DRUG DELIVERY DEVICE

Abstract: A drug delivery device comprising a cylinder (3) having a head portion forming a drug delivery member (2) for delivering a drug into a cavity of the body, a plunger (5) slidable within the cylinder (3) and having a front projection (4) adapted to advance into the drug delivery member (2), and a cap (1) adapted to cover the drug delivery member (2). The drug delivery member (2) is provided with drug delivery orifices (7) in its side wall towards its front end and the cap (1) is provided with an annular projection (9) on its inner side wall, the annular projection (9) being adapted to sealingly engage the outer side wall of the drug delivery member (2).

Description: This invention relates to a drug delivery device for administration of a fluid medicament such as a gel-form medicament into a cavity of the body, as specified in the preamble of claim 1, for example as disclosed in EP-A-0 139 855. The EP-A-0 139 855 shows a drug delivery device comprising a cylinder having a head portion forming a drug delivery member adapted to be inserted into a cavity of the body, a plunger slidable within said cylinder, and a cover-foil. The leakage of the content of the drug delivery device is prevented by an adhesive foil, which is torn off when the drug delivery device is used. Due to this, the danger of irritation of the anus exists which can be caused by a residue of the adhesive. It is the object of the invention to provide a drug delivery device according to the preamble of claim 1 which is adapted to be used without causing irritations. This object is achieved by the features in the characterizing part of claim 1. According to the invention the drug delivery device comprises a cap having an annular projection so that an intermediate annular space is formed when the cap is fitted on the delivery member. This annular space is filled with the drug which also fills the delivery member. The cap can be loosely fitted on the drug delivery member (the loose fitting permits air to be evacuated from the annular space as it fills with the drug). The plunger is then advanced so that the drug from the delivery member oozes through the orifices. Due to the positioning of the orifices on the sides of the drug delivery member, this does not cause the cap to be lifted off from the drug delivery member due to the resulting dynamic fluid pressure. The drug is retained in the annular space which is perfectly sealed when the cap is subsequently tightened onto the drug delivery member. It is therefore possible to provide a fluid coating as a lubricant on the outer surface of the drug delivery member without the need to apply a separate lubricating fluid. An embodiment of this invention will be described in detail hereinafter with reference to the accompanying drawings. It should be understood that, in this specification, the upward direction and the downward direction as viewed in Fig. 1 will be referred to as front and rear, respectively. Fig. 1 is a longitudinal section view showing a drug delivery device according to this invention prior to assembly. The device comprises a cap 1, a cylinder 3 having a drug delivery member 2, and a plunger 5 having a front central projection 4 adapted to fit into said delivery member 2 and having a piston 6 disposed in a rear portion thereof. The drug delivery member 2 is formed by one-piece molding with the cylinder 3 at its head. The drug delivery member 2 is tapered towards its front end and, as shown in Fig. 2, the side wall thereof is provided with three drug delivery orifices 7. The base of the cylinder 3 is provided with a finger-rest 8 on which fingers can be set in using the device. The cap 1 is so designed that when it is positioned over the delivery member 2 and a collar 1a formed at its base abuts a shoulder 3a of the cylinder 3, an annular projection 9 formed in the center of the side wall of the cap 1 comes into sealing contact with the outer side wall of the delivery member 2. The plunger 5 comprises a couple of disks and when the front face of the plunger 5 abuts the inner wall of the shoulder 3a of said cylinder, the projection 4 formed centrally in the front of the plunger 5 occupies substantially the whole cavity within the delivery member 2. Further, as illustrated in Fig. 3, a piston 6 having a cruciform section is one-piece molded with the plunger 5 at its back and a finger-rest 10 on which fingers may be set in using the device is one-piece molded with the rear end of the piston 6. An exemplary mode of use of the above drug delivery device is described hereinafter. First, the cap 1 is loosely set over the drug delivery member 2 and a predetermined amount of a gel-form medicament M is filled into the delivery member 2 and cylinder 3. Then, the plunger 5 is advanced into the medicament M in the cylinder 3 until the plunger has reached the rear end of the cylinder 3. Thereupon, a portion of the medicament M oozes out from the delivery orifices 7 but it is retained in a space R defined by the inner side wall of the cap 1 and the outer side wall of the delivery member 2 forwardly of the annular projection 9 of the cap 1. Then, as the cap 1 is tightened until the collar 1a of the cap 1 abuts the outer wall of the shoulder 3a of the cylinder, the annular projection 9 comes into sealing contact with the outer side wall of the delivery member 2 and the medicament M oozing out from the delivery orifices 7 spread evenly into the space R. The drug delivery device thus filled with the medicament M (Fig. 4) is preferably sealed tight, for example by shrink packaging. To administer the drug, the drug delivery member 2 is inserted into the cavity of the body such as the anus and, then, the finger-rest 10 is pressed forward just as in the case of the ordinary drug delivery device, whereby the medicament M is delivered into the cavity of the body from the delivery orifices 7. For example, the size of the cylinder may be freely selected in view of the amount of a medicament to be filled therein and the length and shape of the delivery member may be fitted to the body cavity into which the device is inserted. The number of drug delivery orifices is optional and the piston may be rod-shaped. The drug delivery member may be a cylindrical member without a taper and the projection to be advanced into it may likewise be a columnar member with a diameter slightly smaller than the inner diameter of the cylindrical member. Furthermore, as shown in Japanese Design Registration No. 669,474, it may be so arranged that the cap is affixed to the rear wall of the plunger so as to serve as a piston. As the drug delivery device according to this invention is such that drug delivery orifices are formed in the side wall towards the tip of a drug delivery member, the drug is not propelled too far into the cavity of the body but retained in the cavity at the site of administration even if the piston is pushed with a force in use, so that the efficacy of the drug may be assured with certainty. Moreover, this device can be easily inserted into a cavity of the body because the drug delivery end is smoothened by the drug retained between the outer wall of the delivery member and the inner wall of the cap forwardly of the annular projection provided on the inner side wall of the cap. Brief Description of the Drawing Figures 1 to 4 show an embodiment of this invention; Fig. 1 is a longitudinal section view of the same prior to assembly, Fig. 2 is a plan view showing the delivery member and cylinder, Fig. 3 is a transverse section view taken along the line III-III of Fig. 1, and Fig. 4 is a longitudinal section view showing the device filled with a drug. (1)---cap, (2)---drug delivery member, (3)---cylinder, (4)---projection, (5)---plunger, (6)---piston, (7)---drug delivery orifices, (9)---annular projection

Claims: A drug delivery device comprising: a cylinder (3) having a large diameter; a drug delivery member (2) comprising a hollow elongate element coaxially fitted to one end of said cylinder (3) and in fluid communication therewith so as to form a head portion for delivering a drug, said drug delivery member (2) having a diameter substantially smaller than that of said cylinder (3) and being filled with a drug; drug delivery orifices (7) only in a side wall of said hollow elongate element at an end thereof opposite said cylinder (3); a plunger (5) fittable into an end of said cylinder (3) opposite said drug delivery member (2), said plunger (5) having a disc portion comprising means for advancing a drug in said cylinder (3) towards said drug delivery member (2) as said plunger (5) is advanced toward said drug delivery member (2), said plunger (5) also having a central projection (4) which fits into said drug delivery member (2) when said plunger (5) is advanced, said central projection (4) and drug delivery member (2) being shaped such that a drug in said hollow cylinder is permitted to flow into said drug delivery member (2) when said central projection (4) is fitted into said drug delivery member (2) as said plunger (5) is advanced, characterized in that a cap (1) is shaped to cover said drug delivery member (2), said cap (1) having an annular projection (9) on an inner side wall thereof, said annular projection (9) sealingly engaging the side wall of said hollow elongate element when said cap (1) is fitted on said drug delivery member (2) to define an annular space (R) evenly filled with said drug, said cap (1) comprising means for leaving said orifices (7) open when said cap (1) is fitted on said drug delivery member (2), whereby said drug may be caused to fill said annular space (R) by advancing said plunger (5) while said cap (1) is fitted on said drug delivery member (2).

Inventors: NAKATA, KEIKO, OHTOMO, KAZUMI, OKADA, KIYONORI, OKUDA, KIYOSHI
Applicants: FUJISAWA PHARMACEUTICAL CO., LTD.
Application year: 1987
Main classification: A61M31
IPC codes: A61M5, A61M3, A61M31