| The approach of drug delivery to the lungs is to use a specific device for aerosolizingthe drug particles that are subsequently delivered to the respiratory tract through inhalationfor the treatment of local and systemic diseases. The selection of the delivery device is animportant factor affecting the effectiveness of drug deposition in the lungs. Dry powderinhalers offer the advantages of propellent-free, elimination of coordination between theinhalation and actuation, low cost, and potability, and therefore increase their popularity asdevices for inhalation.The aim of this paper is to design a dry powder inhaler with optimized structurewhere turbulence can be generated and is independent of the inhalation flow by patients.The drug particles can be effectively emitted and disintegrated to produce high fraction ofrespirable particles, which therefore produce an amazing lung deposition even at low flowrate of inhalation. Experimental investigation and numerical simulation were used incombination for the analysis of designed dry powder inhaler and for the optimization ofdevice structure. The spray-dried powders were aerosolized at a variety of flow rates bySpinhalerTM, and were subsequently deposited in the lung model of Next GenerationImpactor (NGI). The deposited powders were collected and analyzed to obtain thein-vitro deposition pattern at a specific flow rate of inhalation. The results showed thatthe flow rate had a great effect on the emitted dose and drug deposition. The softwares ofFLUENT and Design Exploration were used in ANSYS Workbench to analyze the flowfield in SpinhalerTMbased on CFD and the correspond relationship of the outlet velocityand rotor speed was found. For the design of initiative drug delivery, two parameterswere crucial in the structure designe that would affect the performance of the device to a great extent. The flow field was simulated at a variety of structure parameters, and theeffect on the flow field characteristics was analyzed including velocity, turbulent kineticenergy and particle tracks. It was found that the grid can effectively reduce turbulenceintensity and guide the flow, and the increase of the length between rotor and grid canreduce the velocity of flow. Finally, in use of optimized device models with differentstructure parameters, the drug powders were aerosolized at a series of flow rate to optimizethe parameters for drug deposition in the lungs. The optimized parameters were that thelength between rotor and grid was25mm, the number of grid holes was16, and the flowrate was30L/min. The optimized dry powder inhaler device was able to generate anideal emitted dose and amazing lung deposition at low flow rate of inhalation, which cancircumvent the disadvantages of the original device and therefore have a wider applicationfor the pulmonary drug delivery. |
