This new FIA product addresses the dynamics of testing dry-powder inhalers (DPIs). Compendial methods of testing DPIs call for an abrupt start and abrupt end to the air flow. An attribute aimed at representing the way a patient uses a DPI. The starting and stopping of the air flow introduces time-variant conditions in the test equipment (cascade impactor) and in the device itself. Experimental and computational studies of these conditions are continuing to elucidate the important characteristics of the device and test system that should be known and controlled to establish a sound quality control test for products that are or are about to be registered. FIA’s latest instrument known as Stig puts in users hands the most important measure of the time-dependent air flow start-up the rise-time. It is important that the rise-time is known and under control when testing inhalable devices. Russell-Graham and colleagues1showed that the fine particle dose increases as the rise time decreases. Previous and subsequent theoretical analyses point out reasons for this effect.2, 3 For established products quality control (QC) testing requires knowing that the rise-time remains in a specified range…now possible with Stig. For GMP QC Stig can be locked to acquire and present the rise-time according to a defined and validated method. Since patients do generate different inhalation air-flow profiles it is also important during the development of a new drug product to adjust the prototype devices to exhibit a sensible rise-time close to what will take place in patient use. This mindset is equally important for DPIs and for breath-actuated MDI devices. Stig also makes possible the recording of air-flow profiles so that they can be reproduced on a breathing simulator (such as F-SIG 6300) for studying nebulizers. Versatile and user-friendly. Best-in-class – that is the new Stig from FIA.

Key features of Stig:

  • Rise-time measurement 0.1-1 s using a thermal flow meter
  • Average rise-time from a series of measurements
  • Touch-screen which displays a graph of flow vs. time, rise-time and the final flow
  • Printed records of the measurement with optional printer. Has been validated together with Mettler-Toledo printers, customer can use own printers (e.g. from lab balances)
  • Rise-time profile saved to USB-memory
  • Date and time
  • Battery powered
  • Optional IQ/OQ and quality certificate for the regulated industry

Download the pdf Rise-time Measurement Instrument Stig

  1. Russell-Graham, D., A. Cooper, B. Stobbs, E. McAulay, H. Bogard, V. Heith, E. Monsallier, “Further Evaluation of the Fast-Screening Impactor for Determining Fine-Particle Fraction of Dry Powder Inhalers, “Drug Delivery to the Lung, December 8 to 10, 2010, Edinburgh, Scotland.
  2. Roberts, D. L., M. Chiruta, “Transient Impactor Behavior during the Testing of Dry-Powder Inhalers via Compendial Methods, “Drug Delivery to the Lung 18, The Aerosol Society, Edinburgh, Scotland, December 13-14, 2007.
  3. Versteeg, H., P. Zhao, C. Blatchford, M. Copley, D. L. Roberts, J. P. Mitchell, “A Computational Fluid Dynamics (CFD) Model of the Start-Up Kinetics of the Andersen Cascade Impactor (ACI), “Drug Delivery to the Lung, Aerosol Society, Edinburgh, Scotland, December 9-11 2015; pages 18-21.