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Where appropriate, design verification through
aerosol testing is
achieved by utilizing a variety of procedures recognized in various standards
and guidelines. In addition, our aerosol laboratory staff are actively involved
in the scientific community to better develop in-vitro test methodology and
standards, publish and present papers and to improve the understanding of
aerosol science associated with inhalation therapy. The laboratory plays a
critical function to shorten time to market and provide a strong
indication of likely device performance in a clinical setting.
We utilize a variety of techniques and the
following provides an overview of the function and environment in
which the laboratory operates.
- The laboratory functions in a GLP environment.
We primarily use compendial in vitro test methods, but also develop our own
strategies for testing that cater to the particular applications for which
our products are designed. Our measurements are intended to provide guidance
and information to health care providers on the quantity and quality of
aerosol delivery from devices.
- The laboratory has controlled temperature
(21±2°C) and relative humidity (40 ± 10% RH), enabling consistent
measurements to be made from season to season.
- Our purpose is to define product
pharmaceutical performance in terms of the following parameters:
- particle aerodynamic size
- emitted dose
- fine particle dose
- fine particle fraction
Note - fine particles are typically < 5 µm
aerodynamic diameter which enables them to have a high probability of
penetrating beyond the upper respiratory tract to deliver therapy to the
lungs.
- Particle size is measured routinely in the
pharmaceutical industry by cascade impactors. We follow compendial practices
(e.g. Chapter 601 of the US Pharmacopeia (24th Edn, 2000):
We routinely validate our measurements by
mass balance assessments. Impactor measurements are particularly important
to characterize the emitted dose from our aerosol delivery devices.
- We also measure particle size by laser
diffractometry, a particularly useful technique for liquid droplets from our
nebulizer systems.
- We also have developed different types of
breathing simulators to test the performance of our products under
conditions that simulate actual patient use. Breathing simulators are useful
at diagnosing many aspects relevant to patient use, including:
- poor timing between operation of drug
delivery device and inhalation maneuver (e.g. delay to inhale,
exhalation instead of inhalation at the appropriate time);
- valve operation that may reduce drug
delivery to patients with low inspiratory flow rates (e.g. infants);
- built-in dead volume which can reduce
aerosol delivery particularly when used by infants and small children;
and
- drug delivery rate over several
respiratory cycles (especially useful when testing nebulizers).
- We are continuously developing better ways of
performing in vitro measurements on our products, including:
- non-invasive, real-time measurement
methods, such as time-of-flight aerosol spectrometry;
- support for the development of the Next
Generation Impactor for the pharmaceutical industry; and
- proprietary testing fixtures, including a
semi-automated facility that simulates a
user-definable delay between actuation of a metered dose inhaler and
sampling by impactor.
- We support the development of improved testing
methodologies through our commitment to standards in development to test
aerosol-based drug delivery systems such as those in development at the
Canadian Standards Association.
Andersen 8-Stage Impactor
Marple-Miller Low-Flow Impactor
Mass Balance Assessments
Laser Diffractometry
Breathing Simulator
Publications
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