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Pharmaceutical Aerosol Research at Carleton University

Edgar Matida

Associate Professor, Department of Mechanical and Aerospace Engineering, Carleton University

October 10, 2013 15:00 - 16:00

River Building, room 3228, Carleton University

 

abstract

Pressurized metered dose inhalers (pMDIs or "puffers") and other devices, such as nebulizers and dry powder inhalers (DPIs), are widely used in the treatment of asthma and bronchitis. Statistics by the Canadian Lung Association show that approximately 7-10% of the population will require treatment for certain respiratory illnesses in some part of their lives. Although the lung is the final target of the aerosol medication, a significant portion of the dose, 67-81%, will be lost mainly through aerosol deposition on the walls of the mouth-throat-trachea region (and also inside the device itself), meaning a departure from ideal delivery to the lungs with considerable side effects (nausea, cramps, etc.). All the three types of devices have some shortcomings: 1) PMDIs require actuation-inhalation synchronized coordination. 2) Nebulizers use a small compressor during operation and have portability issues. 3) Although DPIs depend only on the inhalation effort of the patient, DPIs will normally have very complex and relatively small outlet flows, which will increase aerosol deposition in the mouth. When attached to pMDIs add-on devices (spacers) can enhance the performance of the inhaler by optimizing flow conditions (lower velocities and turbulence kinetic energy) to reduce deposition (mainly in the mouth) and increase the amount of drug delivered into the lungs for the same dosage. The shape of the add-on devices available on the market are relatively simple (cylindrical shapes), and apparently no detailed shape optimization has been reported in the literature. Recent investigations (in our group) indicate that the spray angle from pMDIs deflects downwards (up to six degrees) and then upwards (back to zero degrees) during the duration of an actuation (100 ms), causing more aerosol deposition in the lower-half region of spacers. We have been undertaking comprehensive studies of pMDIs and add-on spacers, which cannot be found in the literature. In addition to the traditional treatment of lung diseases, nasal drug delivery using pharmaceutical aerosols is emerging as an important alternative for treating many conditions such as diabetes (insulin delivery), osteoporosis, and even migraine headaches. The nasal tract can be used in vaccinations as well. This type of delivery has clear advantages, namely, needle-free, patient-friendly, and fast and high levels of medication adsorption. Due to complexity of the nasal cavity and differences in regional medication absorptiveness, which is also affected by the medication properties (formulation and aerosol characteristics, i.e., density, shape and size of individual particles) and fluid flow structures, the ideal nasal drug delivery remains a challenging problem. In collaboration with the Ottawa Civic Hospital, we have been developing a novel and idealized nasal cavity geometry, which is a potential candidate to be used as a standard (for aerosol deposition measurements) in the pharmaceutical field. Although requiring some further developments (for example: inclusion of nasal hair), an initial standardized geometry based on 30 patients was recently created by our group.

biography

Edgar Matida is an Associate Professor in the Department of Mechanical and Aerospace Engineering at Carleton University. His research focuses on the enhancement of both lung and nasal drug delivery systems by comprehensive studies of aerosol generation, transport, and deposition in idealized replicas, which could be adopted as standards in the pharmaceutical field. In order to better understand the physics of the delivery systems, he has been combining experimental analysis (aerosol characterization, aerosol deposition, and fluid flow field measurements) with CFD (Computational Fluid Dynamics) numerical simulations.