Introduction to Critical (Sonic) Flow Control

The vast majority of Dry Powder Inhalers (DPIs) are classified as “passive” breath activated devices, that is to say, they rely solely on the patient’s inspiration to operate.

There is no necessity to co-ordinate breathing with the activation – the patient simply inhales deeply to access the drug.

It follows that both the delivered dose and fine particle dose of DPIs are dependent on the strength and duration of the patient’s inspiration, a critical quality attribute (CQA) which must be simulated during in vitro testing.

The testing of DPIs is further complicated by the fact that different inhalers provide varying degrees of resistance to flow i.e. some require more effort to inhale than others.

The Critical Flow Controller Series TPK allows the setting of specific flow rates and simulated inspiration volumes whilst at the same time maintaining the critical (sonic) flow conditions and hence stable flow control critical to good measurement practice.

Two versions are available, the TPK and TPK 2000.

For comprehensive product details, specifications and part numbers, please request a copy of our brochure “Quality Solutions for Inhaler Testing”.