Aerosol deposition in the human lung following administration from a microprocessor controlled pressurised metered dose inhaler.

Abstract

Background -Gamma scintigraphy was employed to assess the deposition of aerosols emitted from a pressurised metered dose inhaler (MDI) contained in a microprocessor controlled device (SmartMist), a system which analyses an inspiratory flow profile and automatically actuates the MDI when predefined conditions of flow rate and cumulative inspired volume coincide. Methods -Micronised salbutamol particles contained in a commercial MDI (Ventolin) were labelled with 99m-technetium using a method validated by the determination of (1) aerosol size characteristics ofthe drug and radiotracer following actuation into an eight stage cascade impactor and (2) shot potencies ofthese non-volatile components as a function of actuation number. Using nine healthy volunteers in a randomised factorial interaction design the effect of inspiratory flow rate (slow, 30 1min; medium, 90 Vmin; fast, 270 /min) combined with cumulative inspired volume (early, 300 ml; late, 3000 ml) was determined on total and regional aerosol lung deposition using the technique of gamma scintigraphy. Results -The SmartMist firing at the mediumlearly setting (medium flow and early in the cumulative inspired volume) resulted in the highest lung deposition at 18-6 (1.42)%. The slow/early setting gave the second highest deposition at 14a1 (2.06)% with the fastllate setting resulting in the lowest (7.6 (1-15)%). Peripheral lung deposition obtained for the mediumlearly (9.1 (0.9)%) and slowlearly (7.5 (1.06)%) settings were equivalent but higher than those obtained with the other treatments. This reflected the lower total lung deposition at these other settings as no difference in regional deposition, expressed as a volume corrected central zone:peripheral zone ratio, was apparent for all modes of inhalation studied. Conclusions -The SmartMist device allowed reproducible actuation of an MDI at a preprogrammed point during inspiration. The extent ofaerosol deposition in the lung is affected by a change in firing point and is promoted by an inhaled flow rate of up to 90 1/min -that is, the slow and medium setting used in these studies. (Thorax 1995;50:639-644)

Washing plastic spacers in household detergent reduces electrostatic charge and greatly improves delivery

“…The in vivo study demonstrates that electrostatic charge plays an important role in the lung deposition of salbutamol through plastic spacers, and that the effect of reducing charge is much greater than expected. Using detergent-coated Volumatic spacers, a mean lung deposition of salbutamol of 45.6% was found, which was much higher than in previous studies [11±14, 18,19].…”

“…Most deposition studies using radiolabelled salbutamol have examined the use of pMDIs, dry powder inhalers, or nebulizers, and have reported mean lung deposition percentages between 9 and 21.6% [11,18,19]. There are few deposition studies involving the use of a spacer device, and the results of these studies are highly variable.…”

Intensive Therapy With Inhaled Insulin via the AERx Insulin Diabetes Management System

“…This alternative is mainly recommended and used in patients with type 1 diabetes. One recent development is that of inhaled insulin systems, and current published data have shown the clinical viability of inhaled insulin in all patients with diabetes (8,9).The AERx insulin diabetes management system (iDMS) addresses factors such as particle size (10) and breathing technique (11,12), which have to be correctly controlled if inhaled insulin is to be clinically feasible. AERx iDMS delivers, from a unique insulin strip, liquid insulin aerosol droplets (1-3 m) to the deep lung, only during precise predefined inspiratory flow and volume (12).…”

“…The AERx insulin diabetes management system (iDMS) addresses factors such as particle size (10) and breathing technique (11,12), which have to be correctly controlled if inhaled insulin is to be clinically feasible. AERx iDMS delivers, from a unique insulin strip, liquid insulin aerosol droplets (1-3 m) to the deep lung, only during precise predefined inspiratory flow and volume (12).…”

Avanços na inaloterapia em pediatria

“…54 SmartMist ® (Figure 6), produced by Aradigm Corporation, USA, has a microprocessor that records the patient's inhalation pattern and only actuates the device when a predefined combination of inspired volume and flow rate is achieved. 56 Advances in inhalation therapy in pediatrics -Muchão FP & da Silva Filho LV Velocity-modifying metered-dose inhalers reduce aerosol velocity when it is released from the device, reducing drug deposition in the oropharynx. The Spacehaler ® (Evans Medical, UK), for example, is compact and has an actuator orifice capable of producing a swirl of particles in the aerosol, reducing its velocity.…”