Abstract：Inhalation powder aerosol refers to the preparation of the solid micronized raw material drug alone or mixed with a suitable carrier, in the form of capsules
Inhalation powder aerosol refers to the preparation of the solid micronized raw material drug alone or mixed with a suitable carrier, in the form of capsules, vesicles or multi-dose depots, using a special dry powder inhalation device, and the aerosolized drug is inhaled by the patient to the lungs. In general, only particles with an aerodynamic diameter of 1 to 5 μm can enter the lungs, and particles with smaller particle sizes are at risk of being exhaled.
Since the drug particles in dry powder inhaler (DPI) formulations are very small, the physicochemical properties of the drug particles and carrier particles are the main factors determining the nebulization performance. By improving the physicochemical properties of drug particles, the atomization performance of powder aerosols can be significantly improved. At present, the new preparation technology of inhalation powder aerosol mainly includes spray drying method, spray freeze drying method, microfluidic method, template printing technology and so on.
Spray-drying method: The preparation method of dissolving (or suspending, emulsification) medicines and excipients to form liquid, spraying by spray dryer, drying with hot air, and collecting the obtained powder.
Spray freeze-drying technology: spray freeze-drying was first studied in 1991. The drug solution was sprayed into a container containing a low-temperature medium (usually liquid nitrogen) to rapidly freeze the droplets, and then freeze-dried to obtain a liquid with good fluidity. Porous spherical particles suitable for inhalation. This method has been successfully applied to produce protein particles.
Microfluidic method: Drawing on the characteristics of spray freeze-drying, a combination of microfluidic and spray drying is used to prepare inhaled particles.
Template printing technology: It is a new particle preparation method, which is suitable for the production of inhaled powder aerosols of biological macromolecules by using the replication function in particle engineering non-wet template (printing) technology.
Among them, spray granulation is widely used in pharmaceutical production. The production method is to first mix the raw and auxiliary materials with the binder, and then continue to stir to form a uniform suspension. The solid content in the suspension is 50% to 60%, and then these suspensions are passed through a high-pressure pump by a pumping device. The nozzle or spinner is fed into a special atomizer and atomized to form fine droplets, which in turn form fine particles that are approximately spherical. Spray granulation includes the concentration, drying and granulation of raw material liquid. In the production of drugs, the drug solution or suspension is often sprayed in the hot air flow in the drying chamber by atomization. Such a high temperature will cause the moisture to evaporate quickly, and then directly form spherical dry granular drugs.
At present, spray technology has changed from simple drying to remove moisture to directional particle design, that is, under the guidance of the concept of quality by design (QbD), according to material characteristics, by adding excipients to change the formulation composition and optimize spray drying process parameters, in order to achieve satisfactory The desired powder properties are targeted.
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