (particles below 5 µm), remained above 25% of the nominal dose, confirming the generation of particles capable of reaching the lower respiratory tract. Aerodynamic deposition profiles indicated a clear influence of airflow rate on powder dispersion, with higher airflow promoting enhanced deagglomeration and increased deposition in NGI stages associated with respirable particle sizes.

Overall, the results demonstrate that ciprofloxacin–lactose binary systems exhibit suitable emission and aerodynamic characteristics when delivered using a capsule-based dry powder inhaler. The observed relationship between airflow conditions and respirable fraction highlights the importance of both formulation design and inhalation parameters in achieving efficient pulmonary drug delivery. These findings support the further development of ciprofloxacin dry powder inhalation formulations for targeted treatment of respiratory infections.

Funding: This research is funded by a research grant from the Medical Research Agency (ABM), Poland, under the National Recovery and Resilience Plan, project number KPOD.07.07-IW.07-0216/24.

Keywords: ciprofloxacin, lactose, dry powder inhaler, APSD, NGI

References:

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Biography:

Kinga Lewandowska is a pharmacist and a PhD candidate at the Doctoral School of the Collegium Medicum, Nicolaus Copernicus University in Toruń, Poland. Her research focuses on the development and physicochemical characterization of dry powder inhalation formulations, with particular emphasis on antibiotic delivery systems for pulmonary administration. Her work involves formulation design, aerodynamic performance assessment using cascade impactors, and advanced analytical techniques such as UPLC for quantitative evaluation of inhaled drug products. She is actively involved in research projects related to innovative drug delivery technologies, including hot-melt extrusion and capsule-based inhalation systems. Her scientific interests include pulmonary drug delivery, pharmaceutical technology, and translational development of inhaled medicines for respiratory diseases.