Medication dispensing device

A medication dispensing device, comprising:

• a cartridge for containing and sealing an injectable product therein, said cartridge including a plunger therein;
• and
• injector means attached to said cartridge for delivering a desired dosage of product into a patient, said injector means including knob means for engagement by a user and a rod coupled to said knob means, said rod being axially advanceable with respect to said housing upon rotation of said knob means in a first direction, wherein said rod is advanceable a first distance to establish a set dosage of injectable product to be delivered without effecting delivery of the injectable product, clutch means in engagement with said rod for restricting rotation of said rod in a second and opposite direction;
• and a clutch disengaging means for selectively disengaging said clutch means, thereby permitting rotation of said knob means in said second direction while said cartridge is attached to said injector means to cause said rod to move axially toward said injector means to reduce the first distance of axial advancement of said rod thereby reducing the set dosage of injectable product to be delivered, wherein said rod is axially advanceable a second distance upon axial force being applied to said knob means to engage and axially advance said plunger to effect delivery of the set dosage of injectable product.

An injector device for injecting a product contained in a cartridge attached to the injector, said cartridge including a plunger therein, comprising:

• a housing;
• a drive mechanism disposed in said housing and including a dosage device having a control knob and a rod coupled to said dosage device such that upon rotation of said knob, said rod is axially advanceable a first distance to establish a set dosage of injectable product to be delivered without effecting delivery of the injectable product;
• a clutch mechanism disposed in said housing and comprising a rotatable piece that is connected to said dosage device for rotation therewith and a locking seat in engagement with said rotatable piece and being configured to restrict rotation of said rotatable piece, and hence said dosage knob, to a first direction only while the injector is attached to a cartridge;
• and
• a disengaging mechanism for selectively disengaging said locking seat from said rotatable piece thereby permitting rotation of said dosage device in a second and opposite direction while the injector is attached to the cartridge to permit an overdose measurement to be dialed back to a desired dosage, wherein said rod is axially advanceable a second distance upon axial force being applied to said knob to engage and axially advance said plunger to effect delivery of the set dosage of injectable product.

In a medication dispensing device for measuring and injecting a desired dosage of injectable product into a patient, a method for reducing an excess dosage of measured product, the method comprising the steps of:

• attaching a cartridge containing an injectable product therein to an injector including a dosage knob and an axially advanceable rod;
• rotating the knob in a first direction only to cause the rod to axially advance into the cartridge a first distance to establish a set dosage of injectable product to be delivered without effecting delivery of the injectable product;
• engaging a clutch-deactuating mechanism;
• rotating the dosage knob in a second and opposite direction until the rod has been axially retracted within the cartridge a sufficient distance to reduce the set dosage to be injected;
• and
• releasing the clutch-deactuating mechanism thereby preventing rotation of the dosage knob in the second direction while the cartridge is attached to the injector.