Measuring the ‘cold freon’ effect

Copley Scientific’s new PTT 1000 takes the temperature of inhaled aerosols

Plume Temperature Tester PTT 1000

Copley Scientific’s Plume Temperature Tester (PTT) 1000 is a high precision instrument for measuring the plume temperature of Metered-Dose Inhalers (MDIs) and nasal sprays.

The Nottingham-based firm says this is the first instrument on the market to measure reliably plume temperature during dose delivery, supporting determination of the ‘cold freon’ (chilling sensation) that inhaler users often experience. Because this effect can have a direct impact on the consistency and efficiency of drug delivery, Copley Scientific says the PTT 1000 is particularly useful for those seeking to demonstrate therapeutic equivalence or develop softer, warmer plumes with improved patient compliance rates.

The widely recognised cold freon effect is due to the high velocity blast and subsequent evaporation of liquid propellant that hits the back of the throat during drug delivery. Since the effect is a function of both aerosol spray force and plume temperature, Copley Scientific offers the PTT 1000 alongside the Spray Force Tester 1000, an instrument that measures the impaction force of delivery. Together they provide a combined solution for complete quantification.

In certain instances the cold freon effect can result in the patient aborting the inhalation process and is therefore a significant cause of inconsistent drug delivery. This effect is specifically given as an example of a criterion that might be required to substantiate in vitro therapeutic equivalence in EMA guidelines for orally inhaled products (OIP) (January 2009). With an internal geometry identical to that of the standard USP induction port used for all orally inhaled product testing, the PTT 1000 incorporates a series of four thermocouples that measure a precise temperature profile of the plume at different distances from the actuator.

A data acquisition system under the control of an associated PC ensures efficient data capture and display, and the thermocouples are easily removed for cleaning. The new tester can be directly connected to a Waste Shot collector or Dose Uniformity Sampling Apparatus for streamlined integration within existing test set-ups.

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Copley Scientific Ltd (more information, website)