Spacer or actuator for inertial removal of the non-respirable fraction of medicinal aerosols

#The present invention relates to a spacer or actuator for inertial removal of the non-respirable fraction of medicinal aerosols. The present invention also relates to medicinal aerosol inhalers employing a spacer or actuator for inertial removal of the non-respirable fraction of the medicinal aerosol.

#Medicinal aerosol inhalers are commonly used to treat a number of medical conditions. It is well known that medicinal aerosols, whether they originate from a metered dose inhaler (MDI), dry powder inhaler (DPI), or a nebulizer, consist of a distribution of particles with varying sizes. For a particle to be considered respirable, meaning it will have a high probability of depositing in the lung upon inhalation, it should have an aerodynamic diameter of less than about 4.7 micrometers. Larger, non-respirable particles can be deposited in a patient's mouth and/or throat, which can lead to undesirable effects. Mouth and/or throat deposition can lead to a displeasing taste, as well as potentially causing side effects related to drug dosing by a non-inhalation route. It is thus desirable to provide an aerosol dose to a patient that consists primarily or entirely of respirable particles, that is, a dose that has a high respirable fraction.

#In the development and manufacture of medicinal aerosol formulations, however, there are many factors that need to be taken into consideration, for example, drug solubility and/or stability in a suitable medium, the ability to prepare small particles, and the necessary dosage. Oftentimes, it is not possible or practical to make a medicinal aerosol where all of the particles delivered by a conventional device are respirable. A number of efforts have been made to develop spacers or actuators that provide either a longer or more tortuous path between the formulation reservoir and the patient to either remove non-respirable material or disperse larger aggregates into smaller particles. Medicinal inhaler spacers have incorporated additional distance and/or various configurations of baffles as a method for removal of non-respirable particles (U.S. Pat. No. 5,676,130, Gupte et al.; WO 92/04066, Bisgaard). Rotational motion of an airflow stream has also been proposed (U.S. Pat. No. 6,073,629, Hardy et al.) and in particular airflows described as cyclonic wherein the airflow travels from inlet to outlet by spiraling in one direction along a central axis (U.S. Pat. No. 5,476,093,Lankinen; WO 01/00262, Hamer et al.).

#Preferred embodiments of the invention will now be described in greater detail below with reference to the attached drawings, wherein:

#FIG. 1 is a perspective view of a medicinal inhaler spacer.

#FIG. 2 is a perspective view of a medicinal inhaler spacer.

#FIG. 1 shows a perspective view of a preferred embodiment of a medicinal inhaler spacer 100 of the present invention.

#The spacer 100 comprises an inlet 110 that is located tangentially on a circumferential outer surface of a chamber 130. The inlet 110 adjoins the chamber 130 along the proximal end 132 of the chamber. As shown in FIG. 1 the inlet 110 is cylindrical, but it may also be rectangular, oval, tubular, or any like shape that will provide for an opening into the chamber 130 through which air may flow.

#The chamber 130 preferably has rounded sides and the proximal end 132 of the chamber is more preferably in the shape of a cylinder that defines a central axis 150. The chamber 130 has a taper over its distal end 134, preferably in the form of a distally converging cylinder. As shown in FIG. 1 this distally converging cylinder may be closed at its distal end. Alternatively, as shown in FIG. 2, the distal end 234 of the chamber 230 tapers towards a point making the distal end of the chamber conical, as opposed to the truncated conical distal end shown in FIG. 1.