Method of using a needle assisted injection device having reduced trigger force

1 . A method for delivering a medicament to a subject in need thereof, the method comprising injecting the medicament in the subject using an injector comprising:

a trigger mechanism including:

a trigger member disposed about an axis, the trigger member having a trigger member protrusion and an opening defined by a trigger member opening wall, and

a ram assembly having a ram configured to pressurize a medicament container for expelling a medicament therefrom, the ram assembly further having a trigger engagement member configured to be positioned in the opening and engage the trigger member opening wall when the trigger member is in a pre-firing condition;

an energy source associated with the ram for powering the ram to expel the medicament; and

a guard including a guard aperture slidably engaged with the trigger member protrusion, such that the guard axially translates without movement of the trigger member for a predetermined distance and an axial translation of the guard beyond the predetermined distance causes an axial translation of the trigger member in a proximal direction from the pre-firing condition to a firing condition in which the trigger engagement member is disengaged from the trigger member opening wall to allow the energy source to fire the ram.

2 . The method of claim 1 , wherein the energy source is configured to pressurize the medicament to between about 80 psi and about 1000 psi to jet inject the medicament.

3 . The method of claim 1 , wherein a needle connected to the medicament container is exposed by the guard upon a proximal movement of the guard, wherein the guard is retractable.

4 . The method of claim 3 , wherein the needle is in fluid communication with the medicament container for injecting the medicament expelled therefrom during firing.

5 . The method of claim 3 , wherein the energy source and the needle are configured for jet injecting the medicament through the needle.

6 . The method of claim 3 , wherein the medicament is injected through the needle at a needle insertion depth of about 8 mm or less.

7 . The method of claim 3 , wherein the medicament is injected through the needle at a needle insertion depth of about 6 mm or less.

8 . The method of claim 3 , wherein the medicament is injected through the needle at a needle insertion depth of about 4 mm or less.

9 . The method of claim 1 , wherein up to about 3 mL of the medicament is delivered.

10 . The method of claim 1 , wherein about 0.5 mL, about 1 mL, about 1.5 mL, about 2 mL, about 2.5 mL or about 3 mL of the medicament is delivered.

11 . The method of claim 1 , wherein about 0.5 mL of the medicament is delivered.

12 . The method of claim 1 , wherein the medicament is delivered at a rate of between about 0.2 mL/sec and about 0.75 mL/sec.

13 . The method of claim 1 , wherein the medicament is delivered at a rate of about 0.2 mL/sec, about 0.3 mL/sec, about 0.35 mL/sec, about 0.4 mL/sec, about 0.45 mL/sec, about 0.5 mL/sec, about 0.55 mL/sec, about 0.6 mL/sec, about 0.65 mL/sec, about 0.7 mL/sec, or about 0.75 mL/sec.

14 . The method of claim 1 , wherein the medicament comprises a thrombolytic.

15 . The method of claim 14 , wherein the thrombolytic is a P2Y12 inhibitor.

16 . The method of claim 1 , wherein the medicament comprises an aqueous solution.

17 . The method of claim 1 , wherein the medicament comprises an androgen.

18 . The method of claim 17 , wherein the androgen includes testosterone or a derivative or ester thereof.

19 . A method for delivering a medicament to a subject in need thereof, the method comprising injecting the medicament in the subject using an injector comprising:

a trigger mechanism including:

a trigger member disposed about an axis, the trigger member having a trigger member protrusion and an opening defined by a trigger member opening wall, and

a ram assembly having a ram configured to pressurize a medicament container for expelling a medicament therefrom, the ram assembly further having a trigger engagement member configured to be positioned in the opening and engage the trigger member opening wall when the trigger member is in a pre-firing condition;

an energy source associated with the ram for powering the ram to expel the medicament; and

a guard including a guard aperture slidably engaged with the trigger member protrusion, such that the guard axially translates without movement of the trigger member for a predetermined distance and an axial translation of the guard beyond the predetermined distance causes an axial translation of the trigger member in a proximal direction from the pre-firing condition to a firing condition in which the trigger engagement member is disengaged from the trigger member opening wall to allow the energy source to fire the ram;

wherein the energy source is configured to pressurize the medicament to between about 80 psi and about 1000 psi to jet inject the medicament;

wherein a needle connected to the medicament container is exposed by the guard upon a proximal movement of the guard, wherein the guard is retractable;

wherein the medicament is injected through the needle at a needle insertion depth of about 8 mm or less;

wherein up to about 3 mL of the medicament is delivered;

wherein the medicament is delivered at a rate of between about 0.2 mL/sec and about 0.75 mL/sec;

wherein the medicament comprises a thrombolytic; and

wherein the medicament comprises an aqueous solution.

20 . A method for delivering a medicament to a subject in need thereof, the method comprising injecting the medicament in the subject using an injector comprising:

a trigger mechanism including:

a trigger member disposed about an axis, the trigger member having a trigger member protrusion and an opening defined by a trigger member opening wall, and

a ram assembly having a ram configured to pressurize a medicament container for expelling a medicament therefrom, the ram assembly further having a trigger engagement member configured to be positioned in the opening and engage the trigger member opening wall when the trigger member is in a pre-firing condition;

an energy source associated with the ram for powering the ram to expel the medicament; and

a guard including a guard aperture slidably engaged with the trigger member protrusion, such that the guard axially translates without movement of the trigger member for a predetermined distance and an axial translation of the guard beyond the predetermined distance causes an axial translation of the trigger member in a proximal direction from the pre-firing condition to a firing condition in which the trigger engagement member is disengaged from the trigger member opening wall to allow the energy source to fire the ram;

wherein the energy source is configured to pressurize the medicament to between about 80 psi and about 1000 psi to jet inject the medicament;

wherein a needle connected to the medicament container is exposed by the guard upon the proximal movement of the guard, wherein the guard is retractable;

wherein the medicament is injected through the needle at a needle insertion depth of about 8 mm or less;

wherein up to about 3 mL of the medicament is delivered;

wherein the medicament comprises a thrombolytic; and

wherein the medicament comprises an aqueous solution.