Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
1998-03-17
2001-04-03
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
C128S203120, C128S203210, C128S200240, C604S058000
Reexamination Certificate
active
06209538
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved medicament inhalator. More particularly, the present invention relates to a dry powder medicament inhalator usable by asthmatics and the like in such a manner to facilitate proper deposition of the medicament in the lungs. By inhaling on a mouthpiece, a prescribed dosage of medicament becomes available to the patient during the proper phase of inspiration to maximize deposition of the medicament in the lungs of the user.
STATE OF THE ART
The widespread existence of asthma and other respiratory disorders which inhibit proper breathing has lead to the development of numerous medications which can be used to open restricted breathing passages and to enable the user to breathe more freely. Some asthmatics suffer from only occasional attacks. Other asthmatics suffer from attacks which are relatively minor and do not cause a serious inconvenience. For others, however, breathing is a constant struggle which would be nearly impossible without the appropriate medication. These medications may be in either dry or liquid form, depending on the type of medication.
There are essentially two types of inhalation devices currently available in the marketplace for the administration of a medicament to the lungs. The predominant inhalation device is a pressurized, metered dose inhaler containing a suspension of drug in a pharmaceutically inert liquid propellant, e.g., chlorofluorocarbons or fluorocarbons. Inhalation devices of this type are well known in the art and are commonly used.
These propellant-based inhalation devices have the advantage of consistently delivering a predetermined dose of medication form the aerosol canister. However, the drug particles are propelled at high velocity from the inhalation device. A significant quantity of the medication impacts tissue in the mouth or throat of the patient, becoming unavailable for deposition in the lungs. Further, growing concern over the link between depletion of atmospheric ozone and chlorofluorocarbon propellants has focused attention on the development of alternative means of delivering medication to the lungs, including the development of dry powder inhalation systems.
Dry powder inhalers represent the second major type of inhalation devices. Dry powder inhaler devices known to the applicants and existing in the marketplace utilize the patient's inhaled breath as a vehicle to transport the dry powder drug to the lungs. Presently there are four principal methods in use to provide fine particulate powder to the lungs without the use of chlorofluorocarbons or other propellants.
The first method available relies on the use of a hard gelatin capsule which contains a premeasured dose of therapeutically active material and an inhalator device for use with the capsule. The capsule is placed in the inhalator device which serves to open or perforate the capsule, exposing the dose of medicament. The medicament is removed from the capsule by the vacuum action created when the patient inhales through the mouthpiece of the device, and is entrained in the inspired air stream for transport to the patient's lungs. The empty capsule is removed from the inhalation device after each use.
Inhalators using this type of capsule technology are described in U.S. Pat. No. 3,807,400 (Cocozza); U.S. Pat. No. 3,906,950 (Cocozza); U.S. Pat. No. 3,991,761 (Cocozza) and U.S. Pat. No. 4,013,075 (Cocozza). The intent in each of these devices is to remove all of the powdered medicament from the interior of the capsule. However, it has been found that the air stream generated by the patient is typically insufficient to accomplish complete removal of medicament from the capsule. This may be especially true for a patient having reduced inhalation ability due to an asthma attack. Further, gelatin capsules are affected by relative humidity during storage and may become hydrated in moist environments. Hydration results in poor opening of the capsule and agglomeration of the powder contents, or dehydrated, resulting in brittle fracture of the capsule, potentially making fine gelatin fragments available for inhalation or compromising dosing due to electrostatic attraction of medicament to the capsule surfaces.
A second method for delivery of dry powder medicaments relies on providing a package containing multiple doses of medicament, each contained in a sealed blister. The package is used in conjunction with a specially designed inhalation device which provides a means of attachment for the package and perforation of an individual blister by the patient prior to the inhalation of its contents. Delivery systems of this type are described in EPO Patent Application Publication No. 0 211 595 A2 (Newell et al.); EPO Patent Application Publication No. 0 455 463 A1 (Velasquez et al.); and EPO Patent Application Publication No. 0 467 172 A1 (Cocozza et al.). As the patient inhales, a portion of the inhaled air stream flows continuously through the perforated blister entraining the medicament and providing for inclusion of the medicament in the inspired breath. Delivery of medicament to the patient's inspired air stream begins as sufficient flow develops through the blister for removal of the medicament. No means is provided by which the point or rate of delivery of medicament to the patient is controlled.
A third method for delivery of dry powder medicaments involves the use of a device equipped with a drug reservoir containing sufficient medicament for a much larger number of doses. The Draco TURBUHALER® is an example of this type of device and is described in detail in U.S. Pat. No. 4,688,218 (Virtanen); U.S. Pat. No. 4,667,668 (Wetterlin); and U.S. Pat. No. 4,805,811 (Wetterlin). The device provides a means for withdrawing a dose of medicament from the reservoir and presenting the withdrawn dose for inhalation by the patient. As the patient inhales through the mouthpiece of the device, the medicament contained in perforations in a dosing plate is entrained in the inspired air and flows through a conduit or conduits. The conduits serve as a vortex creating a means for breaking up powder agglomerates before the medicament becomes available to the patient. Moisture ingress in the reservoir results in agglomeration of the powder contents, compromising dosing due to retention of powder in the perforations in the dosing plate and potentially inadequate breakup of particulates in the inspired air stream.
A fourth method for delivery of dry powder medicaments involves the use of a piston to provide air for either entraining powdered medicament, lifting medicament from a carrier screen by passing air through the screen, or mixing air with powder medicament in a mixing chamber with subsequent introduction of the powder to the patient through the mouthpiece of the device. Devices of this general type are described in PCT WO 93/12831 (Zirerenberg et al.); German Patent No. DE 4133274 A1 (Kuhnel et al.); German Patent No. DE 4020571 A1 (Hochrainer et al.); and U.S. Pat. No. 5,388,572 (Mulhauser et al.). The incorporation of a piston system, in each case, adds to the complexity of the inhalation device, both in terms of use by the patient and device manufacturability.
Thus, there is a need for an improved medicament inhalator wherein the availability of the medicament is controlled to ensure that the medicament is properly deposited in the lungs. Such a device preferably should be configured to release medicament into the inspired air stream during inhalation when a defined inhalation rate has been achieved. Such a device should also ensure that medicament agglomerations and medicament carried agglomerations are broken up before reaching the patient to ensure delivery of a consistent dose of medicament to the patient. In addition, the device should enable repeated use without redosing, or redosing in a manner which is convenient and unlikely to interfere with the use of the device when the user is undergoing an asthma attack.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a medicament
Casper Robert A.
Farrar David S.
Gardner David L.
Leith Frank A.
Lyon Zachary W.
Morriss Bateman O'Bryant & Compagni
Srivastava V.
Weiss John G.
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