Surgery – Liquid medicament atomizer or sprayer – Pre-pressurized container holding medicament
Reexamination Certificate
2002-02-11
2004-05-04
Dawson, Glenn K. (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
Pre-pressurized container holding medicament
C222S635000, C128S200140
Reexamination Certificate
active
06729324
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to inhalation/breath actuated devices for use with metered dose inhalers (MDIs). Metered dose inhalers, as used herein and as commonly used in the art, are comprised of an aerosol canister which contains medicament for administration to the lungs, a metering valve which is disposed in the canister and which releases a predetermined amount of medicament from the canister when the canister is actuated, an actuator which holds the canister and includes a opening for oral inhalation, and an actuator stem which channels the medicament released by the metering valve out through the opening and toward the user. More particularly, the present invention relates to a device which receives a metered dose inhaler and which automatically actuates the metered dose inhaler responsive to inhalation by the user.
2. State of the Art
When an asthmatic or other person suffering from inhalation problems has difficulty breathing, it is typically desirable to introduce medicament into the person's lungs to restore normal breathing patterns to the extent possible. For many years, this has been accomplished by the use of metered dose inhalers. The metered dose inhalers include a canister which contains medicament and a propellant, a metering valve which dispenses the medicament from the canister, an actuator body that receives the canister and which forms an opening for oral inhalation, and an actuator stem which receives medicament from the canister and directs it out the opening in the actuator body. Moving the medicament canister relative to the actuator body and actuator stem causes the metering valve to release the predetermined amount of medicament. Each metered dose inhalator is regulated by the U.S. Food and Drug Administration and each of the components is specifically designed relative to the parameters of the other components.
When the user is having difficulty breathing, the opening of the actuator body is placed in the user's mouth and then the canister is moved downwardly in the actuator so that the metering valve discharges the predetermined dose of medicament and propellant. The medicament passes through the actuator stem and then out the opening in the actuator body.
One problem which is recurrent in the use of metered dose inhalers is that the user often actuates the metered dose inhaler and then begins inhalation. Such an inhalation/medicating pattern limits the amount of medicament delivered to the lung and causes most of the medicament to impact the mouth and throat. Thus, the user obtains much less than an optimal dose of medicament.
In attempts to overcome the problems associated with manual actuation of the metered dose inhalers, several inhalation/breath actuated metered dose inhalers have been developed. Such devices are designed to provide proper coordination of dispensing a dose of medicament with the inhalation of the user, thus providing for the maximum proportion of the dose of medicament to be deposited in the lungs. Examples of such devices are described in U.S. Pat. Nos. 5,404,871; 5,347,998; 5,284,133; 5,217,004; 5,119,806; 5,060,643; 4,664,107; 4,648,393; 3,789,843; 3,732,864; 3,636,949; 3,598,294; 3,565,070; 3,456,646; 3,456,645; 3,456,644; British Patent Specification Nos. 2,061,116; 1,392,192; 1,335,378; 1,269,554 and German Patent No. 3,040,641.
Existing breath-actuated inhalers are designed to accommodate available aerosol canisters separate from the receiving bodies or housings for which they were originally designed, marketed, and approved by the Food and Drug Administration (FDA). Aerosol medications of the pressurized inhaler type are drug products approved and regulated by the FDA as the combination of the pressurized aerosol canister and the actuator used to atomize the canister metering valve contents. The actuator is regarded as an integral part of the aerosol drug delivery system, since the design of the housing greatly influences the nature of the aerosol spray generated for inhalation by the patient. The design of the actuator impacts not only the amount of medication released from the inhaler, but the amount of medication received by the patient due to the actuator's influence on the particle size and velocity distribution of the emitted aerosol mist and the influence of the particle or droplet size distribution and velocity on impaction in the patient's respiratory tract.
As a consequence, existing breath-actuated inhalers must be approved by the FDA in conjunction with a particular aerosol-based medication canister. As a result, these inhalers have not been generally available to the patient public for use with the full range of aerosol-based medications which are available for the treatment and management of disease. For example, a person must obtain a breath actuated device that has been approved by the FDA with the canister of medication recommended by the physician or the individual must obtain a metered dose inhaler of the desired medication, i.e., the combination of the medicament container and the actuator approved by the FDA.
A problem with many of the mechanical breath-activated inhalers is that the aerosol canister remains in the depressed position (after firing by the inhaler's internal actuation mechanism) until the patient physically intervenes and relieves the mechanical load on the aerosol canister by moving a lever, strap, or some other mechanical means. Immediately after venting, the metering chamber (valve) of the aerosol canister becomes vulnerable to the intrusion of air and the extent of air intrusion increases with the length of time the canister remains in the depressed position. The intrusion of air in this fashion can result in “vapor locking” of the metering valve, resulting in incomplete filling of the metering chamber of the valve when the canister is ultimately released from the depressed position. Incomplete filling of the metering chamber, in turn, results in incomplete dosing on the next actuation of the inhaler, due to the lower quantity of drug which has entered the metering chamber from the liquid contents of the canister.
Another problem associated with some mechanical breath-actuated inhalers is that the aerosol canister actuation mechanism must be in the “armed”, ready to fire, position in order to allow recovery of the aerosol canister from the depressed position under the action of it's own internal valve spring. Two potential consequences may result from this condition. First, the actuation mechanism may be “armed” during the intervals between inhaler use or, second and of potentially more seriousness, the actuator mechanism may be “armed” during storage. This is particularly concerning when the device, as a consequence of its sale in combination with an aerosol canister as mandated by the FDA, is packaged with an aerosol canister in place. Thus, the actuator mechanism could be in the armed position for up to three years. In either event, the functional life and reliability of the device may be compromised by the long term stress effects of maintaining the actuation mechanism in the “armed” position for extended periods.
In addition to the above, the actuator mechanism may “relax” or creep, in either a fluid or bulk mechanical sense, if the device is stored for prolonged periods in the “armed” position, resulting in a change in actuator functionality with effects that may range from “premature” firing of the aerosol canister to delayed or extended firing time during the canister depression phase. In both cases the patient does not receive the prescribed dose of medication which the inhaler was designed to deliver.
Electro-mechanical inhalers are also known. U.S. Pat. No. 5,347,998 describes a breath-actuated inhaler with an electromechanical priming mechanism. It is the object of the invention described therein to provide an inhalation device for use with pressurized aerosol canisters which does not require manual priming for firing the valve contained within the aerosol canister. Further, the
Casper Robert A.
Gardner David L.
Leith Frank A.
Lyon Zachary Wood
Snow John Medlin
Bateman IP Law Group
Dawson Glenn K.
Innovative Devices, LLC.
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