RESUMO
OBJECTIVE: To develop a method for determination of the dissolution of inhaled drugs by using indacaterol maleate, ipratropium bromide and budesonide as model drugs, and explore the law of dissolution of inhaled drugs. METHODS: Samples were prepared and the improved paddle apparatus method (USP dissolution assay-fifth method) was used for dissolution experiment. Samples were taken at a certain time, and the drug concentration was determined by HPLC. The sample dispersion method, dissolution medium and membrane were optimized, meanwhile inhaled drugs with different properties were measured and dissolution curve was modeled. RESULTS: An improved paddle apparatus method for simulating drug dissolution in respiratory tract was developed, samples were collected using the new generation impactor and the dissolution parameters were determined to be as follows: 150 mL of dissolution medium (250 mL dissolution cup), 2% Tween 80-PBS dissolution medium, 4.5 cm watch glass (4.7 cm drug-loaded membranes and 4.7 cm mesh screen), glass microfiber filters, double-layer membranes, drug-loaded membrane fixation method (level the mesh screen) and sampling time of 3 h; Weibull model was suitable for fitting the three drugs with different solubility (r2>0.999 1). CONCLUSION: The method is simple and reproducible, and can be used to determine the dissolution of inhalation drugs; the dissolution process of inhaled drugs is consistent with Weibull model.