Abstract:
Syringe for medical use having two chambers for containing powdered drug and diluent. Its construction is practical and economical, being also disposable.

Description:
FIELD OF THE INVENTION 
     The instant invention relates to a double chamber disposable syringe for simultaneous dilution and administration of powdered drugs, of the type marketed with the product to be injected contained therein, all parts and forming elements thereof being duly sterilized, such that, the user may not contact the medicine, or the needle and surrounding regions, before, during and after effecting the injection. In this case, powdered drugs may be used which are diluted at the moment of injection, resulting in several advantages which will be detailed hereinbelow. 
     BACKGROUND OF THE INVENTION--PRIOR ART 
     More particularly, the instant invention relates to a syringe of the above mentioned type comprised by a main cylindrical, hollow body, containing the medicine to be administered, and through which a coaxial plunger is located. In all cases the lower base of said main cylindrical body has an opening through which the rear end of said coaxial plunger projects, and having an annular flange in order that the user may push or pull manually the plunger, according to the desired action. The inner end or head of the plunger tightly fits inside the walls and at the bottom of said main body, such that the variable volume chamber defined therein is always tight and isolated from the outside. Said bottom has, in turn, an outer frusto-conical hollow and coaxial nozzle converging towards its outer end, constituting the plugging means for coupling and fixing the injection needle. 
     The novelty of the invention resides in that the syringe has two chambers: one containing the powdered product and the other the diluent. i.e. it is capable of diluting and administering simultaneously powdered drugs. 
     Such a functional feature, in a disposable syringe, is a consequence of various novel constructive characteristics. 
     It is known that, at present, administration of powdered drugs requires prior preparation of the mixture before introducing it into the syringe, this implying contamination risks even though this procedure is carried out carefully; in order to be diluted, such powdered drugs are subject to handling which may introduce contaminants, said handling comprising solid and solvent pouring from one container to another and then introducing the mixture into the syringe. 
     The instant invention always warrants the use of new syringes and needles, thus preventing any possibility of contamination during preparation, as a consequence of the elimination of steps and containers used for preparing and administering this kind of medicines, the operation being carried out completely inside the syringe, in a single step. 
     The invention also affords a quick operation since preparation and application times are shortened, assuring at the same time the exact dosage of the drug. It also avoids accidental cuts on the user&#39;s fingers since powdered drug and solvent glass containers are not employed. 
     The above mentioned advantages are a result of the novel syringe of the invention, which has a main body defining two aligned and coaxial chambers, from which that closer to the needle contains the powdered drug, and the second is a hollow cylinder body tightly displacing through the inner part of the former chamber and including the liquid diluent. Further, through the interior of this second chamber, the syringe plunger displaces; between both chambers there is a elastomeric and tight plug, integral to the lower chamber body, tightly and slidably fitted on the inner cylindrical surface of the upper chamber body. This plug has a longitudinal central conduit communicating both chambers such that liquid contained in the lower chamber may penetrate the upper chamber when the syringe plunger is actuated, the mixture obtained is stirred until total dilution of the solid occurs; then injection is effected by continuously pushing the plunger which, at this time, also displaces said longitudinal central plug. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred, non-limiting, embodiment of the invention will be hereinbelow described in connection with the accompanying drawings, in which: 
     FIG. 1 is a schematic exploded perspective view of a syringe of the invention. 
     FIG. 2 is a schematic longitudinal section of the syringe of FIG. 1, showing the arrangement of the forming elements before use. 
     FIG. 3 is a section similar to that of FIG. 2 showing the arrangement of the forming elements once the product mixture (solid-diluent) is produced. 
     FIG. 4 is a longitudinal section as those of former figures, in this case with the needle removed after application. 
     FIG. 5 is a longitudinal view showing the way in which the two main portions of the syringe of the invention are separated and disabled. 
     In all figures, the same reference numerals designate the same or equivalent elements. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown by the drawings, the syringe of the invention is comprised by a first chamber body 1, a second, slidable, chamber body 2, a thrust plunger 3, an injection needle 4 having its plugging cone 5 and its sheath 6; a needle cover skirt 7 slidable with respect to said chamber body 1. 
     The novelty of the invention resides in the use of two chambers 10 and 11 which allows the pre-filling of the disposable syringe with powdered drug and diluent. 
     In fact, as may be seen in FIG. 2, the syringe of the invention may be marketed with the medicine already contained therein, i.e. the solid drug (powder) D inside chamber 10 and the diluent liquid L inside chamber 11. 
     In order that the assembly may operate properly, the upper base of the chamber body 2 has a coupling head 8 wherein the elastomeric plug is press-fitted, such plug being tightly fitted in the cylindrical wall of the chamber body 1 thus, said plug 9 serves as supporting means for the chamber body 2 and plunger 3 and also as tight division for both chambers 10 and 11. 
     Said plug 9 as well as the coupling head 8 have corresponding coaxial conduits 12 and 13 for communicating both chambers, blocked by brittle sheet 14 when products D and L are housed into their corresponding chambers (FIG. 2), before being mixed and diluted to be injected. 
     Thus, the use, before injecting the drug, should displace plunger 3 until the compressed liquid L collapses the separating sheet 14 at the portion between the two coaxial conduits 12 and 13. Said plunger 3 should displace until is head 15 abuts the upper base of chamber 2, whereby leak or feedback of mixture M contained in the body 1 is prevented, as shown in FIG. 3. 
     Once the mixture is at said body 1, the user stirs the syringe until the solid drug is wholly diluted. Then, the user may conventional inject the medicine, i.e. displacing plunger 3 along with the chamber body 2, the elastomeric plug 9 acting as pushing head, as may be seen in FIG. 3. 
     The disposable character of the syringe of the invention may be clearly seen in FIGS. 4 and 5. It is also to be noted that, due to the needle cover 7, the user does not contact the needle or its surroundings. 
     Regarding the constructive structure of plug 9 and brittle sheet 14, both have been selected as an example to be used in the present embodiment, but equivalent alternatives may be used for the same function.