Capillary aerosol technology and capillary aerosol generators have been described in U.S. Pat. No. 5,743,251, the contents of which are hereby incorporated by reference in their entirety.
In accordance with one embodiment, a method of dispensing a liquid or aerosol to maintain a clog free capillary system, comprises: supplying a liquid formulation from a pumping unit to a capillary of an aerosol generation unit at a flow rate; and periodically increasing the flow rate from a first flow rate to a second flow rate.
In accordance with another embodiment, a method of dispensing a liquid formulation in a drug delivery system to an aerosol generation unit, comprises: supplying a liquid formulation from a pumping unit to a capillary of an aerosol generation unit at a flow rate, the pumping unit having two syringe pumps and a valving arrangement operable to supply the liquid formulation into an inlet of one syringe pump during delivery of liquid formulation to the aerosol generator unit by the other syringe pump; vaporizing at least a portion of the liquid formulation within the capillary of the aerosol generation unit; and increasing the flow rate from a first flow rate to a second flow rate at least once per each syringe cycle.
In accordance with a further embodiment, a system for maintaining a clog free capillary comprises: an aerosol generation unit having a capillary passage; a liquid formulation; a pumping unit, which supplies the liquid formulation to the aerosol generation unit at a flow rate, wherein at least a portion of the liquid formulation is vaporized within the capillary of the aerosol generation unit; and a controller, which operates the pumping unit to provide for periodic increases in the flow rate for clog prevention.
In accordance with a further embodiment, a method of dispensing a fluid from a fluid source comprises: supplying a fluid to a pumping unit having a first syringe pump and a second syringe pump, each syringe pump having an aspirating valve and a discharge valve; discharging the fluid from the first syringe pump by closing the aspirating valve and opening the discharge valve; and aspirating the second syringe pump by opening the aspirating valve and closing the discharge valve to draw the fluid into the second syringe pump.
Aerosols are useful in a wide variety of applications. For example, it is often desirable to treat respiratory ailments with, or deliver drugs by means of, aerosol sprays of finely divided particles of liquid and/or solid, e.g., powder, medicaments, etc., which are inhaled into a patient's lungs. Aerosols can be generated from a heated capillary aerosol generator by feeding a solution or suspension in a liquid state to a capillary while heating the capillary sufficiently such that the solution (or the carrier portion of the suspension) is volatilized, so that upon discharge from the heated capillary, the solution (or suspension) is in the form of an aerosol. The aerosol generating system can be used to aspirate a liquid material or formulation, and dispense it through an aerosol generator or capillary passage sub-assembly for delivery of a continuous aerosolization.
Referring to
As shown in
It can be appreciated that when dispensing certain liquids through the capillary passage, with or without the intent to aerosolize, the properties of the liquid or liquid formulation may cause a coating, agglomeration, or deposits to form on the inside of the capillary passage. In addition, accumulation of such material within the capillary or capillary passage can also lead to clogging of the capillary or capillary passage. Accordingly, it would be desirable to have a system and method of modulating or changing the flow of the liquid formulation periodically to enable a cleaning or flushing of any potential material within the system. The modulating or changing of the flow of the liquid formulation can also maintain a stable nominal operating pressure for the system and provide a reliable aerosol of consistent quality.
In accordance with one embodiment, an aerosolization system or drug delivery system 10 having improved reliability and the robustness of a capillary aerosol generation system, can be obtained by modulating or changing the flow of the aqueous or liquid formulation 50 for a short duration to enable cleaning or flushing of any potential material within the capillary or capillary passage 42. In an aerosolization system or drug delivery system 10 as shown in
When the aerosol is generated, the system 10 can generate significant backpressure in the order of 1100 to 1200 psi, due to vaporization of the aqueous or liquid formulation 50 and the pumping of the vapor/liquid formulation 50 through a reduced orifice or tipped capillary at the exit of the aerosol generation unit 40. Large particles in the aqueous or liquid formulation 50, and sub optimal vaporization can also cause a gradual increase in pressure in the system up to 3000 to 3500 psi, at which point the material (or clogging particles) either is ejected from the capillary passage or irreversibly clogs the capillary or capillary passage 42.
In accordance with an embodiment, a method of dispensing a liquid formulation in a drug delivery system to an aerosol generation unit 40, includes the steps of dispensing a liquid formulation 50 to a pumping unit 30; supplying the liquid formulation 50 from the pumping unit 30 to a capillary 42 of an aerosol generation unit 40 at a first flow rate; vaporizing at least a portion of the liquid formulation 50 within the capillary 42 of the aerosol generation unit 40; and periodically increasing the flow rate from a first flow rate to a second flow rate. The flow rate returns to the first flow rate after each of these short durations of increased flow. In accordance with a preferred embodiment, the second flow rate is preferably at least twice the first flow rate. It can also be appreciated that by increasing the flow rate within the system 10, the system 10 experiences an increase in the operating pressure within the capillary passage of the aerosol generation unit 40.
In use with the system 10 as shown in
In a preferred embodiment, the periodic increase in flow rate within the capillary or capillary passage does not include any reduction in pressure within the capillary. It can be appreciated that a reduction in pressure within the capillary can lead to clogging of the capillary 42. Accordingly, the increase in flow rate preferably coincides with the maintenance of the pressure within the capillary 42 and/or an increase in pressure within the capillary 42.
In accordance with an embodiment, the system 10 is a continuous delivery system, wherein the pumping unit 30 continuously delivers the liquid formulation 50 to the capillary or capillary passage 42 via a valving arrangement 60. As shown in
The valving arrangement or valve assembly 60 includes an inlet 110, which can be connected to a source of a liquid formulation or liquid material 50, first and second flow paths 121, 123 in fluid communication with the inlet 110, and an outlet 124 in fluid communication with an inlet of the aerosol generator unit 40. As shown in
More particularly, now referring to
Referring specifically to
Referring to
Referring now to
It is to be realized that as the second syringe pump 72 completes its discharge stroke, the first syringe pump 70 will have already completed its aspirating stroke and will have initiated its discharge stroke in accordance with handshake parameters. At that point the flow through the system will resemble that shown in
For example, in accordance with one embodiment, a pumping unit 30 dispenses the liquid formulation 50 at approximately 20 microliters per second (μl/s) to a valving assembly 60 for delivery to the capillary or capillary passage 42. The valving assembly 60 includes a pair of syringes 70, 72, wherein one syringe 70 dispenses for fifty seconds, after which it refills and the other syringe 72 dispenses for fifty (50) seconds. Thus, the natural periodic handshake of syringes 70, 72 every fifty (50) seconds can be taken advantage of as a convenient opportunity to increase the liquid formulation 50 flow rate from 20 to 40 microliters per second (μl/s) for a short duration.
In accordance with another embodiment, the increase in flow rate can be accomplished by dispensing from the second syringe 72 while the first syringe 70 is still dispensing. In particular, an overlap or increase in flow rate can occur for between two (2) to four (4) seconds. In addition to increasing or doubling the flow rate, the system 10 also preferably pressurizes the fluid or liquid formulation 50 in the syringe to a value close to the operating pressure before the syringe begins dispensing the liquid formulation 50 to the aerosol generator 40.
In an alternative embodiment, a single syringe pump unit 30 can be used, wherein the flow rate is increased as part of the delivery cycle. In accordance with a single syringe pump system, the system 10 has a defined fill cycle, upon which a short burst or periodic increase in the flow rate increases the operating pressure and ejecting any material that may be accumulated inside the capillary or capillary passage 42.
It can be appreciated that the timing of the periodic increase in flow can be a function of the properties or concentration of the liquid material or formulation 50, the flow rate, and the aerosolization parameters. For example, a liquid material or formulation 50 having a higher concentration (of medicaments or other materials) will preferably require more frequent increases in flow rate (i.e., flushes) than a liquid formulation 50 having a lower concentration.
In accordance with another embodiment, the modulating or changing of the first flow rate to a second flow rate can be performed in a plurality of short bursts, wherein each of the plurality of short bursts occurs for less than one second at a frequency of one burst every 10 seconds or less. In addition, it can be appreciated that by increasing the flow rate, an increase of 10 to 20 percent in the operating pressure within the system can be achieved, which can prevent the build up of any significant amount of large accumulation inside the capillary 42.
An example of the benefit and effectiveness of a periodic increase in flow rate in an aerosolization system is shown in
While various embodiments have been described, it is to be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto.
This application is a divisional application of U.S. application Ser. No. 12/285,314, filed Oct. 1, 2008 for DISPENSING METHOD AND SYSTEM OF A CAPILLARY AEROSOL GENERATOR which claims priority under 35 U.S.C. §119(e) to U.S. Patent Provisional Application No. 60/976,991, filed Oct. 2, 2007, the entire content of each is incorporated herein by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
60976991 | Oct 2007 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12285314 | Oct 2008 | US |
Child | 14657489 | US |