U.S. patent application number 09/728662 was filed with the patent office on 2001-05-31 for needleless injector drug capsule and filling method.
This patent application is currently assigned to Weston Medical Limited. Invention is credited to Weston, Terence Edward.
Application Number | 20010002433 09/728662 |
Document ID | / |
Family ID | 10785542 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010002433 |
Kind Code |
A1 |
Weston, Terence Edward |
May 31, 2001 |
Needleless injector drug capsule and filling method
Abstract
A needleless injector capsule for a liquid medicament has a
filling adapter removably, and preferably frangibly, attached
thereto. The capsule has a chamber for receiving injectate, the
chamber being provided with an injection orifice, and having a
piston located for movement therein. The adapter has a bore which
communicates with the capsule chamber via the injection orifice.
The capsule is filled by introducing injectate into the capsule
chamber through the injection orifice and excess injectate into the
bore of the adapter, and closing the bore of the adapter to the
exterior by a sealing means, leaving the bore partly filled with
excess injectate.
Inventors: |
Weston, Terence Edward;
(Eye, GB) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
Weston Medical Limited
|
Family ID: |
10785542 |
Appl. No.: |
09/728662 |
Filed: |
December 1, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09728662 |
Dec 1, 2000 |
|
|
|
09091320 |
Aug 5, 1998 |
|
|
|
Current U.S.
Class: |
604/72 ;
604/411 |
Current CPC
Class: |
A61M 5/30 20130101; A61M
5/1782 20130101; A61M 2209/045 20130101; A61M 2005/312 20130101;
A61M 2207/00 20130101; A61J 1/2096 20130101; A61J 1/2044 20150501;
A61M 2005/3118 20130101 |
Class at
Publication: |
604/72 ;
604/411 |
International
Class: |
A61M 005/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 1995 |
GB |
9525757.2 |
Dec 9, 1996 |
GB |
PCT/GB96/03017 |
Claims
1. A needleless injector capsule in combination with an adaptor
used in filling the capsule, the capsule defining a chamber which
has injectate therein and is provided with an injection orifice, a
piston being located for movement within the chamber, the adapter
being removably connected to the capsule and having a bore which
communicates with the capsule chamber via the injection orifice and
is partly filled with excess injectate, the bore being closed to
the exterior by a sealing means.
2. A combination according to claim 1, wherein the adaptor is
frangibly connected to the capsule.
3. A combination according to claim 1, wherein the adaptor is
connected to the capsule by a snap-fit connection which does not
permit reconnection after removal of the adaptor and capsule from
one another.
4. A combination according to claim 1, 2 or 3, wherein the capsule
and/or adaptor is of glass.
5. A combination according to any preceding claim, wherein the
capsule and/or adaptor is of a plastics material.
6. A combination according to claim 1, 2 or 3, wherein the capsule
and/or adaptor is made of more than one material.
7. A combination according to claim 6, wherein the capsule and/or
adaptor is internally lined with a plastics material which is
compatible with the injectate.
8. A combination according to any preceding claim, wherein the
sealing means is a sealing cap.
9. A combination according to any one of claims 1 to 7, wherein the
sealing means is a plug received within the said bore.
10. A combination according to any one of claims 1 to 7, wherein
the sealing means is constituted by portions of the adaptor which
have been sealed to one another after filling of the capsule.
11. A method of filling a needleless injector capsule with
injectate, the capsule defining a chamber which is for receiving
injectate and is provided with an injection orifice, a piston being
located for movement within the chamber, the adapter being
removably connected to the capsule and having a bore which
communicates with the capsule chamber via the injection orifice,
the method comprising the steps of: (a) introducing injectate into
the capsule chamber through the injection orifice and excess
injectate into bore of the adaptor; and (b) closing the bore of the
adaptor to the exterior by a sealing means, leaving the bore partly
filled with excess injectate.
12. A method according to claim 11, wherein step (a) is effected by
an injectate dispenser which sealingly engages with the internal
wall of the bore of the adaptor.
13. A method according to claim 11 or 12, wherein the sealing means
is a sealing cap.
14. A method according to claim 11 or 12, wherein the sealing means
is a plug received within the said bore.
15. A method according to any one of claims 11 to 14, wherein air
is evacuated from the capsule through the injection orifice prior
to step (a).
16. A needleless injector capsule in combination with an adaptor
for use in filling the capsule, the capsule defining a chamber
which is for receiving injectate and is provided with an injection
orifice, a piston being located for movement within the chamber,
the adaptor being removably connected to the capsule and having a
bore which communicates with the capsule chamber via the injection
orifice, the adaptor bore having a first portion of smaller
cross-section adjacent the injection orifice and a second portion
of larger cross-section remote from the said orifice.
17. A combination according to claim 16, wherein the adaptor is
frangibly connected to the capsule.
18. A combination according to claim 16, wherein the adaptor is
connected to the capsule by a snap-fit connection which does not
permit reconnection after removal of the adaptor and capsule from
one another.
19. A combination according to claim 16, 17 or 18, wherein the
capsule and/or adaptor is of glass.
20. A combination according to any one of claims 16 to 19, wherein
the capsule and/or adaptor is of a plastics material.
21. A combination according to any one of claims 16 to 18, wherein
the capsule and/or adaptor is made of more than one material.
22. A combination according to claim 21, wherein the capsule and/or
adaptor is internally lined with a plastics material which is
compatible with the injectate.
Description
[0001] The invention relates to a disposable needleless injector
and to a method for filling the same.
[0002] Needleless injectors are used as an alternative to
hypodermic syringes to inject drugs and medicaments through a
patient's skin into the underlying tissue. A typical injector
comprises a high pressure piston pump which dispenses the drug
through a small hole with sufficient force to pierce the epidermis
and diffuse into the tissues. The present invention is directed to
the filling of capsules for use in such injectors.
[0003] Axiomatic to the storage of the drug in the capsule is that
the filling procedure is compatible with the equipment and
protocols established within the pharmaceutical industry, and a
number of otherwise promising ideas have failed to become
commercialised because this requirement was overlooked. None of the
prior art capsules have all of the features necessary for optimum
storage of the drug and compatibility with filling machines.
[0004] The stringent requirements for ensuring optimum sterility
and quality control of drug packaging means that there is a trend
towards pre-filling the drug capsule. However, a prefilled capsule
must be able to withstand thermal expansion and contraction due to
ambient temperature fluctuations. The possible results of the
latter is that increased and unacceptable outgassing of the drug
could occur, or the drug could expand and leak past the seals.
[0005] According to the present invention there is provided a
needleless injector capsule in combination with an adaptor used in
filling the capsule, the capsule defining a chamber which has
injectate therein and is provided with an injection orifice, a
piston being located for movement within the chamber, the adapter
being removably connected to the capsule and having a bore which
communicates with the capsule chamber via the injection orifice and
is partly filled with excess injectate, the bore being closed to
the exterior by a sealing means.
[0006] According to another aspect of the invention there is
provided a method of filling a needleless injector capsule with
injectate, the capsule defining a chamber which is for receiving
injectate and is provided with an injection orifice, a piston being
located for movement within the chamber, the adapter being
removably connected to the capsule and having a bore which
communicates with the capsule chamber via the injection orifice,
the method comprising the steps of:
[0007] (a) introducing injectate into the capsule chamber through
the injection orifice and excess injectate into bore of the
adaptor; and
[0008] (b) closing the bore of the adaptor to the exterior by a
sealing means, leaving the bore partly filled with excess
injectate.
[0009] It is necessary that the pressure induced in the drug
increases very rapidly at the start of the injection, so that the
liquid effectively strikes the skin to pierce it. (Conversely, if
the pressure rise is too slow, the skin moves away from the jet
causing the jet to splash sideways without penetration). It follows
therefore that the "hydraulic circuit"--i.e. the drug capsule, its
method of attachment, and the piston should be relatively rigid,
otherwise much of the input energy at the start of the injection
will be wasted in distorting these components. Less obvious is that
any trapped air in the liquid drug will be compressed during the
injection and thus absorb energy. Of course, a small quantity of
entrapped air is permissible and almost inevitable, because unless
rigorous de-gassing of the drug is carried out before filling, very
small bubbles of air will come out of solution and coalesce within
the injectate.
[0010] In a preferred form of the above method air is evacuated
through the injection orifice before injectate is introduced into
the capsule chamber and adaptor bore.
[0011] The invention also provides a needleless injector capsule in
combination with an adaptor for use in filling the capsule, the
capsule defining a chamber which is for receiving injectate and is
provided with an injection orifice, a piston being located for
movement within the chamber, the adaptor being removably connected
to the capsule and having a bore which communicates with the
capsule chamber via the injection orifice, the adaptor bore having
a first portion of smaller cross-section adjacent the injection
orifice and a second portion of larger cross-section remote from
the said orifice. Such a construction is particularly suitable for
carrying out the above filling method including evacuation of
air.
[0012] The capsule is preferably connected frangibly to the filling
adaptor, which also serves as a reservoir to accommodate expansion
and contraction of the injectate. Immediately prior to use the
filling adaptor is broken off the capsule to expose the injection
orifice.
[0013] The invention is further described below with reference to
the accompanying drawings which show preferred embodiments and in
which:
[0014] FIG. 1 is a centre-line axial section view of a capsule
before filling;
[0015] FIG. 2 shows a filling head applying a vacuum;
[0016] FIG. 3 shows the capsule being filled;
[0017] FIG. 4 shows the filled capsule with a seal attached;
[0018] FIG. 5 shows the filling adaptor being broken off prior to
causing an injection;
[0019] FIG. 6 is an alternative sealing method.
[0020] FIG. 1 shows a capsule 1 in the form of a cylindrical
elongate tube having a means of attachment 10 at a first end, and
an injection orifice 5 at a second end. A piston 3 is slidingly and
sealingly assembled into the capsule 1 and proximal to the
injection orifice 5. The fit of the piston 3 in the capsule 1
should minimise the dead volume of air 14. A filling tube 2 has a
frangible attachment 4 to the capsule 1. Tube 2 has a cylindrical
bore 9 which is then reduced in diameter to form a capillary 15.
Capillary 15 is connected to orifice 5 of capsule 1.
[0021] Referring to FIG. 2, a filling head 18 comprising vacuum
connector 16 and injectate dispenser 7, is applied to filling tube
2. The vacuum connector 16 seals a rim 11 of filling tube 2, and
the air contained within the cylindrical bore 9, capillary 15 and
dead space 14 is evacuated. Evacuation down to 100 mbars is
adequate; a lower vacuum would take longer to achieve than would
normally be acceptable, and result in a very slow filling
procedure. Whilst maintaining the vacuum, injectate dispenser 7 is
inserted into the cylindrical bore 9, and a seal 8 on the exterior
of the dispenser 7 seals with the wall of bore 9, as shown in FIG.
3. After insertion of injectate dispenser 7, the vacuum may be
terminated, and the injectate 6 is pressurized to flow through
cylindrical bore 9, capillary 15 and injection orifice 5 and into
the capsule 1, so as to force the piston 3 towards the first end of
capsule 1 to a predetermined position. On attaining this position,
the flow of injectate 6 is stopped, and the filling head 18 removed
from filling tube 2. The capsule is now filled, and may be sealed
by a sealing cap 12, as shown in FIG. 4, or a plug 20 as shown in
FIG. 6. During filling, it is important that the injectate
dispenser 7 is inserted only part way into cylindrical bore 9, so
that a small excess 22 of the injectate remains, and after removal
of the injectate dispenser 7, an air space 21 remains.
[0022] Finally, as shown in FIG. 5, the filled capsule is assembled
to an actuator 19. To prepare the injector, the filling tube 2 is
snapped off from the capsule 1 at the frangible joint 4, together
with the sealing cap 12 and excess injectate 22. This exposes the
injection orifice 5, which is then placed on the patient's skin,
and the injection performed in the usual manner. Thus it may be
seen that the injectate is free to expand or contract during
storage (i.e. between the steps of FIGS. 4 and 5) without the risk
of leakage or excessive out-gassing. The dimension of the capillary
bore 15 should be chosen to accommodate the maximum volumetric
change through temperature variation, and also to suit the surface
tension of the injectate, so that inverting the capsule does not
result in migration of the injectate into the filling tube 2.
However, the volume of the excess injectate 22 is not critical, and
therefore the performance tolerances imposed on the filling machine
are not exacting.
[0023] The materials for constructing the capsule 1 and filling
tube 2 may be plastic or glass, and preferably transparent to
permit examination of the contents. The piston 3 may be of PTFE or
similar fluoropolymer or a low density polyethylene, for example.
Attention is directed to our published PCT application WO 95/03844
for further details of materials which can be used for the piston.
The seal 12 or 20 may be of chlorobutyl rubber or other
drug-compatible seal material. An alternative to sealing the tube 2
with cap 12 or plug 20 is to thermally reform and close the opening
to form a gas-tight welded seal. With some plastics, welding is
difficult, and the inside surface of the tube 2 may be coated with
a more suitable seal material. Again, where it is necessary to use
a particular plastic in contact with the drug, for compatibility
therewith, this could be a lining within a capsule, and/or filling
tube, made of a plastic having the required strength and durability
properties. This may be a separately made part which is then
assembled to the casing, or a co-injected moulding. Even more
layers of different plastic or other materials may be used to add
specific properties. The frangible connection 4 may be a very thin
section of material, and/or be specially treated to reduce the
strength in that area to facilitate fracture of the said
connection. Alternatively, the filling tube 2 may be an air tight
snap fit onto the capsule 1, and preferably not be re-attachable,
so as to provide tamper evidence.
* * * * *