REGIONAL LUNG DEPOSITION AND CLEARANCE OF TC-99M-LABELED BECLOMETHASONE-DLPC LIPOSOMES IN MILD AND SEVERE ASTHMA

Objective: To compare the distribution and clearance of inhaled beclom ethasone dipropionate (Bec)-dilauroylphosphatidylcholine (DLPC) liposo mes in patients with mild and severe asthma. Design: A Tc-99m-labeled Bec-DLPC suspension was delivered via a nebulizer (Aerotech II). Immed iately after inhalation, anterior and posterior views of the lungs and an anterior view of the oropharynx were measured by a large field gam ma camera with the patient in a supine position. To evaluate the mucoc iliary clearance of the inhaled liposomes, anterior and posterior lung scans were repeated 1, 2, 4, and 24 h after the aerosol delivery. Pat ients: Ten patients with mild asthma (FEV1 >80% of the predicted) and 10 patients with severe asthma (FEV1 <60% of the predicted) were inclu ded in an open, parallel group study. Results: Clearance is more rapid among patients with severe asthma (p<0.0001). At the 4-h measurement, a mean of 82% (SD, 5.9) of the total pulmonary dose was detected in t he lungs of patients with mild asthma while in those with severe asthm a the figure was 69% (SD, 10.9). The ratio between central and periphe ral deposition was significantly higher for patients with severe asthm a than for those having a mild form of the disease; 1.07 (SD, 0.29) an d 0.76 (SD, 0.07), respectively (p=0.008). Conclusions: Inhaled Bec-DL PC liposomes were deposited more centrally in the lower airways of pat ients with severe asthma than those having a milder form of the diseas e. The clearance of Bec-DLPC liposomes is strikingly slow in both grou ps of asthmatic patients. However, due to the more peripheral penetrat ion of inhaled liposomes in patients with mild asthma, the clearance r ate in this group was slower than in those with-severe asthma.