In the fenoterol study, the mean oropharyngeal deposition was significantly lower for the RESPIMAT compared with the MDI (37.1% vs 71.7%, respectively; p<0.01) (Table 3). However, the use of the Aerochamber with the MDI reduced the mean oropharyngeal deposition of fenoterol to 3.6%, which was significantly lower than that for the RESPIMAT or the MDI alone (p<0.01).
The mean oropharyngeal deposition of flunisolide delivered via the RESPIMAT was 26.2%, which was similar to that for the MDI with spacer (31.2%). However, modification of the RESPIMAT by the addition of a baffle significantly reduced oropharyngeal deposition of flunisolide to a mean of 7.8%, as shown in Table 4. buy asthma inhalers online
Deposition on the Dosing Apparatus
The mean percentage of the fenoterol dose deposited on the RESPIMAT mouthpiece was significantly greater than that on the MDI actuator (21.9% vs 16.7%, respectively; p<0.05), but was much less than that deposited in the Aerochamber and the MDI actuator to which it was attached (86.2%; p<0.01), as shown in Table 3.
Using the RESPIMAT with baffle, a mean 55.4% of the dose was retained on the apparatus, of which a mean 40.8% was on the baffle. By comparison, only 42.0% of the dose was deposited on the apparatus for MDI with spacer (p<0.01), of which a mean 29.1% was on the spacer (Table 4).
Lung Deposition as a Percentage of Total Body Deposition
Lung deposition was recalculated as a percentage of total body deposition (lungs plus oropharynx) to give a measure of the degree of selectivity of deposition to the target site. The RESPIMAT device showed considerable improvement in this parameter for flunisolide (mean 63%) when compared to the MDI with spacer (mean 46%). The introduction of a baffle in the RESPIMAT mouthpiece further increased this figure (mean 79%) largely due to the effect on reducing oropharyngeal deposition since the absolute percent of the dose deposited in the lungs was lower than without the baffle. In the fenoterol study, lung deposition from the RESPIMAT as a percentage of total body deposition was dramatically increased compared with the MDI (mean 51% compared to mean 13%). The figure for MDI plus spacer was 73%, but absolute lung deposition was low compared to the deposition achieved with the RESPIMAT device.