Two Complementary Approaches with a Common Objective of Assuring Efficacy and Safety for Patients
By Jolyon P. Mitchell PhD, FRSC(UK), C.Chem, C.Sci, Jolyon Mitchell Inhaler Consulting Services Inc., London, Ontario, Canada
WHAT ARE CONSIDERED ORALLY INHALED PRODUCTS (OIPs)?
The term ‘orally inhaled product’ comprises the following major inhaler types (Figure 1):
· Pressurized metered dose inhalers (pMDIs) and associated add-on devices (spacer or valved holding chamber (S/VHC)), used to improve deposition efficacy to the airways of the lungs.
· Dry powder inhalers (DPIs) that are commonly passive in that the patient provided the energy by inhalation to disperses and transport the dry aerosol containing medication, but active DPIs that are becoming more prominent, contain electromechanical means to initiate and control aerosol generation and transport to the patient.
· Soft mist inhalers (SMIs) that create a low velocity droplet stream without using a propellant by a variety of means including forcing two jets under spring-applied pressure to pump the medication is aqueous form from its reservoir to collide at the exit, thereby greatly reducing droplet momentum.
· Nebulizers that comprise a large group of devices using various means for aerosol generation including: (a) compressed air delivering droplets containing aqueous medications in suspension or solution from a narrow orifice by the Venturi effect (jet nebulizers), (b) electro-mechanical action applied to liquid stream passing through a micro-orifice containing mesh/membrane, (c) ultrasonic energy applied to the bulk liquid in a reservoir (solutions only) or (d) more sophisticated devices using electronics to control droplet size and timing of delivery of a bolus during inhalation.