Two new products from Copley Scientific enable testing in accordance with methods described in a new US Pharmacopoeia (USP) monograph relating to metered dose inhalers (MDIs).
The USP monograph, <1602>, which is currently in draft form, addresses the testing of MDIs with spacers and valved holding chambers (VHCs); devices that make MDIs more suitable for paediatric patients and those with poor coordination.
The recently launched BAC 2000 breath actuated controller and BRS 1100 breathing simulator, in combination, support closely controlled testing under the representative conditions for neonate, infant, child and/or adult patients outlined in the monograph.
Inexpensive and efficient, MDIs are a popular choice for the delivery of therapeutics for pulmonary conditions. However, the coordination required to synchronise operation of an MDI with inhalation inhibits their use by certain patient groups, especially paediatrics. Spacers or VHCs address this issue by introducing a chamber containing dead volume between the MDI and the inhaling patient. The MDI is fired into the spacer or VHC and the patient then inhales freely to draw the drug into the lungs.
The new monograph recognises that the breathing profile of patients has an impact on their ability to draw the therapeutic aerosol into the lungs, from the spacer or VHC. In addition it highlights the potential variability in drug delivery efficiency arising from the introduction of a time delay between actuation of the MDI and inhalation. New test conditions are outlined, designed to capture the ‘as inhaled’ characteristics of the dose, under representative conditions.
It provides near instantaneous starting and stopping of the air flow during testing
The BAC 2000 is a timer controlled two way solenoid valve. It provides near instantaneous starting and stopping of the air flow during testing and has both delay and inhaled time functions. When testing MDIs in line with the new monograph the delay feature allows sampling of the aerosol from the spacer or VHC to start a defined time after actuation of the MDI. The BAC 2000 can also be useful for controlling the duration for which nebuliser sampling is conducted and for actuating breath-actuated MDIs during testing. It can be used for both dose uniformity testing and for aerodynamic particle size measurement by cascade impaction, where appropriate.
The BRS 1100 is a simple, microprocessor controlled breathing simulator designed to generate the breathing profiles specified by USP and Ph.Eur. for dose uniformity testing of nebulisers and, in the case of the new draft USP monograph, for MDIs with spacers and VHCs.
Neonate, infant, child and adult profiles can all be precisely generated by varying tidal volume, frequency, duration and inhalation/exhalation ratio. Starting the breathing cycle at the point of inhalation or exhalation can also be controlled as required for the testing of MDIs with spacers and VHCs, when comparing fully coordinated and uncoordinated use.
