Deposition Dosages of Three Cromolyn Forms by Cascade Impactor

Among inhaled asthma therapies, the present study aimed to identify factors for selecting the type of inhalation therapy for asthma. Three methods are used to deliver inhaled cromoglycate, and the airway deposition rate was evaluated using a cascade impactor with 3 dosage forms: dry powder (DP), pressurized metered dose inhaler (pMDI), and solution (jet- and mesh-types). The percentage of particles with diameters of 2-6 μm was 17.0% for the capsule, 51.8% for pMDI, 49.0% for jet-type NE-C28, and 40.4% for mesh-type NE-U22. The amounts of drug deposited in the bronchi were based on the particle distribution of the various dosage forms: 3.4 mg for the capsule, 1.0 mg for pMDI, 9.8 mg for one solution (jet-type NE-C28), and 8.1 mg for the other solution (mesh-type NE-U22). Jet-type or mesh-type electric nebulizers delivered 2-3 times more of the drug than capsules, and, compared with pMDI, 8-9 times more of the drug was deposited in the bronchi/bronchioles. Electric nebulizers are considered the best method. This study suggests that the size of particles deposited at sites of obstruction is larger than previously reported, and no obstruction of small airways occurs (<2 mm).