In respiratory drug development various factors can affect the spray pattern and plume geometry: the size and shape of the actuator orifice, the design of the actuator, the size of the metering chamber, the size of the stem orifice of the valve, the vapor pressure in the container, and the nature of the formulation. Understanding these effects becomes essential to successful drug development and approval.

The ideal way to conduct testing of orally inhaled and nasal drug products (OINDPs) is automated, mechanical actuation using a defined testing profile derived from human-usage data. This approach reduces variability and is in line with patient usage. It also makes it possible to avoid the inherent human error that arises due to operator fatigue and other influences when testing a high volume of samples.