Surgery – Liquid medicament atomizer or sprayer
Reexamination Certificate
1999-12-21
2002-06-04
Weiss, John G. (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
C128S200230
Reexamination Certificate
active
06397838
ABSTRACT:
BACKGROUND AND OBJECTS OF THE INVENTION
This invention relates to devices and methods for delivering an aerosolized liquid to a user's lungs, and particularly an aerosolized liquid having therapeutic properties.
For some therapeutic agents, delivery of the aerosolized liquid without a propellant is preferred. Such liquids may be aerosolized, for example, by an electrohydrodynamic apparatus. The liquid to be aerosolized is made to flow over a region of high electric field strength, which imparts a net electric charge to the liquid. This electric charge tends to remain on the surface of the liquid such that, as the liquid exits the nozzle, the repelling force of the surface charge balances against the surface tension of the liquid, forming a cone (a “Taylor cone” as described in, e.g., M. Cloupeau and B. Prunet-Foch, “Electrohydrodynamic Spraying Functioning Modes: A Critical Review,”
J Aerosol Sci
., Vol. 25, No. 6, pp. 1021, 1025-1026 (1994)). In the region of the tip of the cone, which has the greatest charge concentration, the electrical force exerted on the liquid surface overcomes the surface tension, generating a thin jet of liquid. The jet breaks into droplets of more or less uniform size, which collectively form a cloud that may be inhaled by a user to deliver the aerosol to the user's lungs.
Dr. Ronald Coffee of Oxford University, Oxford, England, has proposed and developed methods of aerosolizing pharmaceutical formulations and discharging the aerosol particles prior to their delivery to a user. One such method uses an electrohydrodynamic apparatus having a single spray site (nozzle) surrounded by four discharge electrodes and a grounded shield to produce a monodispersed spectrum of particle sizes.
Known pulmonary delivery devices that use electrohydrodynamic spraying are unwieldy and require connection to either an alternating current power supply or a large direct current power supply. These conventional devices are suitable for use in hospital or other clinical applications, such as for administering a therapeutic agent during a scheduled treatment appointment, but generally are not suitable for use directly by a user on a demand or as-needed basis outside a clinical setting. Conventional devices are particularly unsuited for use during a user's regular activities at home, at work, while traveling, and during recreational and leisure activities.
Known pulmonary delivery devices that use electrohydrodynamic spraying also lack a sufficient volumetric flow rate to deliver a desired amount of certain therapeutic liquids during the inhalation of one to two breaths by a user. Attempts to increase the flow rate generally have resulted in even more bulky devices unsuitable for hand-held use. These delivery devices also are not generally capable of spraying liquids having a broad range of conductivities.
It is an object of the invention to provide a device and method that conveniently delivers an aerosolized liquid to a user's lungs. It is another object of the invention to provide a compact, portable, hand-held pulmonary delivery device that may be used in a variety of indoor and outdoor locations. The device would allow users to administer therapeutic agents on an as-needed basis in nonclinical settings and provide advantages over conventional devices used by hospitals and clinicians.
It is a further object of the invention to provide a compact and convenient device and method that delivers an increased volumetric flow rate of liquid so that a desired amount of a therapeutic liquid dispersed into respirable particles may be administered during the inhalation of one to two breaths by a user.
It is another object of the invention to provide a device and method capable of electrohydrodynamic spraying of therapeutic liquids having a broad conductivity range in a compact and convenient device.
It is yet another object of the invention to provide an apparatus for aerosolizing liquid that is useful in the delivery to a user, in the form of respirable particles, of a desired amount of a therapeutic liquid within a broad conductivity range.
SUMMARY OF THE INVENTION
The invention described here provides a compact, convenient device and method for delivering an aerosolized liquid having therapeutic properties to a user's lungs by electrohydrodynamic spraying. Preferably, the device is small enough that it can be comfortably carried by a user, for example, in shirt pocket or purse, and has a self-contained power supply so that it can be used anywhere. The device may be disposable. or reusable.
In a preferred embodiment, the pulmonary aerosol delivery device comprises a housing sized so that it can be held in a user's hand and having an exit opening for directing the aerosol to the user's mouth. The housing encloses a dispensing system for containing the liquid to be aerosolized and delivering it to an electrohydrodynamic apparatus, an electrohydrodynamic apparatus for aerosolizing the liquid and delivering the aerosol to the exit opening; and a power supply system for providing sufficient voltage to the electrohydrodynamic apparatus to aerosolize the liquid. The power supply system may comprise a battery and a DC to DC high voltage converter so the device may be cordless.
The liquid to be aerosolized may comprise a drug. The dispensing system of the device may include a containment vessel for containing the drug, which may be a holder for a drug enclosed in single dose units, a plurality of sealed chambers each holding a single dose of a drug, or a vial for enclosing a bulk supply of a drug. The containment vessel may have antimicrobial properties and may be capable of maintaining the sterility of a sterile drug placed therein.
The dispensing system delivers a single dose of the drug from the containment vessel to the electrohydrodynamic apparatus, which may be accomplished using a metering system. The metering system may include a chamber for collecting a predetermined volume of liquid having an inlet communicating with the containment vessel and an outlet communicating with the electrohydrodynamic apparatus; a chamber housing above the chamber; a chamber housing spring adjacent to the chamber; and a button spring above the chamber housing. The button spring exerts a downward force against the chamber housing when an actuator button is depressed to force liquid in the chamber through the outlet and the chamber housing spring exerts an upward force against the chamber housing when the actuator button is released. The upward travel of the chamber housing induces a vacuum in the chamber to draw liquid from the containment vessel through the inlet. The chamber volume is controlled by an adjustable stop that limits the upward travel of the chamber housing. The metering system may further include check valves at the chamber inlet and outlet to provide unidirectional liquid flow.
The device may further include a control circuit communicating with the dispensing system, the electrohydrodynamic apparatus and the power supply system. The control circuit may include an on/off power indicator, a power save feature, or a lockout to prevent use by an unauthorized user.
The control circuit may include an actuation device for initiating the flow of aerosolized liquid. The actuation device may be a breath sensor for detecting a user's inhalation of one or more breaths, such as a flapper switch, a pressure transducer, an air motion detector, or an air velocity detector, which cooperates with the electrohydrodynamic apparatus to initiate the flow of aerosolized liquid. The actuation device also may be a manual actuator on the exterior of the housing.
The electrohydrodynamic apparatus of the device may be capable of aerosolizing the liquid at a flow rate of at least about 20 &mgr;L/sec. It also may be capable of aerosolizing the liquid into droplets such that at least about 80% of the droplets have a diameter of less than or equal to about 5 microns.
The housing of the device may have antimicrobial properties. The exit opening of the housing may be movable to a
Busick David R.
Dvorsky James E.
Peters Richard D.
Zimlich, Jr. William C.
Battelle Pulmonary Therapeutics, Inc.
Mitchell Teena
Porter Wright Morris & Arthur LLP
Weiss John G.
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