Vented needle for medical liquids
BACKGROUND OF THE INVENTION 
     Many drugs are supplied to pharmacies in a dry or lyophilized form. These drugs are often supplied in rubber stoppered vials with a small portion of their internal volume containing the dry or lyophilized powder. Before such drugs can be used, the lyophilized powder must be dissolved in a sterile liquid. Aftr the lyophilized powder has been dissolved, it can then be extracted from the vial in small unit doses. 
     In the past, there has been a problem with quickly injecting the sterile dissolving liquid into the mixing vial. Small hypodermic needles with a sharpened beveled forward end, restricted liquid flow to a slow rate. Larger diameter double cut hypodermic needles sometimes cored the rubber stopper causing the needle to plug or a small rubber particle to fall into the vial. In addition, double cut hypodermic needles directed the liquid in a straight longitudinal stream causing its mixing force to be directed to only a small area near the center of the vial. 
     Also, with conventional metal hypodermic needles, there was a problem with pressure buildup. As liquid began to fill the vial, air within the vial was compressed. Upon removing the liquid filling syringe needle, the compressed air remained in the vial. Subsequently, when withdrawing small samples of the dissolved medicament from the vial, the operator had to be careful the pressure did not urge a plunger of a unit dose syringe rearwardly to inadvertently cause an overdose in the syringe. 
     SUMMARY OF THE INVENTION 
     We have overcome the above problems with a new thermoplastic vial filling needle that has one or more side delivery ports for turbulently injecting liquid into the container for rapid mixing with the dry powder. This improved needle has a closed forward end to substantially eliminate the coring problem, and a special air vent groove to prevent pressure buildup during liquid injection into the vial. The special needle also has a series of wing stop members near a rear of the vent groove to prevent overinsertion of the needle into the vial stopper to insure the vent groove is always exposed to the atmosphere. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view showing the needle connected to a filling syringe injecting liquid into a vial; 
     FIG. 2 is an enlarged sectional view of the needle of FIG. 1, without the attached syringe, and with only a portion of the vial stopper shown; 
     FIG. 3 is a second embodiment of the needle shown with a filter, and this sectional view as shown most readily at the lower end is taken at 90° to that section taken in FIG. 2; and 
     FIG. 4 is a bottom plan view of FIG. 3 taken along lines 4--4. 
    
    
     DETAILED DESCRIPTION 
     In FIG. 1 the needle is shown generically as numeral 1 and is connected to a conventional hypodermic syringe 2. Syringe 2 has a Luer-lock collar 3 threadingly engaged with the needle 1. A cannula 4 of a needle (shown in dotted line) extends through a closure of vial 5. As shown in the broken away section at the bottom of FIG. 1, this vial contains a lyophilized powder drug 6, as well as a large portion of air 7. During the filling operation, shown in FIG. 1, a plunger 8 of syringe 2 is manually moved in a downward direction to turbulently spray liquid in a lateral direction from side ports 9 and 10 of cannula 4. The precise details of the special needle are better shown in the enlarged view of FIG. 2. Here the generic needle includes a cannula 4 and a hub 11. Hub 11 is designed to sealingly engage with the Luer-lock collar 3 and tapered Luer adapter (not shown) of syringe 2. As shown in FIG. 2 the cannula has a central passage 12 that extends to a forward end 13. Adjacent forward end 13 is lateral side port 10. Because of the 90° rotation from the view shown in FIG. 1, side port 10 appears to the rear of the viewer rather than to the right of the viewer. Along a right side of FIG. 2 is a vent groove 14 extending from a forward end 15 to a rearward end 16. The forward end 15 of groove 14 lies adjacent side port 10 so that a small protrusion of the needle&#39;s forward end beyond the inner surface of resilient rubber stopper 17 exposes the vial&#39;s interior to both a liquid discharge port and an air vent. 
     The forward end portion of cannula 4 is closed and has a generally conical forward tip 18 that terminates in a solid puncture point 19. This tip configuration substantially eliminates the coring problem with previous openended bevel cut hypodermic needles that were forced through rubber stoppers. 
     Near a juncture of the cannula 4 and hub 11 are a series of wings, two of which are shown at 20 and 21. These wings respectively have abutting surfaces 22 and 23 that engage an upper surface of the vial stopper. This limits the insertion distance of the needle, so a portion of the vent groove 14 adjacent its rear end 16 is always exposed to the atmosphere. 
     In the second embodiment of the invention shown in FIG. 3, the needle is identical to that shown in FIG. 2 with the exception of the optional filter 24 in the FIG. 3 embodiment. This filter 24 can act to strain out particulate matter from liquid within the syringe tube, and acts as an additional safety feature. The bottom end of the needle of FIG. 3 has this section taken at a 90° rotation from that section of FIG. 2. Hence, side ports 25 and 26 of the FIG. 3 embodiment correspond to the side ports 9 and 10 of the FIG. 1 embodiment. The arrows show the direction of lateral liquid flow from the two side ports. 
     The relationship of the two side ports 25 and 26 and their relationship to vent groove 27 in the FIG. 3 embodiment is best shown in FIG. 4. The vent groove and side ports are circumferentially spaced 90° apart to prevent air from being sucked into the needle during drug aspiration. Bordering the edges of groove 27 are generally triangular segments 28 and 29 which extend longitudinally along the cannula. This gives the circumferential shape of the cannula a somewhat teardrop configuration. By use of the triangular segments 28 and 29, groove 27 does not interfere with the structural rigidity of the cannula. With this configuration, the cannula&#39;s external diameter is kept to a minimum to decrease drag when puncturing the vial&#39;s rubber stopper. 
     In the foregoing description the needle has been described as an implement for injecting liquid into a vial for mixing with dry lyophilized drugs. If desired, a separate sterilized needle of the same configuration shown in FIGS. 2 or 3 can be used to withdraw the liquid dissolved medicament from the vial. In such situation, the filter 24 of FIG. 3 would act to prevent particulate matter within the vial, from being sucked into the syringe. When the filtered needle to FIG. 3 is used to inject diluent into a vial as in FIG. 1, the needle also filters the diluent entering the vial. 
     The needle of this invention works very well when the cannula and hub are injection molded as a one-piece unit of transparent thermoplastic, such as polycarbonate. In this needle it has been found that a groove that is from 0.005 to 0.015 inch (0.127 to 0.381 millimeters) wide and is from 0.010 to 0.030 inch (0.254 to 0.762 millimeters) deep. The distance from the side port to the abutting surfaces 22, 23, of wings 20, 21 is preferably 0.300 to 0.500 inch (7.62 to 12.7 millimeters). 
     The needle as described above and with the dimensions specified work exceptionally well for rapidly injecting liquid into a vial without pressure buildup and without stopper coring. Although the needle can be used with an inverted (stopper downward) vial to extract liquid, it has been noted that occasionally some liquid seepage will pass through the air vent groove. 
     In the foregoing description, specific embodiments have been used to describe the invention. However, it is understood by those skilled in the art that certain modifications can be made to these embodiments without departing from the spirit and scope of the invention.