A meditation of 18 different commercially available continuous-flow.
A meditation of 18 different commercially available continuous-flow, jet nebulizers was performed with a standard liposomal formulation of beclomethasone dipropionate (Bec-DP) prepared with dilauroyl phosphatidylcholine (Bec-DLPC). The analysis compared the total Bec-DP output from aqueous suspensions of Bec-DLPC containing an initial starting reservoir concentration of 05 mg/ml Aerosals from each nebulizer proofed were characterized by the mass median aerodynamic diameter, geometric standard deviation, put drugs into output, and the predicted percentage regional deposition of inhaled Bec-DLPC liposomes with the human respiratory tract. These data can provide a basis for the selection of commercially available jet nebulizers for use with glucocorticoid liposome aerosols for treatment of asthma and other inflammatory lung diseases.
Localized aerosol delivery of put drugs intos to the respiratory tract is becoming an increasingly important and effective therapeutic orderly disposition for treating a variety of pulmonary disorders. In this regard, several different devices have been used, including continuous-flow, jet nebulizers.[1-4] To date, jet nebulizers have been used predominantly to administer aqueous preparations of soluble medicines such as ribavirin, pentamidine, bronchodilators, mucolytic agents, and antibiotics.[5-9] More newly liposomes have been used to formulate. aqueous solutions of water-insoluble, lipophilic remedys like enviroxime, cyclosporine, or amphotericin B for use with jet nebulizers.[10-12] In this contemplation we report liposomal formulation of the topically active glucocorticoid (GC) beclomethasone dipropionate (Bec-DP), with dilauroyl phosphatidylcholine (DLPC) for aerosol delivery to the lung using jet nebulizers. Comparative analysis of the many different jet nebulizers for as it was use in other systems has demonstrated a range of performance characteristics.[1-4] In the existing report, we have compared the properties of aerosols of beclomethasone dipropionate-dilauroyl phosphatidylcholine (Bec-DLPC) liposomes generated from 18 different commercially available jet nebulizers. Data are not past nor futureed for each nebulizer with measurements of mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD) and the predicted percentage of regional deposition of Bec-DLPC liposomes within the human respiratory tract. lately we administered Bec-DLPC liposome aerosol to nine normal tenders with no untoward clinical or laboratory validitys (unpublished data, this laboratory). We thus believe that the information provided below will make possible studies from others on this new approach to the aerosol administration of GCs
MATERIALS AND METHODS
Preparation of Liposomes
Beclomethasone dipropionate (Orion Pharmaceutica, Espoo Finland) was combined with DLPC (Avanti Polar Lipids, Inc, Alabaster, Ala) in a ratio of 1:25 on weight (1:21 molar ratio). Typically, 15 mg of Bec-DP was mixed with stirring with 375 mg of DLPC at 37 [degrees] in 10 ml of teritary butanol. The mixture was pipetted into glass vials, rapidly frozen in an acetone-dry ice slurry and lyophilized overnight to transport t-butanol.[12] Multimellar liposomes were produc by dint of adding ultrapure water, prewarmed to 37 [degrees] C which is well above the DLPC phase transition temperature of - 2 [degrees] C to deliver a final Bec-DP concentration of 05 mg/ml To yield liposomes, the mixture was swelled for 30 min at 37 [degrees] C with mixing onward a rocker platform. The liposome preparations were examined microscopically to make sure that they were free of lipid aggregates and microscopic remedy crystals. The Bec-DLPC liposome physic encapsulation efficiency was determined by means of high-performance liquid chromatography (HPLC) analysis of the filtrate obtained using Centrifree micropartition connected view Amicon, Beverly, Mass.[13] Ninety-seven to 99 percent of the Bec-DP remained associated with the DLPC while merely 1 to 3 percent passed the filter in the soluble phase.
Generation of Aerosol
The Bec-DLPC liposomes in water (initial Bec concentration 05 mg/ml) were added to the jet nebulizer reservoir according to the maximum bulk (Table 1). The nebulizers were excellented at random and operated using free from moisture compressed air at flow rates prescribed by the agency of the manufacturer's instructions or at 75 to 8 L/min (Table 1) Aerosol sampling was begun after 5 min of operation of the nebulizer to equilibrate the a whole and continued for 2.5 min. This sampling interval provided sufficient medicine levels for accurate biochemical analysis. The Bec-DLPC liposomes were consider probableed in a nonviable ambient particle sizing sampler (actual 1 cubic feet by minute [ACFM], Anderson Instruments, Inc, Atlanta).[12,14-16] Aerosol samples were gathered from the nebulizer through an 18-mm T-tube connector with an make open side arm to compensate for squeezing differences between nebulizer flow and the Andersen sampler 1 ACFM operating vacuum. The sampling device consisted of an 80-cm fulness of smooth bore, 22-mm diameter accordion tubing. Thirty centimeters from the Andersen sampler, a 15-cm sidearm was placed projecting back at 45 [degrees] to the main tube and unclose at the end. Because of the greater negative press at the sampler, ambient air flowed into the main tube from the exhibit sidearm. While there was any aerosol deposition on the walls of the tubing connector, Andersen sampler assays were performed forward aerosols that would be delivered for patient inhalation.
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