Lung deposition patterns of directly labelled salbutamol in normal subjects and in patients with reversible airflow obstruction.

Abstract

Deposition was assessed by a dual headed gamma camera after inhalation of the drug. Results-The total mean (SD) percentage deposition of the drug in the normal subjects was 21-6% (8.9%) with the MDI alone, 20-9% (7-8%) with the AMDI with spacer, and 12-4% (3-5%) with the DPI. For the patients, the mean percentage deposition was 18-2% (7.8%) with the MDI alone, 19-0% (8-9%) with the MADI and spacer, and 11-4% (5-0%) with the DPI. Bronchodilatation achieved by the patients was similar with all three techniques. Mean peripheral lung deposition was significantly greater with a spacer device than when the MDI was used alone in both normal subjects (49.4% (6-1%) v 44-1% (9.9%)) and patients (38-6% (11.1%) v 30-4% (9.4%)).

Lung deposition from the Turbuhaler in children with cystic fibrosis

“…Scintigraphic and pharmacokinetic deposition studies have indicated that this device is capable of delivering a mean of 20-30% of the nominal dose to the lungs of adults [1,2]. Although it is difficult to compare results from studies utilizing different methods [3], these results suggest that the device delivers a greater proportion of the nominal dose to the lungs of adult patients than do other DPIs [4,5], metereddose inhalers (MDIs) [4,6,7], and jet nebulizers [8,9], and these results are similar to optimal values obtained using certain MDI-spacer combinations [6].In vitro deposition studies have indicated that the performance of the Turbuhaler®, and other DPIs, can be significantly influenced by the peak inspiratory flow (PIF) achieved through the device [2,5,[10][11][12][13][14][15][16]. The fine particle dose delivered by a Turbuhaler®, measured in vitro using multistage liquid impingers, decreases with decreasing flow [16].…”

“…Scintigraphic and pharmacokinetic deposition studies have indicated that this device is capable of delivering a mean of 20-30% of the nominal dose to the lungs of adults [1,2]. Although it is difficult to compare results from studies utilizing different methods [3], these results suggest that the device delivers a greater proportion of the nominal dose to the lungs of adult patients than do other DPIs [4,5], metereddose inhalers (MDIs) [4,6,7], and jet nebulizers [8,9], and these results are similar to optimal values obtained using certain MDI-spacer combinations [6].…”

“…Since we did not directly quantify the dose exhaled, this will slightly overestimate the lung dose, but previous studies have indicated that the exhaled dose using high inspiratory flows with DPIs is less than 1% of the nominal dose. Hence, the dose on the inspiratory filter will be very close to the delivered dose [1,2,4,5].…”

Airway deposition and airway effects of antiasthma drugs delivered from metered-dose inhalers

“…No difference was observed in total lung deposition when a group of patients and healthy volunteers were compared using salbutamol pMDI, although the deposition patterns were more central in the patients [20]. A breath-actuated pMDI, which triggers the inhaler at a specific inhalation flow, and thus avoids the need to co-ordinate inhalation and actuation, has been tested in patients considered to be "good" and "bad "co-ordinators [63].…”

“…regional deposition data; the most usual divisions of the lungs are into central, intermediate and peripheral zones, representing mainly large, medium and small airways, respectively [19], or into a central one-third and a peripheral two-thirds of the lung fields [20]. The lung edges are usually defined either by ventilation scans using a radioactive inert gas [21], or by a transmission scan using a large flood field source [18].…”