Inhaler testing apparatus

1 . A volume and resistance compensator device for use in inhaler testing, the volume and resistance compensator device comprising a variable volume chamber with an inlet and an outlet, at least one of the inlet and the outlet being adjustable to vary a resistance to gas flow through the variable volume chamber, wherein the variable volume chamber comprises a cylinder and a piston movable, via a shaft, within the cylinder, wherein at least one of the inlet and the outlet is configured to receive a removable choke plate to reduce a diameter of a path of the gas flow through at least one of the inlet and the outlet, and the volume and resistance compensator further comprising at least one choke plate comprising a through hole of a set diameter.

2 . The volume and resistance compensator device according to claim 1 , wherein the variable volume chamber has a maximum volume of 1000 ml.

3 . The volume and resistance compensator device according to claim 1 , wherein the shaft comprises a graduated scale.

4 . The volume and resistance compensator device according to claim 1 , further comprising a clamp for selectively fixing a position of the piston within the cylinder.

5 . The volume and resistance compensator device according to claim 1 , comprising two or more choke plates, each choke plate comprising a through hole of a set diameter.

6 . The volume and resistance compensator device according to claim 5 , wherein the set diameter of the through hole in each choke plate is one of 2 mm, 3.5 mm, 4 mm, 4.5 mm, 5.5 mm, 6 mm, 6.5 mm and 8 mm.

7 . The volume and resistance compensator device according to claim 1 , wherein a volume of the chamber can be adjusted independently of the resistance to gas flow through the chamber.

8 . An inhaler testing apparatus comprising a collector for connection to an inhaler device, a vacuum pump for generating a gas flow through the collector, a flow controller for controlling a duration of a pressure drop experienced by the collector, and the volume and resistance compensator device according to claim 1 , wherein the volume and resistance compensator device is arranged between the collector and the vacuum pump.

9 . The inhaler testing apparatus according to claim 8 , wherein the collector comprises a sampling apparatus or a cascade impactor.

10 . The inhaler testing apparatus according to claim 9 , further comprising a passive dry powder inhaler connected to the collector.

11 . A method of testing inhalers comprising:

A) simulating an inhalation event with set parameters by flowing gas through a first collector and measuring a flow resistance and rise-time;

B) simulating the inhalation event with the same set parameters by flowing gas through a second collector and a volume and resistance compensator device and measuring a flow resistance and rise time;

C) adjusting at least one of the flow resistance and a working volume of the volume and resistance compensator device until the flow resistance and rise-time measured in step B matches the flow resistance and rise-time measured in step A; and

D) testing an inhaler using the second collector and volume and resistance compensator device as adjusted in step C to acquire data to supplement or complement data acquired from a test of the same inhaler using the first collector.

12 . The method of testing inhalers according to claim 11 , wherein step A comprises a first step A1 in which the flow resistance is measured and a second step A2 in which the rise-time is measured.

13 . The method of testing inhalers according to claim 11 , wherein step B comprises a first step B1 in which the flow resistance is measured and a second step B2 in which the rise-time is measured.

14 . The method of testing inhalers according to claim 11 , wherein the method is performed using an inhaler testing apparatus comprising a collector for connection to an inhaler device, a vacuum pump for generating a gas flow through the collector, a flow controller for controlling a duration of a pressure drop experienced by the collector, and a volume and resistance compensator device comprising a variable volume chamber with an inlet and an outlet, at least one of the inlet and the outlet being adjustable to vary a resistance to the gas flow through the variable volume chamber, wherein the volume and resistance compensator device is arranged between the collector and the vacuum pump.

15 . The method of testing inhalers according to claim 14 , wherein the variable volume chamber comprises a cylinder and a piston movable, via a shaft, within the cylinder, wherein at least one of the inlet and the outlet is configured to receive a removable choke plate to reduce a diameter of a path of the gas flow through at least one of the inlet and the outlet, and the volume and resistance compensator further comprising at least one choke plate comprising a through hole of a set diameter.