Inhaler apparatus using a tribo-electric charging technique

A tribo-inhaler having a container portion for electrostatically retaining a predefined dose of medicament powder, where the medicament is tribo-electrically charged; and apparatus, attached to the container portion, for extracting said medicament powder from the container portion. The container portion contains a plurality of polymeric beads that have diameters of approximately 50 to 200 microns. Each of the polymeric beads has a specific quantity of dry powder medicament electrostatically adhered to its surface. To remove the medicament from the cavity, a patient merely inhales air through the container portion. The air flow forcefully moves the beads within the container portion causing the medicament to dislodge from the beads and be carried by the air flow into the lungs of the patient.

The invention relates to medication inhalers and, more particularly, to 
apparatus for electrostatically retaining a medicament powder within an 
inhaler using a tribo-electric charging technique. 
BACKGROUND OF THE DISCLOSURE 
Inhalers are used to administer pre-determined quantities (doses) of 
inhalable dry powder medicament to the lungs of a patient. Generally, 
inhalers are mechanical systems that generate a metered cloud of 
medicament that is inhaled by a patient. Many of these prior art inhaler 
devices use chloroflourocarbon (CFC) gas to facilitate generation of the 
metered cloud of medicament. However, since CFCs are no longer used in 
consumer products, other techniques for generating the medicament cloud 
have been explored. 
One example of a non-CFC, prior art inhaler is disclosed in U.S. Pat. No. 
4,811,731 issued Mar. 14, 1989 (the "'731 patent"). This patent discloses 
an inhaler that contains a plurality of measured doses of medicament 
stored in a blisterpack. Upon use, one of the blisters in the blisterpack 
is punctured and a patient inhales the medicament from the punctured 
blister via a mouthpiece of the inhaler. In the '731 patent, the 
medicament dosage varies with the amount of force with which the patient 
inhales. Since inhalation of a powder from a blisterpack is rather 
difficult and a patient does not repeatedly inhale with the same force 
each time the medication is taken, the medicament dosage that is actually 
consumed can vary greatly from dose to dose. 
Therefore, a need exists in the art for an inhaler that, over a wide range 
of inspirable flow rates, maximizes drug propagation to the lungs and 
provides, with each use of the inhaler, substantially identical doses of 
medicament to the lungs. 
SUMMARY OF THE INVENTION 
The present invention overcomes the disadvantages associated with prior art 
inhalers by using a tribo-electric charging technique to retain a 
medicament powder within an inhaler apparatus. This unique inhaler 
apparatus has been dubbed a tribo-inhaler. The tribo-inhaler comprises a 
container portion within which is electrostatically retained a predefined 
dose of medicament powder, where the powder is tribo-electrically charged, 
and a mouthpiece or inhalation tube, attached to the container portion, 
for extracting the medicament powder from the container portion.

DETAILED DESCRIPTION 
The present invention is an inhaler apparatus containing one or more 
predefined doses of medicament powder. The invention retains each dose 
within a container portion by an electrostatic charge generated using a 
tribo-electric charging technique. 
Specifically, FIG. 1 depicts a partial sectional view of a first embodiment 
of the tribo-inhaler 100. The tribo-inhaler contains a housing 102 having 
a container portion 104 for retaining a medicament powder, and a flexible 
inhalation tube 106, attached to the housing, for extracting the 
medicament from the container portion. The container portion defines at 
least one cavity 108. Each cavity is an aperture 110 that passes through 
the container portion. The illustrative container portion 110 contains a 
plurality of cylindrical apertures that are evenly distributed in a 
circular pattern near the circumferential edge of the container portion. 
Medicament powder 112 is electrostatically retained within each cavity. 
The container portion is moveable relative to the housing, e.g., in 
response to user manipulation, the container portion rotates about a 
central axis 120 thereof (indicated by arrow 116). More specifically, the 
container portion is disk-shaped and is rotatable within the housing such 
that any one of the cavities can be positioned proximate one end (an inlet 
end 114) of the inhalation tube. The inhalation tube has its inner surface 
coated with a material, such as Teflon, that reduces adhesion of the 
medicament to the tube as the medicament passes through the tube. 
Additionally, the inhalation tube is generally flexible such that it 
easily folds along the top of the housing. As such, the inhaler easily 
fits within a shirt pocket or purse. 
In use, a patient inhales through the outlet end 118 of the inhalation tube 
106 to withdraw medicament from a selected cavity. To inhale subsequent 
doses, the container portion is rotated to position a different, unused 
cavity proximate the inlet end of the tube. Alternatively, a metered 
quantity and flow rate of compressed air could be applied to the cavity to 
transport the medicament to the patient's lungs. 
More specifically, FIG. 2 depicts a cross-sectional view of a single cavity 
108 of the tribo-inhaler 100 taken along line 2--2 of FIG. 1. The cavity 
is essentially a cylindrical aperture 110 through the container portion 
104. The first and second ends 200 and 202 of the aperture are 
respectively enclosed by a first and second screen 204 and 206. Each 
screen is approximately 200 mesh. Alternatively, the screens could be 
perforated solid layers of plastic or metal having openings with diameters 
of approximately 5 to 10 microns. 
The cavity contains at least one, and more typically, a plurality of beads 
208. The surface of each bead is coated with a medicament powder 112. The 
powder adheres to the bead surface by electrostatic attraction generated 
by a tribo-electric charging technique. The process and apparatus used to 
tribo-electrically charge the beads and powder is discussed below with 
respect to FIG. 3. 
The container portion is fabricated by forming, typically by drilling, 
evenly spaced apertures in a disk-shaped substrate. Typically, the 
substrate is manufactured of plastic. Alternatively, the container portion 
is manufactured of injection molded plastic and the cavities are formed by 
the mold. Screen 206 (lower screen) is affixed to the surface of the 
container portion to close second aperture end 202. A select number of 
medicament coated beads are placed into the cavity, then the first screen 
204 (upper screen) is affixed to the container portion surface to close 
first aperture end 200. The screens are typically affixed by an adhesive 
such as epoxy. 
When a cavity is positioned proximate the inlet end of the inhalation tube 
and air is inhaled therethrough, air passes through the second screen, the 
cavity, and the first screen. As the air passes through the cavity, the 
beads are carried upwards until they impact the first screen. Since the 
beads impact the screen with substantial force, the medicament coating is 
dislodged from the surface of the beads. The dislodged medicament enters 
the inlet end of the inhalation tube as a cloud of medication and the tube 
carries the medicament to the patient that had inhaled on the outlet end 
of the inhalation tube. In this manner, a metered dose of medication is 
delivered to the patient's lungs. 
FIG. 3 depicts apparatus for tribo-electrically charging a medicament 
powder 112 so that the powder adheres to a plurality of beads 208. 
Specifically, the apparatus contains an enclosed bead container 300 having 
a lid 302, a plurality of beads 208, and a medicament powder 112. The 
beads and powder are mixed by shaking the container for one to ten 
minutes. During this period, the powder becomes tribo-electrically charged 
and the powder 112 electrostatically adheres to the beads 208. 
More specifically, the beads have a diameter of between 50 and 200 microns 
and are fabricated of one of the following materials Teflon, 
polyvinylidene fluoride, polypropylene, dyed polypropylene, flouro-treated 
glass, glass, amino-treated glass, polystyrene, titanium dioxide-filled 
polyethylene and the like. In use, the medicament and beads are added to 
the container 300, the lid of the container is closed and the beads and 
medicament mixture is shaken for one to ten minutes. During the shaking 
process, a charge accumulates on the particles of the powder. Once 
charged, the medicament particles uniformly coat the surface of each bead. 
The amount and polarity of the charge on the medicament particles depends 
upon the fabrication material of the beads. By measuring the 
charge-to-mass ratio of the powder using a faraday cage, the inventors 
have found that by selecting a particular bead material the charge 
characteristics are controllable. For example, charging a mometasone 
furoate (MF) powder in a glass container using four beads having 100 
micron diameters at 70 degrees Fahrenheit and 45% relative humidity, 
resulted in the charge-to-mass ratios for various bead materials shown in 
TABLE 1. 
TABLE 1 
______________________________________ 
Charge-to-mass ratios for various bead materials 
Bead Material Charge Polarity 
Ratio (.mu.C/gm) 
______________________________________ 
Teflon positive 35 
Polyvinylidene fluoride 
positive 30 
Polypropylene positive 6.5 
Dyed polypropylene 
positive 10 
Flouro-treated glass 
positive 17.8 
Glass negative 6.5 
Amino-treated glass 
negative 39.8 
Polystyrene negative 42.7 
Titanium dioxide-filled 
negative 7.7 
polyethylene 
______________________________________ 
By appropriate selection of the bead material, the charge-to-mass ratio can 
be varied from 6.5 to 43 mC/gm and the charge is either positive or 
negative. When retaining a medicament, a low microgram quantity of 
medicament (e.g., 2-10 mg) requires a relatively high charge-to-mass ratio 
and a high microgram quantity of medicament (e.g., 20-40 mg) requires a 
relatively low charge-to-mass ratio. Thus, flexible charging 
characteristics are useful in facilitating retention of a wide range of 
medicament dosages. 
Once the beads are coated with medicament, the coated beads are placed into 
a cavity of the container portion. A specific dose of medicament is 
defined by selecting a particular number of coated beads for placement in 
the cavity. When the medicament is dislodged and inhaled, a metered dose 
of medication is inhaled by the patient. 
FIG. 4 depicts an exploded, perspective view of a second embodiment of the 
inventive tribo-inhaler 400. FIG. 5 is a cross-sectional view of the 
inhaler 400 taken along line 5--5 of FIG. 4. To best understand this 
embodiment of the invention, the reader should consult both FIGS. 4 and 5 
while reading the following disclosure. 
The inhaler 400 is an assembly having three main components; namely, a 
cover portion 402, a medicament container portion 404, and a outer housing 
406. Each of the components is typically fabricated of injection molded 
plastic. The cover portion contains, affixed centrally to its top surface, 
a knob 414 and, affixed centrally to its bottom surface, a shaft 416. The 
shaft extends through a central bore 418 of the container portion 404 and 
is press fit therein. Additionally, the shaft rotatably extends through a 
central bore 420 in the outer housing 406. An end cap 422 is affixed, by 
gluing, welding, and the like, to the end of the shaft 416 such that the 
shaft can not be removed from the bore 420 but freely rotates therein. The 
cover portion and container portion rotate with respect to the outer 
housing about a central, longitudinal axis 436 of the shaft. 
The medicament container 404 is substantially cylindrical and contains one 
or more cavities 408. Each cavity is substantially triangular in plan form 
having three walls and a bottom, where the top of the cavity is open to 
allow for the tribo-electrically charged beads (not shown) carrying the 
tribo-electrically charged medicament to be placed in the cavity. The 
bottom of the cavity contains an air inlet hole 424 that is covered with a 
mesh screen 426 having a mesh size that permits air to pass into the 
cavity but retains the beads within the cavity 408 (e.g., a mesh size of 
approximately 200 mesh). An outer circumferential wall 410 that forms one 
wall of each cavity defines a medicament extraction hole 412 into each 
cavity. These holes are covered by a mesh screen 428 located inside each 
cavity. Mesh screen 428 has a mesh size that retains the beads in the 
cavity, but permits the medicament to be extracted from the cavity (e.g., 
a mesh size of approximately 200 mesh). 
The shaft 416 is press fit into bore 418 such that when knob 414 is 
rotated, the medicament container portion 404 rotates with respect to the 
outer housing 406. The outer circumferential edge of the cover portion 
interfits a lip 438 located on the upper edge of the wall 410. The 
interfit of the cover portion and the container portion seals each cavity 
such that air may only ingress and egress the cavity through the screens. 
To facilitate a sufficient seal, an adhesive may be applied about the lip 
to affix the edge of the cover portion to the lip. 
The outer housing contains a cylindrical outer wall 430 supported by a 
bottom portion 432. The bottom portion defines an air intake hole 434 that 
is positioned at a radial distance from the longitudinal axis 436 of the 
shaft that is equivalent to the radial distance of the air inlet hole 424 
from the longitudinal axis of the shaft. As such, the air intake hole 434 
can be aligned with a selected air inlet hole 424 by rotating the knob 
414. 
Additionally, the outer housing 406 contains an inhalation tube in the form 
of a mouthpiece 438 that extends from the outer wall 430. The mouthpiece 
bore has an inlet end 448 and an outlet end 446. The mouthpiece contains a 
bore 440 that extends longitudinally through the mouthpiece and through 
the wall 430. The mouthpiece bore 440 is aligned with the medicament 
extraction hole 412 located in the container portion 404. As such, by 
manipulating the knob, a particular cavity can be rotated into alignment 
with the mouthpiece. Alignment being defined as a cavity position that 
aligns the air inlet hole 434 with an air intake hole 424 and aligns a 
medicament extraction hole 412 with the mouthpiece bore 440. Once 
alignment has been attained for a selected cavity, a user (patient) 
inhales on the mouthpiece, drawing air through the air inlet and air 
intake holes and through the cavity. As the air passes through the cavity, 
the beads are moved toward extraction hole 412 and impact the screen 428. 
The impact dislodges the medicament from the beads, where the medicament 
is carried by the air flow through the mouthpiece bore and into the user's 
lungs. To facilitate alignment and use of particular cavities, the cover 
portion is typically labeled with cavity numbers (not shown) and each 
cavity has an associated alignment mark 442. To achieve alignment, a 
selected cavity's alignment mark 442 is aligned with a reference mark 444 
on the mouthpiece or some other indicia of alignment. Alternatively, 
alignment can be achieved using a mechanical lock mechanism that engages a 
detent when alignment with a particular cavity is achieved. 
Although various embodiments which incorporate the teachings of the present 
invention have been shown and described in detail herein, those skilled in 
the art can readily devise many other varied embodiments that still 
incorporate these teachings.