Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Patent
1994-05-04
1995-11-28
Burr, Edgar S.
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
12820312, 604 58, A61M 1500
Patent
active
054698430
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to dry powder inhalation devices.
DESCRIPTION OF THE RELATED ART
Asthma and other respiratory diseases have long been treated by inhalation of medicament. For many years, the two most widely used and convenient choices of treatment have been inhalation of medicament from a drug solution or suspension in an aerosol propellent from a metered dose pressurized inhaler, or inhalation of powdered drug, generally admixed with a powdered excipient, from a dry powder inhaler. With growing concern being voiced over the strong link between depletion of the earth's ozone layer and chlorofluorocarbon emissions, the use of these materials as aerosol propellants in pressurized inhalers is being questioned and interest in dry powder systems has been stimulated.
Most single and multiple dose dry powder inhalers use either individual premeasured doses of medicament which are inserted into a dispensing chamber prior to use, or they incorporate a bulk powder reservoir from which successive quantities of medicament are transferred to the dispensing chamber. Such inhalers generally comprise an air passage leading from the dispensing chamber which terminates in a patient port adapted to be inserted into the mouth or nasal passage of the patient. Patient inhalation .at the patient port generates an air stream through the dispensing chamber which carries particles of medicament into the lungs of the patient.
Examples of such dry powder inhalers are disclosed in U.S. Pat. Nos. 2,587,215, 3,669,113, 3,948,264, 3,971,377, 4,046,146, 4,098,273, 4,137,914, 4,147,166, 4,192,309, 4,240,418, 4,674,491, 4,846,168; British Patent Nos. 1,118,341, 1,268,051, 1,526,303, 2,041,763, 2,061,735, 2,165,159, and 2,191,718; European Patent No. 237507 and International Patent No. WO 90/07351.
A problem common to many dry powder systems is the tendency of the powdered medicament to agglomerate. Agglomeration is caused by individual particles of medicament adhering together in a semi-rigid mass, and requires an increased inspiratory effort by the patient to separate and entrain drug particles into the air stream. If the patient is unable to provide sufficient inspiratory effort the extent of drug penetration into the lower airways of the lung will be reduced. Larger agglomerated drug particles (>10 .mu.m) which result from inefficient aerosolization are not stably entrained into the patient's air stream and prematurely deposit in the mouth or throat region which may lead to unwanted systemic side effects, especially when potent drugs are administered.
It is desirable to utilize the action of the patient's breathing both to deagglomerate and aerosolize the powdered drug, thereby overcoming the coordination problems necessary to synchronize inhalation with means for medicament aerosolization. The efficiency of powder aerosolization, however, is solely determined by the patient's inspiratory effort. Consequently, a patient having difficulty breathing, e.g., during an asthma attack, may possess insufficient inspiratory effort to deagglomerate and aerosolize the medicament and inhale the required dose at a time when the patient has the greatest need for the .drug.
Many inhalation devices have attempted to solve the problems attributable to powder agglomeration by incorporating into the device deagglomeration and aerosolization means, e.g., a battery-powered solenoid buzzer, which cause or assist deagglomeration and aerosolization of the powdered medicament by breaking up particle agglomerates entirely independent of the patient's inspiratory effort. Examples of such devices are disclosed in, e.g., U.S. Pat. Nos. 3,948,264, 3,971,377, and 4,147,166. The device may be made fully independent of the patient by incorporating a breath actuation mechanism responsive to respiratory flow, which is able to synchronize medicament release with patient inhalation. An example of such a device is disclosed in our copending International Patent Application No. 90/00670 filed on 30th Apr. 1990.
Dry powder inhalers are also
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Burr Edgar S.
Deane, Jr. William J.
Griswold Gary L.
Hulse Dale E.
Kirn Walter N.
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