Reconstituting device for injectable medication

Details Reconstituting device for injectable medication Reconstituting device for injectable medication

1999-03-16

2003-11-11

Mendez, Manuel (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06645171

ABSTRACT:

The present invention relates to a device, a pack and a kit for reconstituting a liquid for medical use, such as a parenteral or pharmaceutical liquid.
It is common practice for people requiring frequent parenteral administration of drugs to be provided with home-use kits containing autoinjectors which may be used for the purposes of self-administration. Liquid formulations of drugs are however seldom stable over prolonged periods of time and it is common for the drug itself to be provided in a solid form eg. a lyophilised (i.e. freeze dried), dehydrated or crystalline form. Typically, a user might be provided with a two weeks' supply of a lyophilised drug in sealed vials together with a supply of cartridges containing diluent. However, one problem associated with conventional autoinjector devices is the lengthy procedure (in excess of 40 steps) needed to reconstitute the solid drug into a liquid formulation prior to administration.
A known drug reconstitution device is illustrated in
FIG. 1
of the accompanying drawings. In normal use, a plunger pin
1
is screwed into a plunger
2
in a cartridge
3
which contains a diluent for the drug. The cartridge
3
is placed into a barrel
4
of a dismantled autoinjector and a collar
5
is screwed onto a thread
11
thereby holding the cartridge inside the barrel
4
, with the plunger pin projecting outwardly of the barrel. A vial
7
containing a drug in solid form has a flip-off plastic seal
7
b
on a bung
7
a
. The seal
7
b
is removed and the exposed portion of the bung is sterilised with an alcohol swab. The drug vial
7
is slid into the end of an adapter
8
. A needle
10
is screwed onto a thread
6
a
of the barrel
4
and an outer needle cover
12
and an inner needle cover
13
are removed. The adapter
8
is then screwed onto a thread
6
of the barrel
4
, at which time the needle
10
penetrates the bung
7
a
of the drug vial
7
.
To effect reconstitution of the drug formulation, the complete assembly is held vertically with the needle pointing upwards and the plunger pin
1
is gently depressed thereby injecting the contents of the cartridge
3
into the vial
7
. The whole assembly is inverted and typically left to stand for 5 minutes to ensure complete dissolution of the drug. After ensuring that the plunger pin
1
is fully depressed the complete assembly is held vertically with the needle pointing upwards and the plunger pin
1
is gently pulled out thus drawing the constituted drug formulation into the cartridge. The vial adapter
8
is then unscrewed from thread
6
and discarded along with the empty vial
7
. With the needle pointing vertically upwards, the plunger pin
1
is gently depressed until a few droplets of liquid appear at the end of the needle to ensure that any air trapped within the cartridge is removed. The inner needle cover
13
and the outer needle cover
12
are replaced onto the needle prior to the needle
10
being unscrewed from thread
6
a
and discarded. The plunger pin
1
is unscrewed from the plunger
2
and the collar
5
from thread
11
and both may be discarded. The reconstitution process is now complete and the charged cartridge may be loaded into an autoinjector which may be re-assembled and primed ready for use.
Added to the problem of the lengthy reconstitution procedure, it has also been observed with devices of this type that foaming may occur when the cartridge contents are introduced to the vial. This undesirable effect is limited to a certain degree provided that the user follows the recommended procedure and holds the assembly with the needle pointing upwards before gently depressing the plunger and injecting the liquid vertically upwards into the drug vial. However the lack of control which the user is generally able to exert over the transmission of the liquid diluent onto the drug means there is still a considerable risk of foaming and associated unwanted effects, especially if the diluent is injected into the vial too rapidly. It is difficult for the user to be able reliably to control the rate at which diluent passes into the vial to avoid foaming on each occasion that the device is used.
Thus viewed from one aspect the present invention provides a device for reconstituting a liquid for medical use by bringing together a first liquid medium contained in a first vessel and a second medium contained in a second vessel, the device comprising means for supporting the first and second vessels, and a movable operating member for applying a force to cause the first liquid medium to be delivered at a controlled rate from the first vessel into the second vessel.
Since the device both supports the first and second vessels and provides a force for causing controlled delivery, this saves a user from performing these tasks and thus simplifies operation. In general, too rapid delivery can be avoided, substantially minimising effects such as foaming with certain media.
The device according to the invention is most convenient for reconstituting solid drugs (e.g. lyophilised drugs in the form of powders or pastes and the like) into a liquid solution or suspension using appropriate solvents, diluents, carriers, etc. However, the device is equally useful for contacting a first liquid (or a first mixture of liquids) with a second liquid or suspension or a mixture of liquids and/or suspensions.
Particular examples of drugs which may be provided in a lyophilised form include growth hormone, fertility drugs, antibiotics (eg. cephalosporins) and renitidine.
Although the first and second vessels may take various forms, in one preferred form of the invention the device is suitable for use with a first vessel in the form of a cartridge with a movable plunger and a second vessel in the form of a vial. The movable operating member of the device can then apply a force to move the plunger and thereby effect delivery.
The media, once brought together, are preferably transferred from the second vessel to the first vessel. It is therefore particularly convenient for the device to be reversibly operable to deliver the media back to the first vessel, e.g. a cartridge, preferably with control of the rate of delivery, although control is not essential during return delivery.
The movable operating member may be driven in various ways, including but not limited to, the use of compressed gas, one or more springs eg. a spring driven motor, or another form of motor eg. an electrically driven motor. In a preferred embodiment, a weight provides the force to effect delivery. In another preferred embodiment, a spring is used.
The rate at which the movable operating member moves will be dependent on a number of factors. In general, the movable operating member will be driven and its movement will be resisted by suitable damping means, for example frictional damping means. In seeking to eliminate unwanted effects such as foaming, it is possible to select e.g. a weight having an appropriate mass or a spring having an appropriate spring constant to provide the drive for the movable operating member and to select components with appropriate frictional interaction in order to give a degree of control over the speed at which liquid is delivered into the second vessel.
Alternative or additional forms of damping may be provided. Thus in a further embodiment of the invention compressed gas may be provided to act against the delivery force whilst being allowed to escape from the region in which it is confined (eg. by bleeding through a small vent). In one preferred embodiment, movement of the movable operating member is controlled at least partly by the flow of gas via a restricted flow path. Alternatively or additionally, there may be hydraulic damping means.
The flow path of the first liquid medium from the first to the second vessel will also tend to introduce its own resistance to flow and will thus have an effect on the rate of delivery. This can be taken into account when designing the device for use with a particular liquid flow path (which may for example be provided by a needle or the like). Account may

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