The present invention relates to a device for feeding, de-agglomeration and electrostatic charging of a pulverized powder for inhalation by means of stationary or portable devices, whereby powder refers to active pharmaceutical substances and mixtures and specially treated preparations intended to be administered via the respiratory tract.
Administering of medical powders today is performed in numerous ways. Within health care more and more is focussed on the possibility of dosing powder directly to the lungs by means of an inhaler to obtain an effective, quick and patient-friendly administering.
For the medical powders, being administered by means of an inhaler, to land in the lungs, the powder should have a grain size of 1 to 6 xcexcm. A larger grain size will stick in the mouth and throat and a smaller grain size accompanies the expiration.
Powder having a small grain size will have a strong tendency of agglomerating, i.e. to get conglomerated. In the inhalers which are used today a large extent of the active substance is in the form of agglomerates when it is dosed and much powder therefore will stick in the upper respiratory tract. Different ways to de-agglomerate the powder have been developed and in most cases the inhalation air is utilized for decomposing the agglomerates.
It is also common to use carriers having a larger grain size onto which the fine powder is distributed. Upon inspiration the large grains will then stick in the oral cavity while the small grains are set free and proceed to the lungs. Certain manufacturers also use electrically driven propellers, piezo-vibrators and/or mechanical vibration to decompose the agglomerates. Thus, achieving a very large portion of individual particles in the inspiratory air is a very important factor for obtaining a high degree of effectiveness upon inhalation.
In the Swedish patent publication SE 504 458 a device for an inhaler is disclosed, which utilizes a rotating drum as dosing device together with an electric field, which document hereby is incorporated by reference.
The present invention relates to a device for feeding, de-agglomeration and electrostatic charging of a fine powder, especially intended for inhalation purposes. The electrostatic charging takes place by means of tribo-, corona-and/or induction-charging. Charging of the powder is from now on referring to an electrostatic charging according to any of the mentioned ways or a combination of those. Particularly the device according to the present invention is used for dosing powder directly to the inspiratory air, alternatively providing a dosing device with electrostatically charged de-agglomerated powder for a more controlled dosing to the inspiratory air, alternatively application to a carrier for further preparation and introduction to an inhaler or other device, e.g., a piece of plaster or the like.
The de-agglomeration takes place in that two rotating brushes containing powder are touching each other. The bristles of the brushes are pinched and scraped toward each other and thereby decomposing the powder agglomerates. At the same time also an electrostatic charging of the powder may take place. The rotation speed of the brushes is optimized to achieve optimal results for different powder substances. The design of the brushes is preferably optimized for the substances to be de-agglomerated and electrostatically charged.
The choice of material then is adapted to the function the brushes are intended to have. If anti-static brushes are used, the main function is to decompose the agglomerates, while if another material is used, as for instance nylon, also a more pronounced electrostatic charging of the powder takes place.
As it is in practice impossible to obtain a complete de-agglomeration within the brushes, the dust delivered from the flipping device will contain a small amount of agglomerates. To have these agglomerates not to be integral in the powder to be dosed a separation must take place. This is arranged in a classification device, where a flipping takes place in the direction towards a reception device and where an electric field is present perpendicular to the direction of flipping. The kinetic energy, which is essentially larger for the agglomerates, will then convey the large particles to the reception device, while the small individual particles will be attracted to a dosing drum by means of the electric field. In this way only the individual particles will in practice be utilized for dosing.
The invention is defined by the independent claims 1 and 5 and different embodiments are defined by the dependent claims 2-4 and 6-14, respectively.