MXPA00008113A - Retracting needle syringe - Google Patents

Abstract

The syringe has a re-use prevention feature where the plunger rod (26) and needle hut (38) are destroyed and the needle (64) is retracted into the rod. This feature requires only an increase of force along the same line of action as the injection stroke. This allows for safe, one-handed injection, which is critical in some situations. The syringe also minimizes the amount of wasted medication because the plunger rod tip (28) occupies the entire volume inside de the barrel (20). The retracting needle syringe uses standard luer-lok fittings and can be used with a variety of standard needles that do have rectracting cannula. A large gauge needle can be used to fill the syringe from a vial or other container before attaching the savety needle for injection. Lastly, the plunger can be completely encapsulated by the barrel prevents re-use of the syringe and allows for safe and easy disposal.

Description

RETRACTABLE NEEDLE SYRINGE DESCRIPTION OF THE INVENTION This invention relates generally to a medical device with characteristics of safety edges. More particularly, this invention relates to a syringe for medical use having a retractable needle feature that allows for safe and simple syringe removal and avoids reuse by destroying the plunger rod and needle mass and retracting the needle inside. of the plunger rod.

BACKGROUND OF THE INVENTION Hypodermic syringes are well known to be used to deliver fluids such as drugs, for example, to patients. A traditional hypodermic syringe commonly includes a syringe body having opposite proximal and distant ends. A cylindrical chamber wall extends between the ends and defines a fluid receiving chamber. The proximal end of the traditional syringe body is substantially open and receives a plunger in fluid-tight coupling. The distal end of the traditional syringe body includes a passage communicating with the chamber. A needle cannula is mounted to the distal end of the traditional syringe body so that the lumen of the needle cannula communicates with the passageway and chamber of the syringe body. The movement of the plunger in the proximal direction removes the fluid through the lumen of the needle cannula and into the chamber. Movement of the plunger in a proximal to distant direction drives the fluid from the chamber and through the lumen of the needle chamber. In recent years, considerable effort has been expended in providing a syringe for medical use that is safe and easy to discard and not reusable. Some of these syringes include a retractable needle safety feature. However, these mechanisms are somewhat complex, difficult to use and can increase manufacturing costs while decreasing efficiency in the manufacturing process. For example, a retractable needle safety syringe of one type requires the user to push the plunger completely into the body until the coupling is detected and an audible click sound is heard. The user then opens a safety fastener at the distal end of the body. The plunger is completely retracted then. This leads the needle back into the syringe body. The plunger is released immediately and inserted into the open body, sealing the needle inside the syringe for safe removal. Another design incorporates a plunger that is pushed forward and rotated. An integrally molded spring locks it into the mass of the needle. The plunger rod is withdrawn backwards and then the tension in a spring is released towards the angle in a mass and the needle to the side, thus disarming the syringe.

Another retractable safety syringe comprises a plunger, a body, an elastomer piston, the mass and a needle This design allows a used needle to be withdrawn into the syringe body after use and automatically tilts laterally. the body and the needle mass that allow the needle mass to engage and disengage within the body. Clamps in the form of darts on the internal circumference of the mass selectively couple complementary clamps on the tip of the plunger. The plunger can be freely moved backwards and forward until retraction of the desired needle At that moment the plunger is pushed forward into the mass of the needle and turned to the left moving the piston cams inside the mass and locking together the two Action by arrangement of cams simultaneously compresses a molded spring integrally on the tip of the plunger Continuous rotation decouples to the mass and release the coupled components to be pulled backwards The plunger is retracted until it is stopped by the tabs on the body that prevents the exit from behind As the needle clears the mouthpiece of the body, the compressed spring is released, bending the needle towards the side wall of the body The retention of the needle is achieved and the needle is blocked by the front wall of the body allowing the syringe disarmed with the used needle to be stored safely in the body before elimination Each of these constructions composed of retractable syringe needles has certain disadvantages. Many of them have complicated functional parts and require complicated procedures to activate the safety mechanisms. Besides that these mechanisms are in some way complex, they also increase the manufacturing costs due to its multi-component configuration, and decrease the efficiency in the manufacturing process. Therefore, there is a need in the art that allows the safe and simple removal of a syringe and avoids reuse. The device must allow the use of a variety of standard needles for purposes of I swim BRIEF DESCRIPTION OF THE INVENTION A retractable needle syringe for medical use that allows the safe and simple removal of the syringe and avoids reuse while having minimal components comprises a syringe body, a plunger rod and in needle assembly The assembly The needle assembly is attached to the distal end of the syringe body. The needle assembly comprises an internal mass, an external mass and a spring. The internal mass has a fragile portion and a penetration member fixedly attached. A spring is placed on the end portion of the syringe body. penetration The internal mass is coupled within the external mass to provide compression to the spring The piston rod has a piston point and a chamber The chamber has a closed end and an open end The open end is sealed by the tip of the piston piston rod, the chamber and the tip of the plunger are all in one piece The cutting means are adjacent to the end of the chamber to provide passage of the chamber through the tip of the plunger By compressing the plunger rod completely and applying the axial force directed in a distant manner, the fragile portion of the internal mass is broken and the tip of the plunger is dislodged by means of the cutting means thus allowing the spring to move the penetration member to enter the chamber. A retainer is attached to the plunger rod and positioned around the tip of the plunger so that the tip of the plunger is substantially interrupted by the seal when the plunger tip is dislodged The cutting means may be a cutting ring that is embedded in the distal end of the syringe body The cutting ring has a single-trim sheet In another embodiment, the cutting means are a fragile portion that surrounds the tip of the plunger The fragile portion of the internal mass requires less force to break than the tip of the plunger so that at the tip of the plunger it breaks the fragile portion of the internal mass when the plunger is completely depressed and the tip of the plunger is dislodged by the cutting means In the mode where the cutting means are a fragile portion that surrounds the plunger tip, the tip of the plunger is dislodged by the fragile portion that surrounds the tip of the plunger when the plunger is fully compressed. The penetration member can enter the chamber by the force of the spring when the fragile portion of the internal mass is broken by the tip of the plunger. plunger when the plunger rod is completely depressed In the mode where the cutting means are a cutting ring, the plunger tip is dislodged by the action of the cutting ring when the plunger is fully depressed. Thus, the penetrating member can enter the chamber by spring force when the fragile portion of the internal mass is separated by the tip of the stem only when the plunger rod is fully depressed In both modes, the internal and external mass are dimensioned so that the external diameter of the internal mass and the internal diameter of the external mass provide a permanent pressure adjustment between both components The fragile portion of the internal mass allows entry of the penetration member into the chamber when the plunger rod is fully depressed and the plunger tip is dislodged by the cutting means. A spring fitting on the proximal end of the syringe body provides the locking of the plunger rod by the body when the plunger rod is completely depressed Therefore, the present invention protects against reuse.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view of the present invention. Figure 2 is an exploded perspective view of the present invention. Figure 3 is a cross-sectional view of the syringe of Figure 1 taken along line 3-3. Figure 4 is an enlarged view of Figure 3. Figure 5 is a cross-sectional view of the present invention with the plunger rod fully depressed. Figure 6 is an elongated cross-sectional view of the present invention wherein the cutting means is a fragile portion that surrounds the tip of the plunger. Figure 7 is an enlarged cross-sectional view showing the function of the cutting means in Figure 6. Figure 8 is an elongated cross-sectional view of the present invention where the cutting means is a cutting ring. Figure 9 is an elongated cross-sectional view of the present invention showing the function of the cutting means in Figure 8.

DETAILED DESCRIPTION While this invention is satisfied in many different forms by the embodiments, it is shown in the drawings and the preferred embodiments of the invention will be described herein in detail with the understanding that the current description will be considered illustrative of the principles OF THE INVENTION It is not intended that it limit the scope of the invention to those illustrated embodiments. The scope of the invention will be measured by the appended claims and their equivalents. Referring to the drawings, Figures 1-9 illustrate the present invention of the invention syringe. retractable needle 18 Shown in Figure 1 and 2 is a syringe body 20 for holding the liquid This liquid may be medicament, saline solution, wash solution or any other type of injectable liquid used for medical purposes The body has a proximal end 22 and a distant proximal end 24 A plunger rod 26 is placed on the body and has a plunger tip 28 The plunger rod also has a chamber 30 therein The chamber has a closed end 32 and an open end 34 The open end is preferably sealed by the plunger tip Preferably, the plunger rod is molded as a part comprising the bar, the tip of the plunger and the chamber The tip of the plunger can be hermetically sealed to prevent the entry of air or liquid inside the plunger rod with the tip of the plunger, the chamber and the plunger rod made from a single piece The sealed plunger rod allows the plunger to create positive or negative pressure in the body to extract and inject the liquid Once this plunger tip separates, the positive or negative pressure in the body is removed to extract and inject the liquid and the syringe can not be used. The plunger rod also defines an "A" axis shown in Figures 3 and 5. The needle assembly 36 is attached to the distal end of the body. The needle assembly can be linked through various methods known to one skilled in the art. These joining methods include, but are not limited to, thermal welding, thermal stacking, adhesive bonding, ultrasonic welding, in-mold assembly techniques, and snap or spring adjustments. Preferably, the needle assembly is removably attached to the distal end of the body. The needle assembly has an internal mass 38, an external mass 40 and a spring 42. The internal mass has a fragile portion 44 and a penetrating member 46 fixedly attached. The spring is placed on the penetration member. Preferably, the penetrating member has a sharp distal end 62 and is a needle cannula 64. However, it can be blunt as in the case of a blunt cannula 80 as shown in Figures 8 and 9 which are for injection ports. intravenous The penetrating member may also be of any other type of point at the far end which allows the liquid to be injected. The inner mass is engaged within the external mass to provide compression to the spring. Because the body preferably utilizes the luer lock accessory number of standard ISO 594-1 and 594-2 94, and the needle assembly is removably attached, the present invention can be used with a variety of standard needles that do not have a retractable cannula. This gives the end user the ability to use a standard large-bore needle to fill the syringe from a vial or other container before attaching the needle assembly for injection. The needle assembly can be designed within a wide variety of sizes. syringe and needle Thus, the present invention of the retractable needle syringe allows the use of a variety of standard needles that does not have a retractable cannula The cutting means are also included in the retractable needle syringe The cutting means are adjacent to the end open the camera The cutting means provide passage into the chamber by the evacuation of the plunger tip when the plunger rod is fully depressed along the axis "A" One of the advantages of the present invention is that only an increase in force of the plunger rod along the same line of action as the injection stroke is required to retract the penetration member The activation of the needle assembly allows the penetration member to enter the chamber only requiring an increase in force of the piston rod along the "A" axis using an axial force directed remotely with one hand This activation technique allows the injection with one hand in a secure manner, which is critical in some health care situations When the plunger rod is completely depressed, the fragile portion of the inner mass separates releasing and allowing retraction of the penetration member and the plunger tip is dislodged by the means cutting, thus allowing the penetration member to enter the chamber. The penetration member is held in the chamber by the force of the uncompressed spring or by the larger diameter of the first fracture point 86 of the plunger tip. Preferably, The retractable needle syringe has a fragile portion of the internal mass that requires less force to break than the plunger tip so that the plunger tip breaks the fragile portion of the internal mass when the plunger rod is fully depressed and the tip of plunger is dislodged by the cutting means. Once the plunger tip is dislodged by the syringe it can not be reused. because the positive or negative pressure is now removed which was generated by the plunger rod to extract or inject the fluid Preferably, when the fragile portion of the internal mass is broken, the needle assembly can not be used because the spring can now move or retract the penetration member. The penetration member can preferably enter the chamber in the plunger rod when the plunger tip is dislodged by the cutting means. Therefore, only an increase in the force of the bar of plunger along the same line of action as the injection stroke, Axis "A", is required to retract the penetration member The retractable needle syringe also minimizes the amount of fluid or medication wasted after injection because the plunger tip occupies the entire volume within the distal end of the body. Typically, syringes of the prior art create a volume of inactive space between the connection of the syringe and the needle mass An advantage of the present invention is that this volume can be reduced by having the tip of the plunger on the bar of the plunger that extends within the volume of inactive space thus occupying all the volume which minimizes the amount of fluid or medicine wasted after injection This waste is important to be minimized especially when an expensive drug such as eptopoietin related to dialysis, filgrastim or many of the new recombinant biological products The syringe needle is typically used, the retractable needle syringe has the penetrating member with a sharp distal end. This penetrating member in this embodiment is a needle cannula 64, although, it is not necessary to have a sharp distal end. Such is the case when a blunt 80 cannula is used in the needle assembly as shown in FIGS. 8 and 9 The body of the retractable needle syringe is commonly made of a thermoplastic material. Such a material may be, but is not limited to, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, pohcarbonate, polyesters, and various mixtures thereof. polymer. The retractable needle syringe may also have an additional element, a retainer 48 which is attached to the plunger rod and positioned around the plunger tip so that the tip of the plunger is substantially and preferably uninterrupted by the retainer when the tip of the plunger is evicted. The retainer allows the medicament to move from the proximal end to the distal end of the syringe body. However, the retainer is not always necessary for such a function. Such is the case when the plunger rod is designed without the retainer and provides a movement of the fluid from the proximal end to the distal end during the ejection movement. In this embodiment, the plunger rod and the syringe body are dimensioned to provide positive and negative pressure to the movement of the plunger rod. The cutting means have several modalities.

Preferably, the cutting means is a fragile portion 60 that surrounds the tip of the plunger as shown in Figure 6. As shown in Figures 6 and 7, the retractable needle syringe allows the penetration member to enter into the the camera. By fully depressing the piston rod along the "A" axis and applying the axial force directed away from the piston rod along the "A" axis, the fragile portion of the internal mass breaks and the tip of the plunger is dislodged by the fragile portion that surrounds the tip of the plunger. Therefore, the penetration member fixedly attached to the internal mass can enter the chamber of the piston rod. The fragile portion of the internal mass requires less force to break than the fragile portion that surrounds the tip of the plunger so that the tip of the plunger breaks the fragile portion of the internal mass when the plunger rod is fully depressed. The fragile portion surrounding the tip of the plunger is preferably broken when it meets the distal end of the body. In this case, the tip of the plunger would break the fragile portion of the inner mass when it is fully depressed and by additional force in the near-to-distant direction along the "A" axis. Along the same axis "A", the tip of the plunger meets the distal end of the plunger that would break the fragile portion of the tip of the plunger thereby allowing the penetration member to enter the chamber. The penetration member enters the chamber by force from the compressed spring. The fragile portion that surrounds the tip of the plunger can also be activated by breaking simultaneously with the fragile portion of the internal mass. However, this is not preferably favored due to the potential of the fragile portion of the inner mass that does not break completely. Another way to activate the fragile portion that surrounds the tip of the plunger is after the fragile portion of the internal mass breaks, the force applied to the plunger rod is reacted by the fully compressed spring until the tip of the plunger is dislodged. plunger. Once the plunger tip is dislodged, and only then, the spring moves the penetrating member into the plunger chamber. In all those embodiments, the end user of the present invention provides all the force that is necessary to break the internal mass and the tip of the plunger while pressing the plunger rod along the same axis and direction as the injection. Also shown in Figures 6 and 7 is the internal mass having an internal diameter 52 and an outer diameter 54. The external mass also has an internal diameter 56 and an external diameter 58. The external diameter of the internal mass and the internal diameter of the external mass are dimensioned to provide a permanent pressure adjustment interface 68 between the internal mass and the external mass. The fragile portion of the internal mass allows retraction of the penetration member on the plunger rod which is completely depressed along the axis "A" and when the plunger tip is dislodged by the cutting members then the penetration member enters. to the camera. The cutting members may be the fragile portion that surrounds the tip of the plunger or a cutting ring 76 embedded in the distal end of the body as shown in Figure 8 and Figure 9. In the preferred embodiment, the cutting means are the fragile portion that surrounds the tip of the plunger. A permanent pressure adjustment is preferred between the external mass and the internal mass. However, there are many ways to join these two components such as, but not limited to, thermal welding, sonic welding, spring adjustments, adhesive bonding and multilayer molding. Once these two components are joined, the spring is compressed. penetration fixedly attached to the internal mass can only be retracted when the fragile portion of the internal handle is broken. The penetration member can only enter the chamber and is therefore dislodged safely when the plunger tip is dislodged by the means Cutting Another modality of the cutting means includes the cutting ring as shown in Figures 8 and 9 In this internal mode, the cutting ring is embedded in the far end of the body. There are several ways to embed the cutting ring inside the syringe body. Some of the ways to do this alternating mode is to hold the cutting ring inside the far end of the syringe body. by thermal welding, adhesive bonding, sonic welding, friction interference and other methods known to one skilled in the art. Preferably, this alternate mode is made by molding insertion of the cutting ring into the distal end of the syringe body. The mold allows the cutting ring to be embedded in the distal end of the syringe body regardless of being removed. In addition, this technique allows assembly efficiency and the production of the retractable needle syringe by eliminating an assembly step. Preferably , the cutting ring has a single-edge blade 78 as shown in FIG. Figure 8 and Figure 9 Cutting ring 76 works as follows By fully depressing the plunger rod along the "A" axis and applying an axial force directed remotely with a single hand to the plunger rod along the axis "A" the fragile portion of the internal mass is broken by the tip of the plunger thereby releasing the penetration member A the additional application of the axial force directed away from the rod of the plunger in the same direction that before, the tip of the plunger is dislodged by the cutting ring which is embedded in the distal end of the body. Then, the penetration member which is fixedly attached to the inner mass enters into the chamber by the force released from the spring. this alternate mode, the fragile portion of the internal mass requires less force to break than the tip of the plunger so that the tip of the plunger breaks the fragile portion of the internal mass when the piston rod is completely depressed by releasing the penetration member The plunger tip is dislodged by the cutting ring when additionally pressing the plunger rod The penetration member that is fixedly attached to the internal mass enters the chamber by spring force Likewise, this action of the spring can assist in the eviction of the tip of the plunger Although the force of the spring is not required to assist in the eviction of the tip of the plunger Referring to Figures 3, 4 and 5, a spring attachment 50 sample at the proximal end of the syringe body The accessory provides the piston rod locking housing through the body only when the plunger rod is fully depressed This feature that also helps to avoid reuse incorporates the use of a standard thumb pressure 85 of the piston rod Therefore, the accessory is in the body and does not involve any special geometry or Dimensional ambient to the standard plunger rod thumb pressure By using a standard plunger rod thumb pressure, the manufacturing benefits The spring adjustment has an inlet angle a and a head width ß The spring adjustment also has a thickness "t" and a length "L" The spring adjustment provides an easy and inexpensive quick way to permanently lock the plunger rod in the body Preferably, the spring adjustment has a tapered thickness "t" instead of a constant thickness because the tension is distributed more uniformly There are several different embodiments that the microencapsulation of the plunger rod can provide in the body of the present invention Some of the embodiments include torsion spring joints, annular spring joints and other cantilever spring joints In the case of torsion spring joints, the deflection is not the result of a bending load as with the cantilever springs although it is due to a torsional deformation of the fulcrum The torsion bar is subjected to the shear stress In the annular spring joints, the joint can be separable or non-separable, depending on the dimension of the spring joint. Non-separable designs should be avoided in annular spring joints due to manufacturing complexity. The preferred spring gasket is a cantilever type spring gasket as shown in Figures 3, 4 and 5 for the spring device. A large portion of the spring joints are simply cantilevered springs, which may be rectangular or of a geometrically more complex cross-section. It is preferred that the design of the spring attachment that is of thickness "t" or length "L" be smoothed from the origin to the hook. In this way, the cross section that holds the load at any point is a more appropriate relationship for the local load. The maximum tension on the material can therefore be reduced and less material is necessary. Good results have been obtained by reducing the thickness "t" of the cantilever element linearly so that its dimensional value at the end of the hook is equal to half the original value. Alternatively, the width of the finger can be reduced to a quarter of the base value. Special attention should be given to this area to avoid stress concentration. In all of the described spring adjustment designs, it is assumed that one of the coupling portions remains substantially rigid. If the two components are of roughly equal stiffness, half of the flex can be assigned to each part. By providing the spring attachment in the retractable needle syringe of the present invention, the plunger rod can be completely encapsulated by the body only which will prevent reuse of the syringe and allow easy and safe removal. The chance of reuse is also minimized by the destruction of the plunger rod and the needle assembly. Once the needle assembly is activated, it is impossible to generate positive or negative pressure in the body to extract or inject the medication.

Claims (34)

1. CLAIMS 1. A retractable needle syringe, comprising: a syringe body for holding liquid, said body having proximal and distant ends; a plunger rod positioned on the body and having a plunger tip, and a chamber therein, said chamber having an open end sealed by the plunger tip, the plunger rod defining an axis; a water assembly attached to the distal end of the body, the assembly having an internal mass, an external mass and a spring; the internal mass has a fragile portion and a penetrating member fixedly attached thereto, the spring placed on the penetrating member, the internal mass engaged within the external mass to provide compression to the spring; and cutting means adjacent to the open end of the chamber to provide passage of the penetration member into the chamber through the plunger tip so that by fully depressing the plunger rod along the axis and applying the axial force directed away from the plunger rod the fragile portion of the internal mass is broken and the tip of the plunger is dislodged, thereby allowing the spring to move the penetration member to enter the chamber. The retractable needle syringe according to claim 1, characterized in that the needle assembly is removably attached to the end of the body 3 The retractable needle syringe according to claim 1 characterized in that the fluid in the body after injection it is minimized by the plunger tip occupying the volume at the distal end of the body 4 The retractable needle syringe according to claim 1, characterized in that the penetrating member has a sharp distal end 5 The retractable needle syringe according to claim 1, characterized in that the penetrating member is a needle cannula 6 The retractable needle syringe according to claim 1, characterized in that the syringe body is made of a thermoplastic material 7 The retractable needle syringe in accordance with Claim 1, characterized in that it also comprises a bonded retainer to the plunger rod and positioned around the plunger tip so that the plunger tip is substantially uninterrupted by the retainer when the plunger tip is dislodged. The retractable needle syringe according to claim 1, characterized in that the means are a cutting ring at the far end of the body 9 The retractable needle syringe according to claim 8, characterized in that the cutting ring has a single-edge blade 10 The retractable needle syringe according to the claim 1, characterized in that the cutting means are a fragile portion that surrounds the tip of the plunger 11 The retractable needle syringe according to claim 1, characterized in that it further comprises a spring attachment on the proximal end of the syringe body, accessory that provides the locking of the plunger rod in the body when the plunger rod is completely depressed 12 The retractable needle syringe according to claim 1, characterized in that the internal mass comprises an external diameter and the external mass comprises an internal diameter, so that the external diameter of the internal mass and the internal diameter of the external mass they are dimensioned to provide a permanent pressure fit between the internal mass and the external mass, and the fragile portion of the internal mass allows retraction of the penetration member by completely depressing the plunger rod, and when the plunger tip is dislodged by the cutting means the penetrating member enters the chamber 13 The retractable needle syringe according to claim 1, characterized in that the fragile portion of the internal mass requires less force to break than the plunger tip so that the tip of the syringe plunger breaks the fragile portion of the internal mass when the plunger rod is fully depressed and the plunger flange is dislodged by the cutting means 14 A retractable needle syringe, comprising a syringe body for holding fluid, the body having proximal and distant ends, a piston rod positioned on the body and having a plunger tip, and a chamber therein, the chamber having an open end sealed by the plunger tip, the plunger tip further comprising a fragile portion surrounding the plunger tip, the plunger rod defining an axis, a water assembly attached to the distal end of the body, the assembly having a internal mass, an external mass and a spring, and the internal mass has a fragile portion and a penetration member fixedly attached thereto, the spring placed on the penetration member, the internal mass engaged within the external mass to provide compression to the spring so that by fully depressing the plunger rod along the axis and applying the axial force directed away from the plunger rod the fragile portion of the internal mass will be mpe and the tip of the plunger is ddged by the fragile portion that surrounds the tip of the plunger, thus allowing the spring to move the penetration member to enter the chamber 15 The retractable needle syringe according to claim 14, characterized because the needle assembly is removably attached to the end of the body 16. The retractable needle syringe according to claim 14, characterized in that the fluid in the body after injection is minimized by the plunger tip occupying the volume at the distal end of the body. 17. The retractable needle syringe according to claim 14, characterized in that the fragile portion of the internal mass requires less force to break than the fragile portion surrounding the tip of the plunger so that the tip of the plunger breaks said fragile portion. of the internal mass when the plunger is completely depressed and the fragile portion that surrounds the tip of the plunger breaks when the tip of the plunger meets the distal end of the body. 18. The retractable needle syringe according to claim 14, characterized in that the cutting member has a sharpened distant end. 19. The retractable needle syringe according to claim 14, characterized in that the penetrating member is a needle cannula. 20. The retractable needle syringe according to claim 14, characterized in that the syringe body is made of a thermoplastic material. The retractable needle syringe according to claim 14, characterized in that it further comprises: a retainer attached to the plunger rod and positioned around the plunger tip so that the plunger tip is substantially uninterrupted by the retainer when the tip of piston is dislodged 22 The retractable needle syringe according to claim 14, characterized in that it further comprises a spring attachment on the proximal end of the syringe body, the accessory that provides the locking assembly of the plunger rods for the body when the plunger rod is completely depressed 23 The retractable needle syringe according to claim 14, characterized in that the internal mass comprises an internal and an external diameter and the external mass comprises an external diameter and an internal diameter, so that the diameter The external mass of the internal mass and the internal diameter of the external mass are dimensioned to provide a permanent pressure fit between the internal mass and the external mass, and the fragile portion of the internal mass allows retraction of the penetration member by completely depressing the plunger rod, and when the plunger tip is dislodged by the portion fragile surrounding the tip of the plunger the penetration member enters the chamber 24 A retractable needle syringe, comprising a syringe body for holding the fluid, the body having proximal and distant ends, the body further comprising a ring cutting at the far end, a plunger rod positioned on the body and having a plunger tip, and a chamber thereon, said chamber having an open end sealed by the plunger tip, the plunger rod defining an axis, a water assembly attached to the distal end of the body, the assembly having an internal mass, an external mass and a spring, the inner mass having a fragile portion and a penetration member fixedly attached thereto, the spring positioned on the penetration member, the inner mass engaged within the external mass to provide compression to the spring so that by fully depressing the plunger rod along the axis and applying the axial force directed away from the piston rod the fragile portion of the internal mass is broken and the tip of the plunger is dislodged by the action of the cutting ring, thus allowing the spring to move the penetration member to enter to the chamber 25 The retractable needle syringe according to claim 24, characterized in that the needle assembly is removably attached to the end of the body 26 The retractable needle syringe according to claim 24, characterized in that the fluid in the body of the injection is minimized by the plunger tip that occupies the volume at the far end of the body 27 retractable needle syringe according to claim 24, characterized in that the cutting ring is a single-edge blade '28. The retractable needle syringe according to claim 24, characterized in that the penetrating member has a sharp distant end. 29. The retractable needle syringe according to claim 24, characterized in that the penetrating member is a needle cannula. 30. The retractable needle syringe according to claim 24, characterized in that the syringe body is made of a thermoplastic material. The retractable needle syringe according to claim 24, characterized in that it further comprises: a retainer attached to the plunger rod and positioned around the plunger tip so that the plunger tip is substantially uninterrupted by the retainer when the tip of plunger is dislodged. 32. The retractable needle syringe according to claim 24, characterized in that it further comprises: a spring accessory on the proximal end of the syringe body; The accessory that provides encapsulated piston rod lock by the body when the plunger rod is fully depressed with one hand along the shaft. The retractable needle syringe according to claim 24, characterized in that the internal mass comprises an internal and an external diameter and the external mass comprises an internal and an external diameter so that the external diameter of the internal mass and the internal diameter of the external mass are dimensioned to provide a permanent pressure fit between the internal mass and the external mass, and the fragile portion of the internal mass allows retraction of the penetration member by fully depressing the plunger rod, and when the tip of the plunger Plunger is dislodged by the cutting ring the penetration member enters the chamber. 34. The retractable needle syringe according to claim 24, characterized in that the fragile portion of the internal mass requires less force to break than the plunger tip so that the plunger tip breaks the fragile portion of the internal mass when the Plunger is completely depressed and the plunger tip is dislodged by the action of the cut.