Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
1999-06-04
2001-12-11
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
C128S203120, C128S203230, C128S203190, C128S200250, C128S202260, C604S058000
Reexamination Certificate
active
06328033
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to drug delivery devices, and specifically to devices and methods for delivery of drugs by inhalation.
BACKGROUND OF THE INVENTION
Drug delivery by inhalation is well known in the treatment of respiratory disorders, such as asthma. Inhalation has also found use in delivery of systemic drugs through the lungs, wherein the drugs are absorbed directly into the blood stream without having to pass through (and be broken down by) the digestive tract.
Ultra-fine, dry powders, also known as micro- and nano-powders, are the subject of increasing interest in pharmaceutical manufacturing, because they provide a solution to many of the shortcomings of blended drugs. Active drug ingredients are produced, packaged and administered to the patient as pure, dry powders, without blending them with solvents or other agents. Elimination of the blending steps simplifies the manufacturing process, reduces development and manufacturing costs, makes dosage more accurate, and extends the drug's shelf life.
Dry powder inhalers are known in the art, for delivery of dry powder medications to the lungs. For optimal penetration and absorption in the lungs, the powder particles should be particularly fine—on the order of 4 &mgr;m in size, or less. The drawback of such ultra-fine, dry powders is that they are difficult to handle, tending to clump and stick in storage and to scatter when disturbed by even slight air movements. These handling problems must be overcome if dry powder drugs are to be used efficiently and safely, and special methods must be used for accurate dose processing and administration.
PCT patent publications WO 97/47346 and WO 97/47347, which are incorporated herein by reference, describe inhaler apparatus for use with fine powders. A dry powder inside the inhaler apparatus initially adheres to a substrate surface therein. When a patient using the apparatus inhales, an electrostatic field is triggered inside the inhaler. The field causes the powder to be lifted from the surface and drawn into the patient's mouth. To be handled in this manner, the powder must be pre-charged. For practical field intensities (in a hand-held device that is inserted in the patient's mouth), the amount of powder that can be delivered is limited. Furthermore, application of the field must be precisely timed relative to the patient's inhalation to avoid scattering the powder, and the air flow trigger required for this purpose is costly and complex.
MicroDose Technologies Inc., of New Jersey, offers a dry powder inhaler based on the general principles described in the above-mentioned PCT publications. In addition to the used of a timed electrostatic field, the MicroDose inhaler uses a piezoelectric vibrator, brought into contact with a blister pack containing the powder, to deaggregate the particles. The mechanical interface for transferring the vibrations to the powder in the pack is inefficient and further increases the cost and complexity of the inhaler.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improved devices and methods for delivery of dry powders to a patient by inhalation.
It is a further object of some aspects of the present invention to provide a dry powder inhaler device that deaggregates the powder without the need for a direct mechanical interface to transfer vibrations to a package containing the powder.
It is yet a further object of some aspects of the present invention to provide a dry powder inhaler device from which the powder is released during inhalation by a patient using of the device, without the need for an air flow sensor or other means of active synchronization with the patient's respiration.
It is still a further object of some aspects of the present invention to provide a multi-dose dry powder inhaler device, and Particularly such a device that allows convenient tracking of dosage and patient compliance.
In preferred embodiments of the present invention, a dry powder For delivery to a patient by inhalation is contained in a package having an opening through which the powder flows when the patient inhales. The powder is deaggregated and mobilized by application of a magnetic field. Preferably, the field interacts with the package, engendering rapid motion thereof, which deaggregates the powder.
According to an other aspect of the present invention, an electrostatic valve screen is created by means of an alternating electrostatic field in a vicinity of the opening, so as to trap particles of the powder and prevent their escape from the package except during inhalation.
In some preferred embodiments of the present invention, the alternating electrostatic field is applied using electrodes at either side of the opening. Only when air is made to flow through the opening at a rate above a given threshold, which is generally determined by the voltage applied between the electrodes, can the powder flow out through the electrostatic valve screen. The voltage is preferably set so that the flow rate passes the threshold when the patient inhales, whereby the powder is drawn out of the package and into the patient's lungs.
In some preferred embodiments of the present invention, the package comprises flexible side walls, which are made to vibrate by application of the magnetic field. The vibration of the walls deaggregates the powder in the package and generates air flow which suspends the powder in the air inside the package.
In some of these preferred embodiments, the side walls of the package are coupled to electrical wiring, preferably to coils in the form of electrical conductors applied to a surface of the walls in the manner of a flexible printed circuit. One or more permanent magnets apply a fixed magnetic field to the package. The coils on the walls of the package are driven by an alternating electrical current, generating a field that interacts with the fixed magnetic field and thus causes the walls to vibrate. Preferably, the walls comprise an array of coils, which are driven cooperatively to control the mode of vibration of the walls and thus regulate the air flow inside the package.
Preferably, the external magnetic field has a component in a direction perpendicular to a coil axis, in the plane of the coils, causing the walls to vibrate along the axis. Alternatively or additionally, the magnetic field has a component perpendicular to the plane of the coils, causing lateral vibrations.
In other preferred embodiments, the side walls of the package comprise a magnetic material, which is preferably coated on a surface of the walls. The magnetic field is applied by driving an electromagnet outside the package with an alternating current, which thus causes the walls to vibrate.
Preferably, the flexible side walls are made to vibrate at a resonant vibration frequency thereof, in order to maximize the vibrational energy. Most preferably, a frequency of the alternating current applied to the coils on the walls or to the electromagnet is set so as to engender the resonant vibration. In a preferred embodiment, the frequency of the alternating current is swept through a range of frequencies, preferably including the resonant frequency, and is then set at the Frequency that maximizes the effectiveness of deaggregation, which is typically the frequency that maximizes the wall vibration. For this purpose, a vibration sensor is preferably coupled to the wall and provides feedback for use in controlling the frequency of the alternating current. In another preferred embodiment, the vibration sensor is coupled in a positive feedback loon to a driver that provides the alternating current, causing the loop to spontaneously oscillate at or near the resonant frequency.
In still other preferred embodiments of the present invention, the powder particles comprise an electrically-or magnetically-active component, preferably in the form of a coating on or a compound in the particles. In some of these preferred embodiments, in which the particles are magnetically active, the application of
Patel Mital
Rosenman & Colin LLP
Weiss John G.
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