Patent Description:
Auto-injectors automate the injection stroke alleviating the need for the patient or professional to actuate the plunger rod.

<CIT> discloses an injector assembly comprising a casing within which a collapsible medicament container, a biasing means consisting of a first and a second spring for applying a first and a second pressure continuously to a piston and consequently to the container. The injector assembly according to prior art further comprises a shuttle with needles at each of its sides and a removable needle guard. Prior to use of the injector according to prior art patent application <CIT>, the needle guard has to be removed. In use, the first spring acts between second spring and the piston to apply a first force to the piston in such a way that when the first spring is compressed, it provides a biasing force between the second spring and the piston, thereby the collapsible medicament container is pushed by the piston against the needle, which perforates the septum. The injector assembly is configurated to pressurize the medicament with different viscosity under different pressure during the storage.

In an example, an auto-injector comprises in an outer casing that holds a standard cartridge comprising a barrel with a drug contents being contained by a movable plunger or stopper at one end, and a seal or septum and metal crimp or cap to hold said septum in place at the other end. A biased means that pushes against the movable plunger or stopper of the cartridge thus pressurizing the drug contents. A needle shuttle is held within casing comprises two needles that are attached and connected to each other, the first needle being the injection needle and the second needle being the septum needle. A means or shoulder retains the cartridge in its correct position when inserted and prevents it from being pushed against the needle shuttle. A needle guard is connected to the casing, being biased outwards by a spring or the like such that the needle is always covered by the needle guard, thus hiding the needle before and after the injection.

The auto-injector according the present invention may further comprise a needle guard locking mechanism that prevents the needle guard from being pushed back a second time, thus preventing needle stick injuries after use.

The auto-injector may further comprise an indicator. The indicator may be in form of an indicator rod that is attached to the biased means or the movable plunger or stopper and thus moves with it, thus allowing to indicate the progress of the injection progress. The indicator rod may be connected and used to operate any other indicator such as a rotary indicator or an electronic indicator or a connectivity device.

In one embodiment, the indicator extends beyond the rear casing to a distance determined by the fill volume and enabling the user to monitor the status of the injection.

In a preferred embodiment, the indicator rod has a closed end and contains the spring within. The outer casing comprises a portion that allows to monitor the progress and status of the injection progress, for example a cap which is transparent or has viewing windows. If the drug volume is fully injected, the indicator is no longer visible indicating end of injection. Placing the spring inside the indicator has the advantage that the spring can be longer than if the indicator is placed inside the spring or the device may be shorter. A longer spring means a higher mean force which is advantageous for viscous drugs.

The invention further relates to a modular designed auto injector which is composed of several sub-assemblies or modules. For ease of assembly, the modular auto-injector comprises three sub-assemblies, namely a cartridge, a power source and indicator sub-assembly and a needle and needle guard sub-assembly.

The cartridge sub- assembly comprises a barrel, a drug volume that is bounded by a plunger and a crimped septum.

The power source and indicator assembly comprises a biased means or spring and an indicator rod that is held within a rear casing. The invention allows for the cartridge to have a variable fill volume when assembled with the power source and indicator sub-assembly.

In order to indicate the status and progress of the injection process, the indicator rod may be connected to either the biased means or spring or to the movable plunger or stopper upon assembly of the device in a way that it moves with it.

If the biased means is a spring it may further comprise a spring locking member. In this case the power source and indicator assembly may further comprise a second weaker spring to pressurize the cartridge drug contents prior to injection while the first spring is locked by the spring locking member. The second spring also avoids a pressure pulse when the second spring is released.

The needle and needle guard sub-assembly comprises a front casing holding a needle shuttle with an injection needle and a septum needle, the shuttle being held within the casing , a needle guard for preventing needle stick injuries that is biased outwards by a spring, a locking mechanism that prevents the needle guard from being pushed back a second time, and a means to retain the cartridge in its correct position when inserted.

The injection needle and the septum needle may have the same diameter or gauge or have different diameters or gauges. They may have the same type of bevel tip or different types of bevel tip. For example, to minimize injection time the septum needle may be of larger diameter or smaller gauge than the injection needle. For simplicity a single needle may be used with two sharp ends or bevels. Different needle gauges and/or bevels can be used to ensure the injection needle penetrates the injection site before the septum needle penetrates the septum to ensure a full injection. The interchange of the injection needle allowing adaption for subcutaneous, intramuscular or intra-dermal injection.

The modular auto-injector may be assembled by an easy two-step process such as placing the cartridge into the needle and needle guard sub-assembly followed by connecting it with the power source and indicator sub-assembly in a way that the drug contents in the cartridge are pressurized. If the device is intended for single use, any connection means to lock the sub-assemblies of the modular auto-injector together may be used, such as a snap fit.

In a preferred embodiment, the modular auto-injector can be re-assembled or is multiple use. In this case the needle and needle guard assembly and the power source and indicator assembly may be connected by a a bayonet fit or a screw or are hinged together to allow a reversible connection. In addition, the biased means of the power source and indicator assembly allows for a multiple use such as an electric motor, a liquified gas cannister or a spring with means to re-compress the spring. Finally, the needle and needle guard assembly comprises a seal and a removable needle cap that always keep the needles and the cartridge septum sterile.

The embodiments of the auto-injector according to the present invention may be assembled under sterile conditions or may be submitted to terminally sterilization after assembly.

If the drug in the cartridge is a small molecule (non-biologic) the assembled device may be terminally sterilized in a blister or pouch using gas, vapor or radiation such as gamma ray, e-beam or any other.

When sterilizing the device with sensitive drug contents such as biologic drugs, the blister/pouch with the assembled device has at least a portion made from gas permeable material. The device may have gas pathways to assure that the needles and the external surface of the cartridge septum are sterilized. The device can then be placed in a gaseous environment such as ethylene oxide or nitrogen dioxide for sterilization.

To prevent the gas affecting sensitive drug contents, the cartridge assembly may preferably have gas impermeable components, in particular plunger/stopper and septum/cap. The gas used should preferably not be at elevated temperatures and preferably below body temperature and preferably below <NUM>.

The device may be supplied as a ready-to-use medical device or supplied pre-assembled as a combination product ("kit") for self-assembly by the user.

Sterilisation may take place before assembly or after assembly in which case it is terminally sterilized. If sterilized before assembly only the needle and guard sub-assembly or module <NUM> need be sterilized. The assembled device may be terminally sterilized in a blister or pouch. A needle cap and maybe a seal is required if the device is sterilized outside a blister. If the device is assembled by the user, the cartridge can be supplied in a blister or with no blister in which case the septum needs to be wiped with ethanol before device assembly.

Table <NUM> shows an overview of the different options as regards sterilization, options <NUM> to <NUM> allowing for re-assembly.

The auto-injector according to the present invention may be used with drug suspensions or solutions and API's or biologics. If the suspension is unstable with settling tendencies the cartridge needs to be shaken before use to re-mix.

The modular design has the advantage that each sub-assembly may be produced separately under conditions individually adapted. It further allows for flexibility in production and allows different auto injectors to share modules. The modular design also allows for part exchangeability which bears the additional advantage is that modules or sub-assemblies can be interchanged to change the characteristics of the auto-injector. For instance, by changing the needle and hub and needle guard assembly the device can be changed from a subcutaneous auto-injector to an intramuscular or intra-dermal auto-injector. It also allows for the power source module to be a reusable device. The modular designed auto-injector does also allow the cartridge to be exchanged, either after it has been used or if its shelf-life has expired.

The present invention allows for the use of industry standard injection cartridge and manufacture auto-injectors with a dry needle during storage and with various other advantages.

With reference to the figures, specific embodiments of the present invention are described hereinafter:
<FIG> shows an auto injector <NUM> according to the present invention. A standard cartridge <NUM> has barrel <NUM> with drug solution or suspension <NUM> within contained by a movable plunger or stopper <NUM> at one end and a rubber seal or septum and metal crimp <NUM> at the other end. The cartridge <NUM> is held in casing <NUM>. A biased means <NUM> pushes against the stopper <NUM> pressurizing contents <NUM>. A needle shuttle <NUM> is held within casing <NUM>. Shuttle <NUM> has two needles <NUM> and <NUM> attached and connected to each other. Needle <NUM> is the injection needle and needle <NUM> is the septum needle. A means <NUM> retains cartridge <NUM> in its correct position when inserted and prevents it from being pushed against the shuttle. A needle guard <NUM> and spring <NUM> are held to casing <NUM>. Needle guard <NUM> has the purpose of preventing needle stick injuries after injection.

<FIG> shows the auto injector <NUM> with an indicator rod <NUM> being attached to stopper <NUM>.

<FIG> and <FIG> show the auto-injector <NUM> during injection. Auto-injector <NUM> is pressed against injection site <NUM>. Needle <NUM> is inside the injection site <NUM> and delivering drug solution or suspension 107a as a bolus. Needle guard <NUM> has been pushed against injection site <NUM> and been pushed back relative to casing <NUM> against spring <NUM> pushing back shuttle <NUM>. Needle <NUM> has pierced septum <NUM> and the pressurized contents <NUM> is flowing into injection site <NUM> via needles <NUM> and <NUM> and delivering a bolus 107a. The indicator <NUM> is moving forward showing injection progress. To ensure a complete injection, the injection needle penetrates the injection site (<FIG>) before the septum needle penetrates the septum (<FIG>).

In <FIG> the auto injector <NUM> has finished injecting, the needle guard <NUM> has been pushed back by spring <NUM> and been locked into position by locking mechanism <NUM>.

<FIG> shows a modular auto injector according to the present invention which is made up by three sub-assemblies: A cartridge sub-assembly <NUM>, a needle and needle guard sub-assembly <NUM> and a power source and indicator sub-assembly <NUM>.

Cartridge sub-assembly <NUM> has a cartridge <NUM> with barrel <NUM>, drug volume <NUM> held by plunger <NUM> and septum <NUM>.

Power source and indicator sub-assembly <NUM> has a biased means or spring <NUM> and indicator rod <NUM> held within casing 110a.

Needle and needle guard sub-assembly <NUM> has a casing 110b holding a needle shuttle <NUM> with needles <NUM> and <NUM>. A needle guard <NUM> for preventing needle stick injuries is biased outwards by spring <NUM>. Module <NUM> may be supplied sterilized. It also has a guard locking mechanism a shoulder <NUM> that retains the cartridge <NUM> in its correct position when inserted not shown.

Module <NUM> may contain a needle for subcutaneous, intramuscular or intra-dermal injections.

<FIG> shows a <NUM>-dimensional view of the modular auto injector. Cartridge <NUM> is placed into sub-assembly <NUM> followed by sub-assemblies <NUM> and <NUM> being locked together in the directions of arrows <NUM> and <NUM> pressurizing the drug contents in cartridge <NUM>.

The assembled auto injector <NUM> is shown with an additional indicator cap and indicator knob 111a which is attached to the indicator rod <NUM> (not shown) and an additional front cap <NUM> which are optional features.

In <FIG> sub-assembly 183a has a locking member <NUM> holding spring <NUM> compressed and back by the indicator rod <NUM> for ease of device assembly. The locking member <NUM> is slowly removed after assembly of the device freeing spring <NUM> to slowly compress cartridge contents and avoid a pressure pulse. The locking member <NUM> may be a nut on a threaded indicator rod or any other mechanism.

In <FIG> sub-assembly 183b has an additional spring 112b which is weaker than spring <NUM> that compresses the drug solution in the cartridge after the device is assembled. Before injecting the locking device <NUM> is removed so that spring <NUM> can fully pressurize the cartridge contents.

In <FIG> another embodiment is shown. A latch <NUM> holds the spring <NUM> compressed and holds it back for easy assembly. Latch <NUM> releases the spring when the device is assembled by outwards axial movement of the indicator <NUM> compressing the drug contents.

<FIG> shows another embodiment of the invention. Module <NUM> is a combination of sub-assemblies <NUM> and <NUM> and has the cartridge <NUM> supplied to the user with the needles <NUM> and <NUM> attached and is held in place with the needles <NUM> and <NUM>.

<FIG> shows an assembled and ready-to-use auto-injector that is being placed in a blister or pouch <NUM> and submitted to a gaseous environment for terminal sterilization, <NUM> indicates the sterilized area.

<FIG> shows an assembled and ready-to-use auto-injector wherein the indicator <NUM> contains the spring <NUM> within and an cap <NUM> that allows the observation of the injection progress.

<FIG> shows an assembled and ready-to-use auto-injector comprising an additional seal <NUM> and a elastomeric needle cap <NUM> to keep the needles sterile. The use of cap <NUM> and optionally seal <NUM> allows for terminal sterilization without the use of a blister. For easier removal from needle guard <NUM> the cap <NUM> is made from an elastomeric material such as rubber.

A preferred embodiment of the present invention is a ready-to-use modular auto-injector that comprises.

Claim 1:
An auto-injector (<NUM>) comprising an outer casing (<NUM>) holding a standard cartridge (<NUM>) consisting of
a barrel (<NUM>) with a drug content (<NUM>) being contained by a movable plunger (<NUM>) at one end and a seal and metal crimp (<NUM>) at the other end,
a biased means (<NUM>) that pushes against the movable plunger (<NUM>) of the cartridge (<NUM>) pressurizing the drug content (<NUM>),
a needle shuttle (<NUM>) being held within the casing (<NUM>) comprising two needles (<NUM>, <NUM>) that are attached and connected to each other,
a first needle (<NUM>) being the injection needle and a second needle (<NUM>) being the septum needle,
a means (<NUM>) to retain the cartridge in its correct position when inserted,
characterized in that the auto-injector further comprises
a needle guard (<NUM>) and a spring (<NUM>) held to the outer casing (<NUM>), wherein the needle guard (<NUM>) is being biased outwards by the spring (<NUM>), and wherein the needle guard is configured such that during injection, when the auto-injector (<NUM>) is pressed against an injection site (<NUM>), the needle guard (<NUM>) is pushed against the injection site (<NUM>), the needle guard (<NUM>) is pushed back relative to the casing (<NUM>) against the spring (<NUM>) and thereby pushes back the needle shuttle (<NUM>) to pierce the seal and when the auto injector (<NUM>) has finished injecting, the needle guard (<NUM>) is pushed back by spring (<NUM>) such that the first needle (<NUM>) is always covered by the needle guard (<NUM>).