the present invention aims to provide a painless means to deliver a sizeable drug load into the body . as discussed previously , the injection method is painful , partially due to the insertion of the needle into a body , but more significantly due to injecting a finite volume of drug into the body , which has to make space for that finite volume . the present invention achieves its objectives by two principles . the first principle is that when a cannula is rapidly inserted into the body in a substantially perpendicular manner , provided that the size is small enough , i . e . gauge size of 27 g to 34 g , i . e . with outer diameter between 0 . 4 mm - 0 . 18 mm and that the insertion speed exceeds 1 m / s , the insertion of the cannula into the body is quite painless . therefore , the present invention incorporates a rapid perpendicular insertion of cannula to eliminate pain due to needle insertion . the second principle is that pain is incurred only when the occupied volume caused by the implantation is increased ; for example , injecting liquid drug into the body increases the occupied volume as the body needs to make space for the liquid , which causes pain . instead of injecting any drug , which causes the body to make up the occupied volume for the drug ( which is very painful ), the present invention pre - loads a drug load 320 in the cannula 300 and rapidly inserts the drug - loaded cannula 300 into a body , after which the cannula 300 is retracted while keeping the drug load 320 in the body . this is achieved by having an inner rod 340 which is disposed in the cannula 300 to hold the drug load 320 in place during the retraction of the cannula 300 . in this way , the occupied volume caused by the insertion of the cannula 300 does not increase , but it actually decreases after the cannula 300 is retracted , causing no pain . once the drug load 300 is disposed in the body , it is wetted by the interstitial fluid in the tissue and is fused to the tissue in the body and will not leave the body easily . finally , the cannula 300 and the inner rod 340 are removed from the body completely . it is worth noting that while the insertion of the cannula 300 requires high speed , such as 1 m / s or more , the retraction of cannula 300 requires much lesser speed to prevent the drug load 320 from ‘ splashing ’ when the cannula 300 retracts . the reason is that the drug load 320 is always in physical contact with the inner surface of the cannula 300 , if the cannula 300 retracts in high speed , the surface friction will pull the drug load 320 together , the consequences are a portion of drug may stay in the cannula , and that the drug load 320 may be dispersed to other undesirable depths , causing the drug delivery un - controllable . the retraction speed can be achieved by reducing the actuation speed provided by a compression spring 280 . the speed reduction method may be employing a sliding piston that remains in good contact with the stationary surface during sliding , dampening the initial actuation force of the compression spring 280 . the sliding pistons are made of silicone rubber , or any material that is able to provide firm contacts between sliding surfaces . the retraction speed for the cannula should be less than 20 mm / s to ensure good implant quality . the present invention incorporating these two principles can be represented by two preferred embodiments , which are discussed in the following paragraphs . fig1 - 6 describe the first preferred embodiment and fig7 and 8 describe the second preferred embodiment . now , we will describe the first preferred embodiment of the present invention . in fig1 , a perspective view of the device ( first preferred embodiment ) 100 is presented . the first preferred embodiment 100 comprises a housing 120 and a protective cap 140 , which is removed when the device is in use . fig2 shows a front view of the device 100 without the protective cap 140 . in this figure , the device 100 further comprises a trigger 200 , a slider 220 , a first piston 240 , a second piston 260 , a compression spring 280 , a cannula 300 , which has a beveled tip pointing forward , i . e . pointing away from the housing 120 , and a sliding slot 160 disposed on the housing 120 . although not shown in the figure , it is important to know that there is an inner rod 340 and a drug load 320 disposed within the cannula 300 . the first piston 240 is fastened to the inner rod 340 and the first piston 240 will resist any unwanted movement due to its firm contact with the housing 120 . similarly , the second piston 260 is fastened to the cannula and the second piston 260 will resist any unwanted movement due to its firm contact with the housing 120 . the material for making the pistons is silicone rubber , or any material that remains in good contact between sliding surfaces . the device 100 relies on manual insertion . fig3 shows how the device 100 operates for implanting a drug load into the body painlessly . first , the protective cap 140 ( not shown ) is removed to expose the trigger 200 , and the device 100 is brought near to a skin site with the trigger 200 pointing at the skin site . next , the device 100 is compressed against the skin ; this action pushes the trigger 200 rearward and at the same time rapidly inserts the cannula 300 in to the body . this rapid insertion by manual compression can be achieved by providing a thrust to the skin site while holding the device 100 . the slider 220 , to which the cannula 300 is fastened , which is latched originally , resists the penetration force exerted on the cannula 300 . at the same time , the first piston 240 , which is fastened to the inner rod 320 ( not shown ) and the second piston 260 , which is fastened to the cannula 300 , are held firmly in their respective position by surface friction . the pistons are made of silicone rubber or any other material which provides excellent compressibility and surface friction as seen in typical syringe plunger . the trigger 200 serves to conceal the cannula 300 when not in use . as the trigger 200 continues to be pushed rearward , it engages and unlatches the slider 220 ; as a result , the compressed compression spring 280 releases its potential energy and pushes rearward the slider 220 , which is fastened to the second piston 260 and the cannula 300 , sliding on the sliding slot 160 . this action retracts the cannula 300 while it is still in the body , disposing the drug load 320 to the body . the compression spring 280 continues to push the slider 220 and the second piston 260 rearward until the second piston 260 hits the first piston 240 , after which both pistons 240 , 260 move rearward together . as the two pistons 240 , 260 move rearward together , the cannula 300 and the inner rod 340 retract from the body together completely . this completes the drug implant process . the implanted drug load is properly disposed in the desired depth , normally within penetration depth of 1 mm - 25 mm under the skin . it is vital to understand the exact mechanism of how the implant of drug load into a body can be achieved . fig4 to 6 show the close - up schematic diagrams for implanting a drug load into a body using the device 100 . fig4 shows the device after the cannula is inserted into the body . as shown in fig4 , the cannula 300 is inserted in the body with depth of 1 mm - 25 mm ( intradermal to intramuscular range ), the drug load 320 is disposed within the cannula 300 near the tip ( i . e . the forward position ) and the inner rod 340 is disposed within the cannula 300 and right behind the drug load 320 ( i . e . the rearward position ). the cannula 300 can be made of typical hypodermic needle with a beveled tip and the needle size ( gauge size ) ranges from 27 g - 34 g , i . e . with outer diameter between 0 . 4 mm - 0 . 18 mm and inner diameter between 0 . 2 mm - 0 . 1 mm . the cannula 300 is fastened to the second piston 260 and the slider 220 . two main functions of the cannula 300 are to penetrate the body and to carry the drug load 320 to the desired depth . fig5 shows the state after the cannula 300 is retracted from the body , disposing the drug load 320 . it can be seen that the inner rod 340 which remains stationary prevents the drug load 320 from sticking to the cannula 300 . the inner rod 340 is a metal wire or plastic rod with a diameter the same as the inner diameter of the cannula 300 , which is fastened to the first piston 240 . fig6 shows the state after both the cannula 300 and the inner rod 340 are retracted from the body , leaving the drug load 320 in the body . the drug load 320 is made of solid drug with total volume of 0 . 16 ul - 0 . 63 ul , or 0 . 16 mg - 0 . 63 mg of active pharmaceutical ingredient ( this is a very rough conservative estimate ). the first preferred embodiment of the present invention can be used with a spring loaded applicator , which is shown in fig7 and 8 . in this configuration , the first preferred embodiment uses a spring applicator 500 to propel the device 100 toward the body for consistent and repeatable insertion speed . the spring applicator 500 comprises a slidable casing 520 , a transparent cap 540 , a returning spring 560 , an actuation spring 580 , a button 600 , and a vault 620 . when in operation , device 100 is loaded into spring applicator 500 and is attached to the vault 620 . next , the slidable casing 520 is pulled backward to compress the actuation spring 580 , and subsequently the returning spring 560 will return the slidable casing 520 back to its original position . then , the spring applicator 500 is pointed to a body site with the transparent cap 540 resting on the skin site such that the spring applicator 500 is largely perpendicular to the body site . lastly , the button 600 is depressed to release the vault 620 and the actuation spring 580 propels the device 100 towards the body with the desired speed ( i . e . at least 1 m / s ) for achieving consistent and repeatable rapid insertion . once the device 100 is propelled to hit the body and the cannula is inserted into the body , the retraction of the cannula 300 and the inner rod 340 will automatically be carried out as shown in fig3 and fig4 - 6 . there is a need to provide a simpler device to carry out the drug implant function in the present invention . fig9 shows the perspective view of the second preferred embodiment of the present invention , the drug implanting device 1000 , which is a simplified version of the first preferred embodiment . fig1 shows the exploded view of the drug implanting device 1000 . the drug implanting device 1000 comprises a top casing 1100 a and a bottom casing 1100 b , a lever button 1200 disposed on the top casing 1100 a , a compression spring 1300 , a cannula with a beveled tip 1400 , a cannula holder 1500 on which the cannula with a beveled tip 1400 is fastened , an inner rod 1600 slidably disposed within the cannula with a beveled tip 1600 , a rod stopper 1700 on which the inner rod 1600 is fastened , and a drug load 1800 disposed within the tip of the cannula with a beveled tip 1400 . the drug load 1800 is disposed at the tip of the cannula 1400 and the inner rod 1600 is disposed adjacent to the drug load 1800 within the cannula 1400 such that drug load 1800 is held stationary by the inner rod 1600 when the cannula with a beveled tip 1400 is retracted , thereby disposing the drug load 1800 in the skin 2000 . fig1 ( a ) to ( d ) shows the operation of the drug implanting device 1000 . in the initial stage , the cannula 1600 is exposed outside the drug implanting device 1000 . as shown in fig1 ( a ) , the cannula 1600 is rapidly inserted into the skin 2000 by hand so that the drug load 1800 is buried in the skin 2000 . next , as shown in fig1 ( b ) , the lever button 1200 is depressed , causing a turning moment 3000 , thereby unlatching the lever latch 1200 a from the cannula holder 1500 , which in turn releases the compressed spring 1300 . the compressed spring 1300 pushes the cannula 1400 and the cannula holder 1500 backward so as to expose the drug load 1800 in the skin 2000 . during this retraction of cannula 1400 , the inner rod 1600 is held stationary by the rod stopper 1700 . finally , the inner rod 1600 and the cannula 1400 are removed from the skin site , leaving behind the drug load 1800 in the skin .
the present invention relates to a drug implant device which delivers a drug load to the body painlessly . the present invention achieves the painless drug implantation by adopting two principles : rapid perpendicular insertion of fine cannula is painless and that pain is incurred only when the occupied volume caused by the implant process is increased . therefore , instead of inserting a cannula and injection a volume of drug , which increases the occupied volume of the injection process due to additional volume of the drug , the present invention retracts the cannula in order to dispose the drug into the body . the retraction of cannula does not increase the occupied volume therefore incurs no pain . in the preferred embodiment , the drug implant device comprises a cannula with a bevelled tip , a drug load and an inner rod , wherein the drug load and the inner rod are slidably disposed within the cannula , and that the drug load is disposed at the bevelled end of the cannula and that the inner rod is disposed adjacent to the drug load .