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Manipulation of beclomethasone-hydrofluoroalkane interactions using biocompatible macromolecules
Stuart A Jones1, Gary P Martin, Marc B Brown
1Pharmaceutical Sciences Research Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom. stuart.jones@kcl.ac.uk
Journal of Pharmaceutical Sciences
|March 23, 2006
Summary
Coating beclomethasone dipropionate (BDP) microparticles with polymers like PVA and PVP stabilizes them in hydrofluoroalkane (HFA) propellants. This improves drug delivery from inhalers, enhancing aerosolization properties for respiratory treatments.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
Background:
- Pressurized metered-dose inhalers (pMDIs) require stable drug formulations for effective delivery.
- Beclomethasone dipropionate (BDP) microparticles tend to aggregate in hydrofluoroalkane (HFA) propellants, hindering inhalation therapy.
- Biocompatible polymers are explored to enhance the physical stability of microparticle suspensions in nonpolar solvents.
Purpose of the Study:
- To physically stabilize beclomethasone dipropionate (BDP) microparticles in hydrofluoroalkane (HFA) propellants.
- To enable efficient delivery of BDP to the airways using a pMDI.
- To investigate the role of macromolecular excipients in preventing microparticle aggregation.
Main Methods:
- Spray-drying of BDP microparticles coated with amphiphilic polymers (PVA, PVP).
- Assessment of physical stability using twin-stage impinger (TSI) and in-situ laser diffraction.
- Determination of excipient solubility and zeta potential in nonpolar solvents.
Main Results:
- Uncoated BDP microparticles aggregated significantly in HFA solvent (3.13 µm to 9.86 µm).
- PVA and PVP coatings dramatically reduced aggregation, yielding stable suspensions.
- Stable suspensions exhibited excellent aerosolization properties (Stage 2 deposition >40% in TSI).
Conclusions:
- Poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) coatings enhance the physical stability of BDP microparticles in HFA propellants.
- Steric and potentially charge stabilization mechanisms contribute to the observed physical stability.
- The stabilized microparticles demonstrate improved aerosolization for pMDI applications.