1995 OPEN FORUM Abstracts
Effect of Longterm Reservoir Use on Dose Availability with an Inhaled Corticosteroid.
J.L. Rau. Ph.D., RRT, Y. Zhu, MD. Cardiopulmonary Care Sciences, Ga State University, Atlanta, GA 30303
Introduction: We found no guidelines on length of use with reservoir chambers, which are usually recommended with inhaled corticosteroids. Purpose: This study examined the effect of simulated longerm use of reservoir devices on does availability with an orally inhaled corticosteroid from an MDI.
Methods: Beclomethasone dipropionate (Vanceril, Schering) was delivered using three clinically available reservoirs: the Monaghan Aerochamber, the Healthscan Optihaler, and the Diemolding Healthcare ACE. MDI-reservoir systems were connected to one side of a dual-chambered test lung, whose other side was powered by an MA-2 ventilator, to simulate spontaneous inspiration. Longterm use of the devices was simulated by exhausting 5 MDI canisters through the reservoirs. Tidal volume = 1500 cc's; inspiratory flows = 30 Lpm approximately for all breaths. All oneway valves were tested in the mouthpieces during simulated use and dose testing. In two separate series, one using cleaning instructions, and one with no cleaning, devices from each brand were tested. Aerosol drug availability at the mouthpiece was filtered with cotton and measured using a spectrophotometric assay.
Results: Means (SD) were:
With cleaning: (n=3) OptihalerAerochamberACE
Baseline, mcg10.6 (1.2) 14.2 (2.7)10.2 (3.2)
After 5 MDI's, mcg9.5 (0.5) 18.5 (0.9)7.7 (2.9)
Without Cleaning: (n=3)
Baseline, mcg 11.9 (5.4) 18.5 (5.4)7.6 (2.6)
After 5 MDI's, mcg 8.7 (2.0)19.9 (7.5)8.0 (3.9)
A split-plot repeated measures ANOVA revealed that the brands differed significantly from each other (p = .0017), but with no significant change over time of use (p = .2011), with cleaning. Without cleaning, brands differed from each other (p = .0019) with no difference over time of use (p = .3265). Conclusion: The Aerochamber, which adapts the entire MDI actuator into the end of the reservoir, delivered more CS than the other two brands. The Optihaler and the ACE, both of which incorporate integral actuators, tended to decline in dose delviery of CS over time of usage. All brands showed greater variation in dose delivery without cleaning.