A fluid delivery device includes an automatic needle retraction mechanism configured to automatically retract a delivery end of a needle into a housing. In one embodiment, the needle assembly is configured to automatically withdraw the delivery end of the needle into the housing upon an actuator moving from the first position to the second position. In one embodiment, the needle assembly is configured to automatically withdraw the delivery end of the needle into the housing upon decoupling a bottom surface of the housing from a skin surface.

A segmented piston rod for an injection device includes multiple segments joined together via a hinge located on one side of each segment. The piston rod can be bent in one direction by articulating subsequent hinges while an axial force can be transmitted by the segmented piston rod to the stopper when the subsequent hinges are closed and the segments abut each other opposite to the one side of the hinge. The segmented piston rod is secured against rotation relative to the housing around the longitudinal axis of the segmented piston rod. The segmented piston rod has a last element which abuts the stopper in the reservoir and a first segment which is opposite to the last segment. The first segment is includes an internal thread matching an external thread of a drive sleeve and rotation of the drive sleeve advances the piston rod towards the stopper of the reservoir.

An automatic mixing device, an actuating device removably mounted to the automatic mixing device and a retractable syringe having the automatic mixing device are provided. The actuating device has an initially compressed spring and a trigger member that initiates spring decompression to drive depression of a mixing plunger of the automatic mixing device. A seal located in the outer chamber is capable of axial movement upon depression of the mixing plunger, from a first position in sealing engagement with one or more apertures in an inner barrel to a second position intermediate the apertures and vents in an outer barrel. This allows depression of the mixing plunger to force a first substance from the outer chamber through the apertures to mix with a second substance in an inner chamber of the inner barrel. The mixed substance in the inner barrel is then delivered by the syringe with subsequent needle retraction.

In some embodiments, a delivery device includes a device actuator and a cannula portion through which a therapeutic substance is ejected. The cannula portion includes an outer shaft, a needle that is configured to move through the outer shaft, and a plunger that is configured to move through the needle, forming a positive displacement arrangement.

A skin sensing system for a drug delivery device includes a control unit and a skin sensor comprising one or more electrodes. The skin sensor may be configured to store a threshold value associated with skin sensing, receive one or more sensed signal values .sup..from the one or more electrodes, compare the one or more sensed signal values with the threshold value, and based on the comparison, transmit a resultant signal to the control unit, The resultant signal is used by the control unit to determine whether a skin surface of a user is substantially proximate to the skin sensor upon receiving the resultant signal. A drug delivery device for sensing contact with the skin includes the skin sensing system. When the skin sensor senses that the drug delivery device is in contact with a patient's skin surface, drug delivery from the device may he permitted.

A syringe assembly includes a plunger assembly, a syringe body, and a needle. The plunger assembly includes a plunger rod, a spring, a plunger base, and a plunger plug. The plunger rod includes a first end member having a first stepped part positioned in an inner wall thereof, a second end member, and a first accommodating room. The plunger base includes a plunger body, a projection, a second stepped part, a plunger member, and a locating member. The plunger body is received in the first accommodating room, and the projection abuts against the first end member. The spring is arranged around the plunger body and positioned between the first stepped part and the second stepped part. The plunger plug is mounted to the second end member, and defines a fixing groove. The syringe body includes a needle cannula, a needle base, a fixing pole, and a fixing valve. The plunger assembly is received in the needle cannula. The needle base is mounted to the needle cannula. The fixing valve is received in the needle base. The fixing pole is received in the fixing valve and protrudes out of the needle base. The needle is received in the fixing pole. The syringe assembly of the present invention is prevented from reuse and accidently damage because the needle can retract into the plunger rod using restoring force of the spring.

An auto-injector operable in a single activation step. The auto-injector is automatically armed when removed from its carrying receptacle. The auto-injector may be prefilled with more than one constituent of a beneficial agent, stored in separated compartments, in such an arrangement that the compartments will automatically merge when the auto-injector is removed from its carrying receptacle.

A plunger, a needle assembly and a retractable syringe comprising same are provided. The plunger comprises a plunger member and a plunger outer having a lock spring that prevents or impedes movement of the plunger member after needle retraction. The plunger further comprises another locking member for engaging the barrel to prevent or impede further movement of the plunger outer after delivery of fluid contents. The plunger member has a plunger seal which engages a retractable needle of the needle assembly for retraction. The retractable needle comprises a cannula and needle body with a plurality of fluid channels that co-operate with a fluid conduit of the plunger seal to efficiently direct fluid to the cannula. A needle retainer comprises a plurality of barbed arms releasably coupled to the needle body, whereby an ejector with tabs facilitates release of the retractable needle from the needle retainer to allow compressed spring-driven retraction.

A pneumatically activated retractable-needle syringe comprising a syringe barrel, a plunger, a needle, a needle hub, a locking tip, a propellant gas release cell and a rupture mechanism is provided. The plunger is slidably disposed within and sealingly engaged with the syringe barrel, the plunger having a retraction lumen defined for receiving a needle when the retractable-needle syringe is actuated. The needle is coupled to a distal end of the syringe barrel and in fluid communication with a medicament chamber defined within the syringe barrel distally of the plunger. The needle hub is for securing the needle at the distal end of the syringe barrel, the needle hub being initially secured within a false wall against a loading force or an injection force applied by a user, and releasable from the false wall in response to a post-injection force applied by a user. The locking tip is provided at a distal end of the plunger, the locking tip being in sealing engagement with and initially secured within the retraction lumen against a loading force or an injection force applied by a user, and releasable for sliding retraction within the plunger lumen in response to release of propellant upon a post-injection force applied by a user, the locking tip being engageable with the needle hub in response to the post-injection force to provide a retraction assembly comprising the locking tip, the needle header, and the needle. The propellant release cell is positioned distally of the needle hub and contains a propellant. The rupture mechanism is positioned to puncture the propellant release cell in response to the application of the post-injection force by a user to thereby drive retraction of the retraction assembly within the retraction lumen.

An apparatus includes a container, a needle, and an actuation assembly. The container contains a dose of a naloxone composition having a delivered volume of at least about 0.34 mL. The actuation assembly includes an energy storage member that produces a force on a movable member to move the needle and to deliver the dose of the naloxone composition. The 90% confidence interval of at least one of the relative mean maximum naloxone plasma concentration after dose delivery into the body (C.sub.max), time to reach the maximum naloxone plasma concentration (T.sub.max), area under the plasma concentration-time curve from pre-dose (time 0) extrapolated to infinity (AUC.sub.0-∞), or area under the plasma concentration-time curve from pre-dose (time 0) to the time of the last quantifiable concentration (T.sub.last) (AUC.sub.0-t) of the delivered dose to a delivered dose of a corresponding naloxone composition delivered via a manually-actuated syringe is within 80% to 125%.