Surgery – Respiratory method or device – Means for mixing treating agent with respiratory gas
Reexamination Certificate
2001-08-09
2003-01-14
Dawson, Glenn K. (Department: 3761)
Surgery
Respiratory method or device
Means for mixing treating agent with respiratory gas
C128S203280, C128S203220, C128S207180
Reexamination Certificate
active
06505622
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a system and method for dispensing liquid droplets or spray-pattern discharges, and relates more particularly to a system and a method for dispensing droplets or spray-pattern discharges of medicinal liquids into the nasal passage, which system and method provide greater ease of application and privacy for the user, as well as increased mechanical efficiency and improved ability to prevent contamination of the stored medicinal liquids.
BACKGROUND OF THE INVENTION
Amongst various dispensers for applying medicament, a typical medicament container includes a flexible vial storage portion and a nozzle for dispensing medicament by squeezing the vial between its side walls. Another type of medicament dispenser is an accordion-like or piston-like pump dispenser which is actuated by squeezing the vial between a bottom wall and the nozzle so as to compress the vial in its longitudinal direction, rather than from its sides. An example of the piston-like dispenser which ejects precalibrated dosage of medicament is described in detail in U.S. Pat. No. 5,613,957, which is expressly incorporated herein by reference.
In recent years, pump-type dispensers have received attention for their use in accurately dispensing small doses of medicaments, e.g., for nasal applications. One persistent problem associated with pump-type dispensers for dispensing medicaments is preventing contamination of the medicament which can occur when the medicament that has been exposed to ambient air returns and/or remains in the outlet channel, e.g., within the nozzle. One solution to this problem is to simply add preservatives to the medicament being dispensed, thereby preventing bacterial growth. However, this solution has obvious disadvantages, e.g., added costs and toxicity of the preservatives. In order to prevent bacterial growth in medicament which does not contain preservatives while allowing dispensation of multiple doses of the medicament, the nozzle must prevent any medicament that has been previously exposed to ambient air from being reintroduced, or “sucked back,” into the outlet channel of the nozzle, i.e., prevent any “dead volume.” “Dead volume” is defined herein as the volume of space within the outlet channel of the pump where medicament can come into contact with the open air and remain. If any residual medicament remains within the dead volume, this residue could serve as a host environment for germ growth.
Another consideration involved in designing pump-type dispensers for medicaments is ensuring accurate dispensation of a predetermined quantity of medicament, e.g., ranging from 5 &mgr;l to greater volumes, upon each actuation of the dispenser, irrespective of the orientation of the dispenser or the force applied by the user to the actuation mechanism of the dispenser. While many pump-type dispensers provide an upper limit of the quantity of medicament dispensed upon each actuation of the dispenser, these pumps often dispense varying quantities of medicament as a function of the speed and/or force of actuation of the actuation mechanism of the dispenser. In the case of a pump-type dispenser which generates aerosol or spray-type discharges, not only will the dispensed dose of medicament vary with the speed and/or the force of actuation of the actuation mechanism, but the spray pattern, or the plume, of the dispensed medicament will also vary with the speed and/or the force of actuation.
It should also be noted that persons who suffer from asthmatic or allergic condition routinely need to carry a medicament dispenser with them for emergency situations, but both the existing pressurized medicament dispensers and non-pressurized dispensers have significant drawbacks. The pressurized dispensers are not always ready for use unless they incorporate a heavy glass bottle sustaining vacuum. The non-pressurized devices generally require a particular orientation for dispensing medicament, as well as suffering from a measurable dead volume in the nozzle area.
Yet another problem in designing pump-type dispensers for medicaments is ensuring the ease of applying the medicament. Conventional pump-type dispensers for nasal application, an example of which is shown in
FIG. 2
, are generally actuated by compression along the length of the dispenser. As shown in
FIG. 2
, the conventional nasal pump
200
is actuated by pushing down on the syringe arms
203
while supporting the bottom portion
202
with the thumb. The combined actuation motion leads to difficulty in holding the nasal pump in stationary position, and usually results in removal of the nozzle tip
204
from the nostril area. For those users who may have greater than average difficulty with the actuation motion, e.g., elderly patients with arthritis or young children, accidental application of the nasal medicament to the face or into the eye may occur.
Yet another problem associated with the pump-type medicament dispensers is manufacturing complexity: pump-type medicament dispensers are currently made of numerous parts and are highly delicate to assemble. As the number of components increases, the difficulty and cost of mass production increases correspondingly. For example, many of the pump-type dispensers incorporate springs, which pose problems in the manufacturing process because of the springs' tendency to get intermingled. In addition, very small size of the gaskets and other components make relative movement of the parts difficult. Furthermore, increased number of components also increases the complexity of achieving stability and compatibility of the component materials with the medicament.
One attempt to solve the above-described problems associated with applying medicament from a dispenser is described in my U.S. Pat. No. 5,267,986, which discloses a system including a cartridge for actuating a piston-like or accordion-like vial-dispenser for applying medicament to an eye. The cartridge disclosed in U.S. Pat. No. 5,267,986 includes: a housing for holding the vial-dispenser; a telescoping cylinder for compressing the vial-dispenser in the longitudinal direction to load the vial with medicament; a locking mechanism for locking the telescoping cylinder and the vial-dispenser in the loaded position, against the urging of a spring mechanism of the vial-dispenser; and a trigger mechanism for releasing the telescoping cylinder and the vial-dispenser from the locked position to release the medicament loaded in the dispenser by means of the force of the spring mechanism. In order to obviate the need for a discrete spring element in the pump mechanism of the vial-dispenser, a portion of the vial-dispenser body is made of an elastic material which is compressible and provides spring force. The two-step process in which the cartridge disclosed in U.S. Pat. No. 5,267,986 loads and subsequently releases the medicament from a vial-dispenser defines the basic operation a “reverse pump,” an example of which is described in U.S. Pat. No. 5,613,957.
The dispensing system disclosed in U.S. Pat. No. 5,267,986 addresses some of the previously-mentioned problems by enabling a user to apply a predetermined dose of medicament independent of the physical force, or speed, applied to the dispensing system by the user: the releasing force or speed of the dispensed medicament is dependent on the integral spring element of the dispensing system. Whereas conventional pump-type dispensers often utilize compression along the longitudinal axis-for release of medicament, the actuation motion of the release mechanism described in U.S. Pat. No. 5,267,986 is preferably achieved in a direction perpendicular to the longitudinal axis of the vial-dispenser to ensure enhanced leverage for the user.
While the dispensing system disclosed in U.S. Pat. No. 5,267,986 addresses some of the previously-mentioned problems, at least one significant problem remains: because elastic materials, particularly elastomeric materials and springs, tend to exhibit hysteresis, spring force decreases if the spring mechanism is kept in the c
Dawson Glenn K.
Kenyon & Kenyon
Mendoza Michael
LandOfFree
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