Title of Invention	NEEDLELESS INJECTION DEVICE WITH DOUBLE STOPPER WITH LOW PRESSURE PROFILES
Abstract	The present invention relates to a needleless injection device (1) comprising a reservoir (3), obturated by an upstream stopper (4) and a downstream stopper (5) between which a liquid active principle (6) is accommodated, and a receptacle (7) comprising at least one injection conduit (8), said receptacle comprising a cavity (10) whose height is equal to the distance travelled by the downstream stopper before each injection conduit is opened, - the height of the cavity in millimeters being between a minimum height and a maximum height, respectively defined by the following relationships, • minimum height = 3, • maximum height = 15 x exp. (-(V/9)2) +10, where V is the initial speed of ascent of the pressure profile expressed in bar per microsecond, - the ratio between the length of each injection conduit and the height of the cavity being between 1 and 2.

Title of Invention

NEEDLELESS INJECTION DEVICE WITH DOUBLE STOPPER WITH LOW PRESSURE PROFILES

Abstract

The present invention relates to a needleless injection device (1) comprising a reservoir (3), obturated by an upstream stopper (4) and a downstream stopper (5) between which a liquid active principle (6) is accommodated, and a receptacle (7) comprising at least one injection conduit (8), said receptacle comprising a cavity (10) whose height is equal to the distance travelled by the downstream stopper before each injection conduit is opened, - the height of the cavity in millimeters being between a minimum height and a maximum height, respectively defined by the following relationships, • minimum height = 3, • maximum height = 15 x exp. (-(V/9)2) +10, where V is the initial speed of ascent of the pressure profile expressed in bar per microsecond, - the ratio between the length of each injection conduit and the height of the cavity being between 1 and 2.

Full Text	Needleless injection device with double stopper with low pressure profiles The technical field of the invention is that of prefilled, disposable needleless injection devices, operating with an energy source such as, for example, a gas generator and used for intradermal, subcutaneous and intramuscular injections of a liquid active principle for therapeutic use in human or veterinary medicine. The active principle consists of a more or less viscous liquid, a liquid mix, or a gel. The active principle may also be a solid in solution in a solvent suitable for injection, or consist of a powdery solid suspended at a certain concentration in an appropriate liquid. The particle size of the active principle must therefore be compatible with the diameter of the ducts to avoid blocking them. As used in the present application, the term 'liquid active principle' constitutes the generic definition covering all the previously mentioned embodiments of the active principle. Needleless injection devices comprising a reservoir of liquid active principle already exist in tube form and have been the subject of patents. For example, the patent application FR 2 853 837 may be cited, which relates to a needleless injection device comprising an injection nozzle and a tube intended to receive a liquid active principle to be injected, said tube being fixed to said nozzle with the help of connecting means. The person skilled in the art traditionally seeks to minimize or even eliminate the risks of damaging, on the one hand, the tube containing the liquid active principle and, on the other hand, the downstream stopper in the specific Mouble stopper' configuration described, in particular, in the patent application WO 01/58512. Said configuration is characterized by the presence of a column of liquid delimited, on the one hand, by the side wall of the tube and, on the other hand, by an upstream stopper and a downstream stopper, between which the liquid active principle is housed. Under the effect of the gas generation, said column moves in the tube until the downstream stopper comes into contact with the base of a receptacle located in the nozzle so as to free the injection ducts in order to expel said active principle. However, when the downstream stopper hits the base of said receptacle, it creates a Shockwave that will propagate through to the tube and the intensity of which is a maximum at the end of said tube which is in contact with the nozzle. In a 'double stopper' configuration, the downstream stopper and the glass tube are the two most stressed elements during the operation of the needleless injection device. The latter must consequently be shaped in such a way that the speed of impact of the downstream stopper in the receptacle is less than the limit speed acceptable for the mechanical strength of the components of said injection device. In addition, it is known that the time separating the opening of the injection ducts and the start of the output of the jet from the injection ducts must be longer than the attenuation time of the pressure oscillations generated by the opening of the injection ducts. In the technical literature of the field in question it is traditionally mentioned that it is necessary to apply, to the liquid active principle to be injected, on the one hand a high pressure between 200 and 500 bar in order to pierce the skin, and on the other hand a constant or decreasing pressure through to the end of the injection in order to ensure the transfer of the liquid active principle, the final values generally being between 40 and 250 bar. However, there is a major stake in reducing the operating pressures so as to construct strong and economical needleless injection devices, more particularly for single-use devices or the consumable parts, such as the injection nozzle, of reusable devices while guaranteeing good reproducibility of injections. It has been surprisingly observed that the subject of the present invention precisely enables excellent needleless injection results to be attained with pressure profiles with initial values between 50 and 150 bar, preferably between 70 and 100 bar, i.e. values clearly lower than those commonly accepted in the field considered. More precisely, the subject of the present invention relates to a needleless injection device comprising an energy source such as a gas generator, a reservoir blocked by an upstream stopper and a downstream stopper between which a liquid active principle is housed, and an injection nozzle equipped with a receptacle and with at least one injection duct, said receptacle containing a cavity with a height equal to the distance covered by the downstream stopper before opening each injection duct, characterized in that it is shaped such that: the height of the cavity in millimeters is between a minimum height and a maximum height respectively defined by the following equations: • minimum height =3 • maximum height = 15 x exp(-(V/9)2)+10 where V is the speed of the initial increase in the pressure profile expressed in bars per microsecond; - the ratio between the length of each injection duct and the height of the cavity is between 1 and 2. The speed of the initial increase in pressure will be understood to involve the calculation of dP/dt throughout a period of time going schematically from 0 to 0.5 millisecond. In addition, with a needleless injection device according to the invention it is possible to obtain pressure profiles that are not necessarily flat or uniformly decreasing, in contrast to what is commonly accepted today in the literature. Even if several parameters such as the number and the diameter of the orifices in the injection ducts, or the quantity of liquid active principle, play a part in controlling the injection depth, a crucial advantage of the invention lies in the fact that the large variety of permitted shapes of pressure profile, depending on the type of energy source used, ensures fine and optimized management of the injection depth. Moreover, another considerable advantage of a needleless injection device according to the invention is the fact that it has been observed that the final pressure has no influence on performance as long as it is greater than 20 bar, which should be compared with the final values of 40 to 250 bar commonly accepted in the literature. Advantageously, the minimum height of the cavity in millimeters is defined by the following equation: • minimum height = 12 x exp(- (V/18)2)+4. Again advantageously, the maximum height of the cavity in millimeters is defined by the following equation: • maximum height = 14 x exp(-(V/9)2)+9. Preferably, the ratio of the length of each injection duct and the height of the cavity is between 1.1 and 1.6. Again preferably, the needleless injection device according to the invention is shaped in such a way that the time for an increase in pressure to 80 bar is schematically between 0.2 and 2.0 milliseconds. Advantageously, the energy source consists of a pyrotechnic gas generator equipped with a pyrotechnic charge and an ignition system. The invention will be better understood with the help of the detailed description set out below with regard to the appended drawing in which: figure 1 is a schematic longitudinal cross section view of a needleless injection device according to the invention; - figures 2 to 5 show examples of pressure profile curves obtained as a function of the velocity of the energy source used. A needleless injection device 1 according to the invention, as shown in figure 1, comprises a body 2 in which a reservoir 3 containing a liquid active principle 6 is housed. An injection nozzle comprising a receptacle 7 is positioned at the downstream end of the body 2, the injection system being conventionally covered by an outer protection (not shown) to ensure the asepsis of the injection device 1. A pyrotechnic gas generator 70 containing a pyrotechnic charge 72 is fixed by being screwed to the upstream end of the body 2 by means of a connecting member 71 which bears on the reservoir 3, the seal being ensured by a circular O-ring. The body 2 of the injection device 1 comprises two diametrically opposite windows in order to view the liquid active principle 6 contained in the reservoir 3. Downstream of the body 2, in a suitably shaped bore, the receptacle 7, which will be described in more detail below, is shrunk on. The reservoir 3 bears on the receptacle 7 and is centered in the downstream part of the body 2, an intermediate transparent material 9 being positioned around said reservoir 3. Upstream, the body 2 receives the connecting member 71 which is centered around the end of the reservoir 3. The latter essentially consists of a glass tube closed at both ends by a movable upstream stopper 4 and a movable downstream stopper 5, these being elements conventionally used in needleless injection devices and obtained by molding elastomers compatible with the liquid active principle 6 for a long duration, for example chlorobutyl or bromobutyl whose Shore hardness is schematically set between 45 and 70. These elements may receive surface treatments, in particular to facilitate their movement in the tubular reservoir 3. At rest, each element has a diameter about 10% greater than the internal diameter of the reservoir 3 and a height schematically between 0.5 and 0.8 times this diameter. Once engaged, each element has, due to the deformations it undergoes, a height of between around 0.6 and 1.0 times the internal diameter of the reservoir 3. In this exemplary embodiment, the receptacle 7 is implemented by a part of cylindrical-conical outer shape which comprises a central cavity 10 in which the downstream stopper 5 will come to be housed. On its periphery the receptacle 7 comprises three injection ducts 8 uniformly offset in relation to each other. The diameter of the central cavity 10 is equal to that of the reservoir 3, and its free height is equal to that of the downstream stopper 5. When the latter has reached the base 7a of the receptacle 7 due to the actuation of the pyrotechnic gas generator 70, each injection duct 8 is then brought into communication with the liquid active principle 6 by means of an inlet 8a, said liquid active principle 6 flowing with a speed corresponding to the pressure transmitted by the upstream stopper 4. More precisely, the height of the cavity 10 in millimeters is chosen so as to be between a minimum height and a maximum height respectively defined by the following equations: • minimum height = 3 • maximum height = 15 x exp(-(V/9)2) +10 where V is the speed of the initial increase in the pressure profile expressed in bars per microsecond. The speed of the initial increase in pressure will be understood to involve the calculation of dP/dt throughout a period of time going schematically from 0 to 0.5 millisecond. In addition, each injection duct 8 is shaped so that the ratio of the length of said injection duct 8 to the height of the cavity 10 is between 1 and 2. According to a preferred embodiment, the height of the cavity 10 in millimeters is between a minimum height and a maximum height respectively defined by the following equations: • minimum height = 12 x exp(-(V/18)2)+4 • maximum height = 14 x exp(-(V/9)2)+9 and the ratio of the length of each injection duct 8 to the height of the cavity 10 is between 1.1 and 1.6. Even if several parameters such as the number and the diameter of the orifices in the injection ducts 8, or the quantity of liquid active principle 6, play a part in controlling the injection depth, it should be properly understood that a large variety of pressure profile shapes is available. •Indeed, with reference to figures 2 to 5, it will be noticed that just as much for a pyrotechnic charge 72 of high intensity, the pressure profile of which is shown in figure 2 and characterized by a time for an increase in pressure to 80 bar of around 0.2 millisecond, as for other pyrotechnic charges 72 of medium, low, or very low intensity, the pressure profiles of which are shown in figures 3 to 5 and which are characterized by a time for an increase in pressure to 80 bar of around 0.5 millisecond, 1.0 millisecond and 2.0 milliseconds respectively, it is possible to obtain different pressure profiles for a given intensity according to the type of primer 73 chosen to initiate the pyrotechnic charge 72. By way of illustration, in each of the configurations shown in figures 2 to 5, two examples of different pressure profile curves are plotted. The preferred pressure profile curve with the lowest final pressure is shown with a continuous line and the pressure profile curve with the highest final pressure is shown with a dotted line. It has been observed that it is possible, for example to carry out completely satisfactory subcutaneou; injections of 0.5 milliliter of liquid active principlf 6 with a pressure of around 8 0 bar at the start of the injection and of 30 bar at the end of the injection, for an injection device 1 equipped with three injection ducts 8 of 250 micrometers diameter. Of course, the pressure values and the number/diameter of the injection ducts 8 are suited to the quantity of liquid active principle 6 to be injected, along with its viscosity and the desired injection depth. In this embodiment the pyrotechnic gas generator 70 acts on the upstream stopper 4 by means of a piston 11 of effective cross section equal to that of said upstream stopper 4. Since this piston 11 is in contact with the upstream stopper 4, there is therefore no shock or ram effect at the start of operation. This piston 11, thanks to its sealing system, prevents the gases generated by the combustion of the pyrotechnic charge 72 from coming into contact with the upstream stopper 4, and therefore allows possible damage thereof and gas leakage into the liquid active principle 6 contained in the reservoir 3 to be avoided. The piston 11, of a suitable color, may also serve as an operating indicator by appearing in the viewing windows of the body 2. At this stage we will describe the main elements of the pyrotechnic gas generator 7 0 on top of the pyrotechnic charge 72 and the primer 73. More precisely, the pyrotechnic gas generator 70 comprises a connecting member 71 positioned around the piston 11, and in which the pyrotechnic charge 72 is located, just above said piston 11. The primer 73 is mounted on top of the pyrotechnic charge 72, the combustion of which is initiated when said primer 73 is struck by a striker 74. In the initial position, the striker 74 is held in a striker guide 75 screwed into the connecting member 71 by balls 77 partly engaged in a groove in the striker 74. A striking device is also provided and breaks down into a pusher 7 8 having an enlarged groove 79 and an internal spring 76. The pusher 78 slides on the outside of the striker guide 75, and it is held by lugs moving in lateral grooves. This pusher 78 constitutes in this example the triggering element. Of course, to initiate the combustion of the pyrotechnic charge 72, it is possible, without departing from the scope of the invention, to use initiation devices other than the previously described striker device. Without going into details and without seeking to be exhaustive, we mention as examples electric battery initiation devices or piezoelectric initiation devices. The pyrotechnic gas generator 70 may optionally be replaced by a gas generator, consisting of a reservoir of compressed gas closed bv a cruick openina valve. The triggering element will open said valve, and the compressed gases from the reservoir will then be able to expand and act on the pushing means. For the use of the injection device 1 according to the invention, after having removed the asepsis cap and having placed the downstream side of said injection device 1 on the skin of the subject to be treated, the operator presses with his/her thumb the pusher 78, which is pushed in, compressing the spring 76. The pusher 78 moves translationally until the enlarged groove 79 of the striker 74 reaches the height of the balls 77. On doing this, the latter balls engage under the effect of gravity in the enlarged groove 79 and thus release the striker 74 which then violently strikes the primer 73, the initiation of which ignites the pyrotechnic charge 72. The gases generated by the latter will, in a known manner, force the column consisting of the upstream stopper 4, the liquid active principle 6 and the downstream stopper 5 to slide along the reservoir 3 until the downstream stopper 5 stops against the base 7a of the receptacle 7. Under the effect of the deformation, the downstream stopper 5 frees the inlets 8a of the injection ducts 8 and therefore allows the liquid active principle 6 to be injected at high speed so as to be able to pass through the skin of the person to be treated. Although the invention has been described in connection with particular exemplary embodiments, it is obvious that it is in no way limited thereto and that it covers all the technical equivalents of the means described and their combinations if these fall within the scope of the invention. We claim: 1. A needleless injection device (1) comprising an energy source such as a gas generator, a reservoir (3) blocked by an upstream stopper (4) and a downstream stopper (5) between which a liquid active principle (6) is housed, and an injection nozzle equipped with a receptacle (7) and with at least one injection duct (8), said receptacle containing a cavity (10) with a height equal to the distance covered by the downstream stopper before opening each injection duct, characterized in that it is shaped such that: the height of the cavity in millimeters is between a minimum height and a maximum height respectively defined by the following equations: • minimum height = 3 • maximum height = 15 x exp (-(V/9)2) +10 where V is the speed of the initial increase in the pressure profile expressed in bars per microsecond; - the ratio between the length of each injection duct and the height of the cavity is between 1 and 2. 2. The injection device (1) as claimed in claim 1, characterized in that the minimum height of the cavity (10) in millimeters is defined by the following equation: • minimum height = 12 x exp (-(V/18)2)+4. 3. The injection device (1) as claimed in either of claims 1 and 2, characterized in that the maximum height of the cavity (10) in millimeters is defined by the following equation: • maximum height = 14 x exp (- (V/9)2)+9. 4. The injection device (1) as claimed in any of claims 1 to 3, characterized in that the ratio of the length of each injection duct (8) and the height of the cavity (10) is between 1.1 and 1.6. 5. The injection device (1) as claimed in any of claims to 4, characterized in that it is shaped in such a way that the time for an increase in pressure to 80 bar is between 0.2 and 2.0 milliseconds. 6. The injection device (1) as claimed in any of claims 1 to 5, characterized in that the energy source consists of a pyrotechnic gas generator (70) equipped with a pyrotechnic charge (72) and an ignition system. The present invention relates to a needleless injection device (1) comprising a reservoir (3), obturated by an upstream stopper (4) and a downstream stopper (5) between which a liquid active principle (6) is accommodated, and a receptacle (7) comprising at least one injection conduit (8), said receptacle comprising a cavity (10) whose height is equal to the distance travelled by the downstream stopper before each injection conduit is opened, - the height of the cavity in millimeters being between a minimum height and a maximum height, respectively defined by the following relationships, • minimum height = 3, • maximum height = 15 x exp. (-(V/9)2) +10, where V is the initial speed of ascent of the pressure profile expressed in bar per microsecond, - the ratio between the length of each injection conduit and the height of the cavity being between 1 and 2.

Full Text

Needleless injection device with double stopper with
low pressure profiles
The technical field of the invention is that of
prefilled, disposable needleless injection devices,
operating with an energy source such as, for example, a
gas generator and used for intradermal, subcutaneous
and intramuscular injections of a liquid active
principle for therapeutic use in human or veterinary
medicine.
The active principle consists of a more or less viscous
liquid, a liquid mix, or a gel. The active principle
may also be a solid in solution in a solvent suitable
for injection, or consist of a powdery solid suspended
at a certain concentration in an appropriate liquid.
The particle size of the active principle must
therefore be compatible with the diameter of the ducts
to avoid blocking them.
As used in the present application, the term 'liquid
active principle' constitutes the generic definition
covering all the previously mentioned embodiments of
the active principle.
Needleless injection devices comprising a reservoir of
liquid active principle already exist in tube form and
have been the subject of patents. For example, the
patent application FR 2 853 837 may be cited, which
relates to a needleless injection device comprising an
injection nozzle and a tube intended to receive a
liquid active principle to be injected, said tube being
fixed to said nozzle with the help of connecting means.
The person skilled in the art traditionally seeks to
minimize or even eliminate the risks of damaging, on
the one hand, the tube containing the liquid active
principle and, on the other hand, the downstream
stopper in the specific Mouble stopper' configuration

described, in particular, in the patent application
WO 01/58512. Said configuration is characterized by the
presence of a column of liquid delimited, on the one
hand, by the side wall of the tube and, on the other
hand, by an upstream stopper and a downstream stopper,
between which the liquid active principle is housed.
Under the effect of the gas generation, said column
moves in the tube until the downstream stopper comes
into contact with the base of a receptacle located in
the nozzle so as to free the injection ducts in order
to expel said active principle. However, when the
downstream stopper hits the base of said receptacle, it
creates a Shockwave that will propagate through to the
tube and the intensity of which is a maximum at the end
of said tube which is in contact with the nozzle. In a
'double stopper' configuration, the downstream stopper
and the glass tube are the two most stressed elements
during the operation of the needleless injection
device. The latter must consequently be shaped in such
a way that the speed of impact of the downstream
stopper in the receptacle is less than the limit speed
acceptable for the mechanical strength of the
components of said injection device. In addition, it is
known that the time separating the opening of the
injection ducts and the start of the output of the jet
from the injection ducts must be longer than the
attenuation time of the pressure oscillations generated
by the opening of the injection ducts.
In the technical literature of the field in question it
is traditionally mentioned that it is necessary to
apply, to the liquid active principle to be injected,
on the one hand a high pressure between 200 and 500 bar
in order to pierce the skin, and on the other hand a
constant or decreasing pressure through to the end of
the injection in order to ensure the transfer of the
liquid active principle, the final values generally
being between 40 and 250 bar.

However, there is a major stake in reducing the
operating pressures so as to construct strong and
economical needleless injection devices, more
particularly for single-use devices or the consumable
parts, such as the injection nozzle, of reusable
devices while guaranteeing good reproducibility of
injections.
It has been surprisingly observed that the subject of
the present invention precisely enables excellent
needleless injection results to be attained with
pressure profiles with initial values between 50 and
150 bar, preferably between 70 and 100 bar, i.e. values
clearly lower than those commonly accepted in the field
considered.
More precisely, the subject of the present invention
relates to a needleless injection device comprising an
energy source such as a gas generator, a reservoir
blocked by an upstream stopper and a downstream stopper
between which a liquid active principle is housed, and
an injection nozzle equipped with a receptacle and with
at least one injection duct, said receptacle containing
a cavity with a height equal to the distance covered by
the downstream stopper before opening each injection
duct, characterized in that it is shaped such that:
the height of the cavity in millimeters is
between a minimum height and a maximum height
respectively defined by the following equations:
• minimum height =3
• maximum height = 15 x exp(-(V/9)2)+10
where V is the speed of the initial increase in
the pressure profile expressed in bars per
microsecond;
- the ratio between the length of each injection
duct and the height of the cavity is between 1 and 2.
The speed of the initial increase in pressure will be
understood to involve the calculation of dP/dt

throughout a period of time going schematically from 0
to 0.5 millisecond.
In addition, with a needleless injection device
according to the invention it is possible to obtain
pressure profiles that are not necessarily flat or
uniformly decreasing, in contrast to what is commonly
accepted today in the literature.
Even if several parameters such as the number and the
diameter of the orifices in the injection ducts, or the
quantity of liquid active principle, play a part in
controlling the injection depth, a crucial advantage of
the invention lies in the fact that the large variety
of permitted shapes of pressure profile, depending on
the type of energy source used, ensures fine and
optimized management of the injection depth.
Moreover, another considerable advantage of a
needleless injection device according to the invention
is the fact that it has been observed that the final
pressure has no influence on performance as long as it
is greater than 20 bar, which should be compared with
the final values of 40 to 250 bar commonly accepted in
the literature.
Advantageously, the minimum height of the cavity in
millimeters is defined by the following equation:
• minimum height = 12 x exp(- (V/18)2)+4.
Again advantageously, the maximum height of the cavity
in millimeters is defined by the following equation:
• maximum height = 14 x exp(-(V/9)2)+9.
Preferably, the ratio of the length of each injection
duct and the height of the cavity is between 1.1 and
1.6.

Again preferably, the needleless injection device
according to the invention is shaped in such a way that
the time for an increase in pressure to 80 bar is
schematically between 0.2 and 2.0 milliseconds.
Advantageously, the energy source consists of a
pyrotechnic gas generator equipped with a pyrotechnic
charge and an ignition system.
The invention will be better understood with the help
of the detailed description set out below with regard
to the appended drawing in which:
figure 1 is a schematic longitudinal cross
section view of a needleless injection device according
to the invention;
- figures 2 to 5 show examples of pressure profile
curves obtained as a function of the velocity of the
energy source used.
A needleless injection device 1 according to the
invention, as shown in figure 1, comprises a body 2 in
which a reservoir 3 containing a liquid active
principle 6 is housed.
An injection nozzle comprising a receptacle 7 is
positioned at the downstream end of the body 2, the
injection system being conventionally covered by an
outer protection (not shown) to ensure the asepsis of
the injection device 1.
A pyrotechnic gas generator 70 containing a pyrotechnic
charge 72 is fixed by being screwed to the upstream end
of the body 2 by means of a connecting member 71 which
bears on the reservoir 3, the seal being ensured by a
circular O-ring.
The body 2 of the injection device 1 comprises two
diametrically opposite windows in order to view the
liquid active principle 6 contained in the reservoir 3.

Downstream of the body 2, in a suitably shaped bore,
the receptacle 7, which will be described in more
detail below, is shrunk on. The reservoir 3 bears on
the receptacle 7 and is centered in the downstream part
of the body 2, an intermediate transparent material 9
being positioned around said reservoir 3. Upstream, the
body 2 receives the connecting member 71 which is
centered around the end of the reservoir 3. The latter
essentially consists of a glass tube closed at both
ends by a movable upstream stopper 4 and a movable
downstream stopper 5, these being elements
conventionally used in needleless injection devices and
obtained by molding elastomers compatible with the
liquid active principle 6 for a long duration, for
example chlorobutyl or bromobutyl whose Shore hardness
is schematically set between 45 and 70. These elements
may receive surface treatments, in particular to
facilitate their movement in the tubular reservoir 3.
At rest, each element has a diameter about 10% greater
than the internal diameter of the reservoir 3 and a
height schematically between 0.5 and 0.8 times this
diameter. Once engaged, each element has, due to the
deformations it undergoes, a height of between around
0.6 and 1.0 times the internal diameter of the
reservoir 3.
In this exemplary embodiment, the receptacle 7 is
implemented by a part of cylindrical-conical outer
shape which comprises a central cavity 10 in which the
downstream stopper 5 will come to be housed. On its
periphery the receptacle 7 comprises three injection
ducts 8 uniformly offset in relation to each other. The
diameter of the central cavity 10 is equal to that of
the reservoir 3, and its free height is equal to that
of the downstream stopper 5. When the latter has
reached the base 7a of the receptacle 7 due to the
actuation of the pyrotechnic gas generator 70, each
injection duct 8 is then brought into communication
with the liquid active principle 6 by means of an inlet

8a, said liquid active principle 6 flowing with a speed
corresponding to the pressure transmitted by the
upstream stopper 4.
More precisely, the height of the cavity 10 in
millimeters is chosen so as to be between a minimum
height and a maximum height respectively defined by the
following equations:
• minimum height = 3
• maximum height = 15 x exp(-(V/9)2) +10
where V is the speed of the initial increase in the
pressure profile expressed in bars per microsecond. The
speed of the initial increase in pressure will be
understood to involve the calculation of dP/dt
throughout a period of time going schematically from 0
to 0.5 millisecond. In addition, each injection duct 8
is shaped so that the ratio of the length of said
injection duct 8 to the height of the cavity 10 is
between 1 and 2.
According to a preferred embodiment, the height of the
cavity 10 in millimeters is between a minimum height
and a maximum height respectively defined by the
following equations:
• minimum height = 12 x exp(-(V/18)2)+4
• maximum height = 14 x exp(-(V/9)2)+9
and the ratio of the length of each injection duct 8 to
the height of the cavity 10 is between 1.1 and 1.6.
Even if several parameters such as the number and the
diameter of the orifices in the injection ducts 8, or
the quantity of liquid active principle 6, play a part
in controlling the injection depth, it should be
properly understood that a large variety of pressure
profile shapes is available.
•Indeed, with reference to figures 2 to 5, it will be
noticed that just as much for a pyrotechnic charge 72
of high intensity, the pressure profile of which is

shown in figure 2 and characterized by a time for an
increase in pressure to 80 bar of around 0.2
millisecond, as for other pyrotechnic charges 72 of
medium, low, or very low intensity, the pressure
profiles of which are shown in figures 3 to 5 and which
are characterized by a time for an increase in pressure
to 80 bar of around 0.5 millisecond, 1.0 millisecond
and 2.0 milliseconds respectively, it is possible to
obtain different pressure profiles for a given
intensity according to the type of primer 73 chosen to
initiate the pyrotechnic charge 72. By way of
illustration, in each of the configurations shown in
figures 2 to 5, two examples of different pressure
profile curves are plotted. The preferred pressure
profile curve with the lowest final pressure is shown
with a continuous line and the pressure profile curve
with the highest final pressure is shown with a dotted
line.
It has been observed that it is possible, for example
to carry out completely satisfactory subcutaneou;
injections of 0.5 milliliter of liquid active principlf
6 with a pressure of around 8 0 bar at the start of the
injection and of 30 bar at the end of the injection,
for an injection device 1 equipped with three injection
ducts 8 of 250 micrometers diameter. Of course, the
pressure values and the number/diameter of the
injection ducts 8 are suited to the quantity of liquid
active principle 6 to be injected, along with its
viscosity and the desired injection depth.
In this embodiment the pyrotechnic gas generator 70
acts on the upstream stopper 4 by means of a piston 11
of effective cross section equal to that of said
upstream stopper 4. Since this piston 11 is in contact
with the upstream stopper 4, there is therefore no
shock or ram effect at the start of operation. This
piston 11, thanks to its sealing system, prevents the
gases generated by the combustion of the pyrotechnic

charge 72 from coming into contact with the upstream
stopper 4, and therefore allows possible damage thereof
and gas leakage into the liquid active principle 6
contained in the reservoir 3 to be avoided. The piston
11, of a suitable color, may also serve as an operating
indicator by appearing in the viewing windows of the
body 2.
At this stage we will describe the main elements of the
pyrotechnic gas generator 7 0 on top of the pyrotechnic
charge 72 and the primer 73. More precisely, the
pyrotechnic gas generator 70 comprises a connecting
member 71 positioned around the piston 11, and in which
the pyrotechnic charge 72 is located, just above said
piston 11. The primer 73 is mounted on top of the
pyrotechnic charge 72, the combustion of which is
initiated when said primer 73 is struck by a striker
74. In the initial position, the striker 74 is held in
a striker guide 75 screwed into the connecting member
71 by balls 77 partly engaged in a groove in the
striker 74. A striking device is also provided and
breaks down into a pusher 7 8 having an enlarged groove
79 and an internal spring 76. The pusher 78 slides on
the outside of the striker guide 75, and it is held by
lugs moving in lateral grooves. This pusher 78
constitutes in this example the triggering element.
Of course, to initiate the combustion of the
pyrotechnic charge 72, it is possible, without
departing from the scope of the invention, to use
initiation devices other than the previously described
striker device. Without going into details and without
seeking to be exhaustive, we mention as examples
electric battery initiation devices or piezoelectric
initiation devices.
The pyrotechnic gas generator 70 may optionally be
replaced by a gas generator, consisting of a reservoir
of compressed gas closed bv a cruick openina valve. The

triggering element will open said valve, and the
compressed gases from the reservoir will then be able
to expand and act on the pushing means.
For the use of the injection device 1 according to the
invention, after having removed the asepsis cap and
having placed the downstream side of said injection
device 1 on the skin of the subject to be treated, the
operator presses with his/her thumb the pusher 78,
which is pushed in, compressing the spring 76. The
pusher 78 moves translationally until the enlarged
groove 79 of the striker 74 reaches the height of the
balls 77. On doing this, the latter balls engage under
the effect of gravity in the enlarged groove 79 and
thus release the striker 74 which then violently
strikes the primer 73, the initiation of which ignites
the pyrotechnic charge 72. The gases generated by the
latter will, in a known manner, force the column
consisting of the upstream stopper 4, the liquid active
principle 6 and the downstream stopper 5 to slide along
the reservoir 3 until the downstream stopper 5 stops
against the base 7a of the receptacle 7. Under the
effect of the deformation, the downstream stopper 5
frees the inlets 8a of the injection ducts 8 and
therefore allows the liquid active principle 6 to be
injected at high speed so as to be able to pass through
the skin of the person to be treated.
Although the invention has been described in connection
with particular exemplary embodiments, it is obvious
that it is in no way limited thereto and that it covers
all the technical equivalents of the means described
and their combinations if these fall within the scope
of the invention.

We claim:

1. A needleless injection device (1) comprising an
energy source such as a gas generator, a reservoir (3)
blocked by an upstream stopper (4) and a downstream
stopper (5) between which a liquid active principle (6)
is housed, and an injection nozzle equipped with a
receptacle (7) and with at least one injection duct
(8), said receptacle containing a cavity (10) with a
height equal to the distance covered by the downstream
stopper before opening each injection duct,
characterized in that it is shaped such that:
the height of the cavity in millimeters is
between a minimum height and a maximum height
respectively defined by the following equations:
• minimum height = 3
• maximum height = 15 x exp (-(V/9)2) +10
where V is the speed of the initial increase in
the pressure profile expressed in bars per
microsecond;
- the ratio between the length of each injection
duct and the height of the cavity is between 1 and 2.
2. The injection device (1) as claimed in claim 1,
characterized in that the minimum height of the cavity
(10) in millimeters is defined by the following
equation:
• minimum height = 12 x exp (-(V/18)2)+4.
3. The injection device (1) as claimed in either of
claims 1 and 2, characterized in that the maximum
height of the cavity (10) in millimeters is defined by
the following equation:
• maximum height = 14 x exp (- (V/9)2)+9.
4. The injection device (1) as claimed in any of claims
1 to 3, characterized in that the ratio of the length
of each injection duct (8) and the height of the cavity
(10) is between 1.1 and 1.6.

5. The injection device (1) as claimed in any of claims
to 4, characterized in that it is shaped in such a
way that the time for an increase in pressure to 80 bar
is between 0.2 and 2.0 milliseconds.
6. The injection device (1) as claimed in any of claims
1 to 5, characterized in that the energy source
consists of a pyrotechnic gas generator (70) equipped
with a pyrotechnic charge (72) and an ignition system.

The present invention relates to a needleless injection device (1) comprising a reservoir
(3), obturated by an upstream stopper (4) and a downstream stopper (5) between which a
liquid active principle (6) is accommodated, and a receptacle (7) comprising at least one
injection conduit (8), said receptacle comprising a cavity (10) whose height is equal to
the distance travelled by the downstream stopper before each injection conduit is
opened, - the height of the cavity in millimeters being between a minimum height
and a maximum height, respectively defined by the following relationships, • minimum
height = 3, • maximum height = 15 x exp. (-(V/9)2) +10, where V is the initial speed of
ascent of the pressure profile expressed in bar per microsecond, - the ratio between the
length of each injection conduit and the height of the cavity being between 1 and 2.

Documents:

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Patent Number

278852

Indian Patent Application Number

561/KOLNP/2009

PG Journal Number

01/2017

Publication Date

06-Jan-2017

Grant Date

31-Dec-2016

Date of Filing

12-Feb-2009

Name of Patentee

CROSSJECT

Applicant Address

12 QUAI HENRI IV 75004 PARIS

Inventors:

#	Inventor's Name	Inventor's Address
1	ALEXANDRE PATRICK	14 AVENUE DE LA LIBÉRATION 70100 GRAY

PCT International Classification Number

A61M 5/30

PCT International Application Number

PCT/FR2007/001055

PCT International Filing date

2007-06-26

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	06/06506	2006-07-18	France