METHOD FOR MANUFACTURING OF SUBCUTANEOUS CAPSULES

Abstract: The invention relates to a method for manufacturing subcutaneous capsules. The capsules are produced by cutting from a silicone tube lengths in excess of the final capsule length. The lenghts are arranged into rows including a defined number of them and in these rows they are filled and sealed. One end of the capsules is first sealed by glue dosaged into their openings. The material for the capsules is dosaged by an aperture disc glidable on a plane surface. By sweeping the upper surface of the disc the dosage volume is limited to the volume defined by the aperture. To regulate the packaging density of the material vibration may be used during the filling of the apertures. The dosaged material is conveyed to the capsule via a feeder funnel, through which a rotatable spiral spring, functioning as a filling screw, is inserted into the capsule to be filled.

Description: Method for manufacturing of subcutaneous capsules The present invention relates to a method for manufactu- ring of capsules filled with a medical substance essen¬ tially in powder form, which capsules are intended to be implanted under the skin and from which the medical subs¬ tance will diffuse into the blood circulation through the wall material of the capsules. Intended uses are i.a. dosage of hormones, especially contraceptive hormones as well as of antabus agents. A problem in the dosage of contraceptive hormones has been above all the small amount of the hormone substance to be portioned accurately in powder form into the small- sized capsules. The amount of substance diffusing from the capsule is proportional to the amount of substance in the capsule and therefore, to assure a correct and in all cases a truly predictable liberation, the capsules should include exactly the same amount of substance. In the said hormonal use, the tolerances allowed are ± 5%, which accuracy is extremely difficult to reach with the prior used manual dosing. The manual dosing method is, natural¬ ly, also a very expensive stage in the production of the capsules because of the great need of human workforce. The invention relates to providing a totally automatic manufacturing process for subcutaneous capsules filled with a medical substance, whereby the uniformity of the end result is essentially better than that of correspon¬ ding prior art processes, involving partly manual stages. In capsule production the starting point is a tube for forming the casing of the capsule, and for which a suit- able material is a silicone plastic. The diameter of the tube for manufacturing of hormone capsules is 1.5 mm. The tube is fed to the capsule manufacturing line as conti¬ nuous lengths from a suitable apparatus. At the starting point of the capsule manufacturing line, the tube is cut into capsule blanks of a suitable length, e.g. to lengtns of about 34 mm. The said blanks are then arranged into a row formed by several blanks. One row may comprise e.g. 12 blanks. The position of the blanks is advantageously chosen in con¬ formity with the handling positions of the tube in the preceeding cutting device. One of such rows is advanta- geously joined together and it will then form a handling unit for the next process stages. In order to assemble this handling unit row it is possible to use a means to keep the blanks in their prescribed positions and with the help of which the handling unit row is transferred from one stage to another in the process, as well as positioned for each process stage. The said means can advantageously be a cassette of a clamping claw structure where the claws are in a mutual spring loaded clamping contact and where mutually co-operating indentation slots have been formed on the contact faces of the claws in order to form through holes for receiving the capsule blanks. The claws are made to retract from each other against the said spring load to receive the capsule blanks. The operation of the said cassette is advanta- geously synchronized with the capsule blank cutting devi¬ ce. To make the capsule blank fillable, one of its ends has to be sealed. In the apparatus according to the applica- tion, this stage is carried out so that one end of the tubes forming the capsule blanks receives a small amount of glue, e.g. a silicone glue, that adheres well to the tube material forming the capsule wall. The glueing is carried out by using a very thin nozzle needle inserted to a depth of about 1.6 mm in the capsule blank. The glue is discharged from the nozzle simultaneuously when the nozzle needle is rotated and extracted. By adjusting the speed by which the nozzle needle is extracted it is pos¬ sible to regulate the amount of glue remaining in the capsule blank. This possibility is utilized in the pro¬ cess according to the application to eliminate the i - pacts of the viscosity fluctuations of the glue, by moni¬ toring the load on the glue pump and regulating the speed by which the nozzle needle is extracted in relation to the load. A high viscosity glue, discharged slowly from the needle, will load the dosing pump more than a low viscosity glue. Whenever the load on the dosing pump is rising, the speed by which the needle is extracted is slowed down. The glue fed to the end of the capsule blank i_ hardened by a suitable accelerator, e.g. using humidity or hea¬ ting. After the hardening of the glue there is the possi¬ bility, whenever desired, to use a finishing treatment of the sealed end by cutting out a part of the end of the capsule blank, from the area sealed by glueing. After sealing the capsule blanks, the blank row is turned- so that the ends still left open are facing upwards. In this position the capsule blanks are forwarded to the filling stage. The filling stage involves as an essential element the dosing of the mass of material to be fed into the capsu¬ le blank. In the process according to the application, a device is used in which the dosing is based on a disc glidable along a plane surface and having through apertu- res determining the dose quantities. The material to be dosed is fed to the apertures closed by the lower plane surface, and the correct quantity is finalized by sweep¬ ing any extra material away at the respective apertures to the upper surface level of the disc. The quantities thus dosed are delivered, individually to each capsule blank, by moving the disc along the plane surface to such a position where the lower surfaces of the apertures will be freed . In the process according to the application the dosed quantity of material are dropped from each aperture to its respective transportation groove made in the surface of a disc, operating as a vibrating conveyor. When the apertures are emptied the dosing disc is transferred back to its filling position. The dosed material quantities proceed in the grooves of the vibrating conveyor further to feeding funnels under which the capsule blanks, car¬ ried by the clamping claw cassette, have been conveyed. In order to promote the flow of the material quantities into the capsule blanks, a special spiral feeder is used. he said feeder comprises a spiral spring that has a diameter less than the inner diameter of the capsule blank, and a straight steering wire therein. This spring is rotatable in the forward direction of its spiral. As far as the feeding process itself is concerned, the procedure is carried out so that the spiral spring is inserted into the capsule blank and made to rotate. Si¬ multaneously with the activation of the rotative movement the raising of the spiral spring from the capsule blank is initiated. When the rotation direction is as said above, the spring acts as a feeder screw. When the fil¬ ling of the capsule blank advances, the spiral spring is extracted, still in rotation, from the capsule blank. During the said operational stages the feeding funnels are kept under vibration. When the head of the spiral spring has risen to the desired material filling level its rising movement is stopped, but vibration, and rota¬ tion of the spring are continued. Thus, the spiral spring determines the height of the material column fed to the capsule. After the filling stage, it is advisable to clean the inner surfaces of the open ends of the capsule blanks to remove any adhered filling material to ensure the closing of the ends of the capsule blanks without problems. The cleaning may be carried out on the inside of the mouth area of the capsule blank by using a scraping rotating mandrel or a corresponding brush. The ends of the capsule blanks are sealed by using similar procedures as in con¬ nection with the above described sealing of the first ends of the capsule blanks. After the glue used in the sealing process has hardened, the capsule ends may be similarly finished by cutting parts away from their seal¬ ed portions. After these stages the completed capsules are conveyed through as such known process stεges, whereby the capsu- les are washed, dried, inspected, packaged and sterilized to ready-to-use products. In the following, the invention will be described refer¬ ring to the annexed drawing where: Fig. 1 shows a flow chart of the process according tc the application in principle; Fig. 2 shows an embodiment of an apparatus in princi- pie for cutting the capsule blanks and their arrange¬ ment in handling unit rows; Fig. 3 shows a dosing and filling apparatus seen in the forward direction of the process; Fig. 4 shows a dosing and filling apparatus seen from above; Fig. 5 shows a dosing and filling apparatus seen frorr. the side with respect to the forward direction of the process; Fig. 6 shows a dosing and filling apparatus axonomet- rically; Fig. 7 shows a simplified flow chart according to Fig. 6, and Fig. 8 shows a magnified detail from the area of the feeding funnels. In the basic flow chart according to Fig. 1 the process stages are shown in the advancing order principally as described ' above. The first stage of the process, i.e. the cutting cf the capsule blanks and their arrangement to rows forming the handling unit, is described in more detail in the draw¬ ing Fig. 2. The silicone tube 1 forming the casing of the capsule blanks.is fed as a continuous length from a coil, guided by two feeder rolls 2, to an aperture made in a disc 3 rotatable around a vertical axle. The aperture is a through hole and its diameter is designed to match the outer diameter of the tube so that the cut tube will stay in the aperture without any separate supporting means, partly due to the distortion tendency caused by the mate¬ rial memory of the tube. In connection with the tube feeding station there is a cutter device 4 by which the tube is cut to the upper surface level of the disc. The length of the capsule blank to be cut may be determined by the duration of the rotation movement of the feeder discs 2. By rotating the disc around its vertical axle, it is possible to move the capsule blank, formed by the cut tube, to a discharge station where the capsule blank is taken from its aperture by a punch-through mandrel 5. From the point-of-view of the flexible operation of the apparatus, it is advantageous to have several through apertures in the disc 3 whereby the cutting of a new blank and the discharging of the previous blank may be carried out as simultaneous operations. The operation of the cutting device is advantageously synchronized with the device arranging the cut capsule blanks. As such a device arranging the capsule blanks it is advantageous to use a spring-loaded clamping claw cassette 6 consisting of two opposite co-operating halves 6' and 6' ' . The halves are separated from each other by a vertical dividing plane, the separating surfaces being furnished with essentially semicircular opposite grooves traversing the dividing plane that, when operating toget¬ her, form the through apertures 8 receiving the capsule blanks 7. The apertures 8 have been placed at an even distance from each other, and the clamping claw cassette 6 has been arranged to be moved stepwise with steps of respective length in the direction of the row of apertu¬ res to receive the capsule blanks 7 coming from the cut¬ ting device. To facilitate the reception of individual capsule blanks 7 from the cutting device, the clamping claw cassette 6 has been arranged to be opened, to a limited extent, for each receiving operation. This opening capability has been provided for by using two wedges 9, acting in the division plane at the ends of the cassette, which wedges can be pushed towards each other in the division plane. By means of these wedges, the clamping claw cassette 6 halves may be retracted from each other against the springloaded (not shown) force pressing them against each other. The springload may be provided for, e.g. in con¬ nection with screw joints joining the clamping claw cas¬ sette halves, by spring washers or similar devices, as the opening movement does not need to be very big in relation to the diameter of the capsule blank. Deviating from the embodiment shown in the drawing figu- res 1 and 2, the disc 3 of the cutting device may also be arranged to rotate around a horizontal axle and, respec¬ tively, the clamping claw cassette 6 arranged to receive the cut capsule blanks in horizontal positions. The capsule blanks are conveyed, carried by the said clamping claw cassette 6, to the next processing stages and through them, of which a general description con¬ cerning the sealing of the second ends and their trim¬ ming has been given above. These operations may be car- ried out when the capsule blanks are either in a vertical position, as shown in Fig. 1, or alternatively, in a horizo tal position. An alternative trimming of the ends may also be combined with the trimming following the sealing of the filling end, to be described later, to a single stage only. As an important partial stage in the process, the dosing of the material to be packaged into the capsules is desc¬ ribed, as well as the equipment relating thereto, refer- ring to the drawing figures 3 to 8. The said equipment is used to dosage the material for each capsule blank and to direct it to the respective capsule along its own path. The dosing equipment is based on the so-called aperture disc technology, whereby the material mass is dosed by the means of a plate of even thickness movable on a plane surface and provided with through apertures defining the dosage quantities. When the dosage quantities are mete- red, the disc lies on the said plane surface and the plane surface closes the bottom part of the apertures. The material to be dosed is made to flow into the apertu¬ res and the exact dose volume is determined by sweeping the excessively fed heap of material away, to the upper surface level of the disc. Then the disc is moved along the said plane surface to a discharging station, where the lower surface of the apertures is opened to a recep- tacle for the material. In the device according to Fig. 3, the material used for filling the dosage apertures is fed from a storage con¬ tainer 10 by means of a compartment feeder 11, performing a rough dosing, to a trough-like vibrating conveyor 12. This vibrating conveyor transfers the material to be dosed further to distribution through 13 at a lower le¬ vel, the open lower part of which is defined by the do¬ sing disc 14. The dosing disc 14 is glidable on the plane surface 15. The number of through apertures in the dosing disc 14 in the described embodiment is half of that of the capsule blanks to be filled in the clamping claw cassette 6. The parts of the device may naturally also be dimensioned so that the number of the apertures and the number of the capsule blanks to be filled are the same. The diameter of the apertures 16 is dimensioned so, ta¬ king the thickness of the aperture disc 14 into account, that the apertures, when filled up to the upper surface of the disc, will define the volume of the dose intended for each capsule, or so that a dosage volume is formed by a multiple of aperture fillings. In the device described in the drawing figures 3, 4, and 5 the material to be dosed and transported by the vibra- ting conveyor 12 is spread into the distribution through 13 by means of a device movable by a cylinder-piston device 18. An optical control device 19 is arranged above the through 13, by means of which the surface level in the distribution through 13 of the material to be dosed is monitored, and on the basis of the information of which the number of operation cycles of the compartment feeder 11, which functions as a rough dosing device, iε determined. The plane surface 15, on which the dosing aperture disc 14 is glidable and upon which it rests during filling of the dosing apertures, is combined with a suitable vib¬ rating device in order to direct a vibrating effect on the plane surface during the filling stage of the apertu¬ res 16. This vibrating effect will act on the packaging density of the material to be filled into the dosing apertures 16. It is possible to regulate the packaging degree by regulating the duration and/or the intensity of the vibration. Another factor influencing the packaging degree is the filling level in the distribution through 13 of the material to be filled monitored by the said optical control device 19. After the filling of the apertures, the dosing disc 14 is pushed along the plane surface 15 to the discharge sta¬ tion of the apertures. The upper surface of the dosing disc 14 is in gliding contact with the lower surface of the distribution through 13 whereby the lower edge of the through levels the dose quantities in the apertures to the upper surface level of the dosing disc 14, whereby the excess material remains in the distribution through 13 closed by the dosing disc 14. In the level surface 15 there is formed a row of dischar¬ ge apertures 20 corresponding to the dosing apertures 16, above which row the apertures 16 are glided. Arranged below the discharging apertures 20, there is a vibrating conveyor formed by a groove disc 21. In the groove disc 21 there is the same number of grooves 22 as there are discharging apertures 20, and the grooves and the dis¬ charging apertures are aligned so that the material in the dosing apertures can be discharged through the dis¬ charging apertures 20 to their respective groove 22 in the groove disc 21. The groove disc 21 is preferably declining and equipped with a vibration device, whereby a groove 22 forms a conveyor for a single dosage. The dosaged material is transferred on the groove disc 21 to filling funnels 23 arranged in a transverse row be¬ neath the f il edge of the groove disc 21. Below these filling funnels there has in turn been transferred a row of capsule blanks 7 carried by the clamping claw cassette 6, the lower ends of the capsule blanks having been sea- led and advantageously trimmed according to the measures described above. The equipment according .to the figures 3 to 8 also comp¬ rises a filling apparatus 24, comprising a number of feeding devices corresponding to the number of filling funnels 23. Each feeding device comprises a rotating motor 25, a spindle 26, and a feeder screw 27 attached to the the lower end of the spindle. To operate the feeder screw 27 within the conditions determined by the small dimensions of the capsules to be filled, the filling screw is formed by a thin spiral spring. For better cont¬ rol of the movements of the spiral spring, a thin straight guiding wire is placed inside the spring, extending substantially along the whole length of the spiral spring. The feeder screw 27 formed by the spiral spring is di¬ rected through each feeding funnel 23 to the capsule blank below it and is made to rotate. The rotative move- ment is naturally chosen in the feeding direction of the spiral spring. The feeder screw rotating in the capsule blank feeds the material fed into the feeder funnel effi¬ ciently into the capsule blank. In order to avoid unne¬ cessary compacting of the material in the capsule blank, the feeder screw is raised as filling is advancing. After the dosed batch has been completely fed, the feeder screw is removed completely from the capsule blank, and the blanks are transferred to be sealed. Before sealing, it is possible to clean the inside of their mouth areas to remove any remaining filling material. The sealing is carried out by glueing in the same way as the sealing of the opposite end of the blank before the filling stage. After sealing, the ends of the filled capsules can be trimmed by cutting. After trimming, the final capsules are removed from their respective clamping claw cassettes after which operation they will be processed individually according to prior technology discussed briefly above.

Claims: Claims 1. A method for manufacturing a subcutaneous capsule filled with a medical substance from a tube forming a capsule casing, whereby the tube is cut in fixed lengths, the fixed-length capsule blanks cut from the tube are arranged to rows including a defined number of capsule blanks, and by performing the following operations for one row at a time, in the order of advancement of the rows: one end of the capsule blanks is sealed; the medi¬ cal substance is dosed in separate doses for each capsule by means of an aperture disc glidable along a plane sur¬ face, by filling the apertures in the disc up to the upper surface level of the apertures in the discs, by transferring the disc to a discharge station and by- dropping the medical substance in the disc apertures to a respective feeder device, for each capsule blank; each capsule blank is filled by the medical substance received from the feeder means using a rotatable spiral means insertable into the capsule blank; and the filling end of each capsule blank is sealed. 2. A method according to the claim 1, wherein the upper ends of the capsule blanks are cleaned from medicine residues after the filling stage. 3. A method according to the claim 1, wherein the sealed ends of the capsule blanks are trimmed after the glue has hardened by cutting the blank end within the glued length. 4. A method for manufacturing a subcutaneous capsule filled with a medical substance from a tube forming a capsule casing, in which method a continuous length of the tube is fed periodically to a device cutting the tube in fixed lengths, the fixed-length capsule blanks cut from the tube are arranged vertically in their cutting order into rows having a standard number of capsule blanks, and by carrying out the following operations for one row at a time, in the order of the advancement of the row: one end of each capsule is sealed by feeding glue therein and by hardening the glue; the capsule blanks are turned to a position with the open end upwards; the medi¬ cal substance is dosed for each capsule using an aperture disc glidable on a plane surface by filling the apertures in the discs to their upper surface levels, by transfer- ring the disc to their discharging station and by let¬ ting the medicine in the disc apertures flow into a fee¬ der means, one for each respective capsule blank; each capsule blank is filled with the medical substance brought by the feeder means by using a rotatable spiral spring means insertable into the capsule blanks; the upper ends of the capsule.blanks are cleaned from medici¬ ne residues after the filling stage; and the open end of each capsule is sealed by feeding glue -therein and by hardening the glue.

Inventors: HARTZELL ROLF, HELLE TIMO, LANKINEN PEKKA, NIEMINEN PEKKA, HARTZELL, ROLF, HELLE, TIMO, LANKINEN, PEKKA, NIEMINEN, PEKKA
Applicants: HUHTAMAEKI OY
Application year: 1991
Main classification: A61J3
IPC codes: A61J3, A61M31