Coating processes – Medical or dental purpose product; parts; subcombinations;... – Particulate or unit-dosage-article base
Reexamination Certificate
1999-07-02
2003-12-16
Beck, Shrive P. (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Particulate or unit-dosage-article base
C427S002100, C427S212000, C427S213300, C427S213310, C427S213350, C427S214000, C427S355000, C427S356000, C118S035000, C118S036000, C118S040000
Reexamination Certificate
active
06663913
ABSTRACT:
INTRODUCTION
This invention relates to apparatus and methods for coating a material. As will become apparent from the following description, the invention can be used in many coating applications, however one application to which the invention is particularly suited is in relation to the production of coatings for pharmaceutical capsules, tablets and like devices for the delivery of pharmacologically active substances (for either human or veterinary use) to a patient. The invention is especially suited for use in the production of pharmaceutical capsules, tablets and like delivery devices where the coating material for the pharmaceutical delivery device is intended to control or delay the timing of release of a pharmacologically active material contained within the “core” of the device. While noting the invention's suitability in a broad range of applications, it will be described in the following description with particular reference to the pharmaceutical coating application to which it is particularly suited.
BACKGROUND TO THE INVENTION
In order for an effective dosage regimen to be delivered, many pharmaceutical substances must be administered according to exacting or occasionally, complex dosage regimes. Compliance with such regimes is particularly important in, for example, many third world countries, where patient compliance with a dosage regimen may be impaired due to the patient's inability to understand the nature of the dosage regimen required, or the need for compliance. Similarly, the treatment of infants by a repeated course of injections can be particularly traumatic to the infant patients concerned, and the delivery of the regimen by a reduced number of doses whose release profile is controlled is particularly desirable. Another important scenario where controlled release delivery can be particularly advantageous (compared to repeated application of individual doses) is in veterinary medicine. Many animals react extremely adversely to the infliction of pain by (for example) repeated injections. In the veterinary treatment of animals, it can be particularly difficult to ensure that the animal has received the dosage required of the pharmaceutical agent concerned (particularly, for example, if the pharmaceutical agent involved must be administered in minute quantities, such as, for instance, with reproductive hormones used in animal husbandry). Repeated handling of an animal to administer drugs to it not only runs the risk that the animal will refuse to co-operate with the handler, and that the required dose of the drug may not in fact be delivered, but also, it runs the increased risk of injury to the animal handler that must administer the drugs.
The use of controlled release pharmaceutical delivery devices is therefore particularly desirable in many instances, including those described above. However, the delivery of drugs via controlled release regimens is not as widespread as might be hoped, because the production of suitable delivery devices for the controlled release of pharmacologically active substances is presently limited by the manufacturing methods 3 and production apparatus that have been used to date to make them.
Several methods have been employed to date in order to manufacture controlled release delivery devices to contain a dose of a pharmaceutical agent in the form of (for example) a tablet. One method that has been employed is injection moulding. This technique involves the injection of a heated coating material (typically, a pharmaceutically acceptable polymer) under pressure into a mould for a delivery device (in the form of, for example, part of a container). Once the coating material has cooled and solidified to a suitable extent, the mould is opened for ejection. The part container must then be filled with the pharmaceutical agent it is intended to contain, and it must then be sealed. This technique has significant limitations, particularly for the mass production of controlled release pharmaceutical delivery devices. For one thing, as explained above, it results in the production of only a partial container. This means that the process of producing a controlled release drug delivery device via the injection moulding method is a multi-step procedure, which requires sequentially (i) first, the production of a partial container, (ii) filling the partial container with the required dose of the drug it is intended to contain, and (iii) then sealing the container. This sequential, multi-step procedure is inefficient as a manufacturing process. It also involves a time delay between the initial step of manufacturing the partial-container and the subsequent steps of filling it with the pharmaceutical moiety and sealing the container, which can give rise to difficulties as regards ensuring that the finished product is sufficiently sterile for use in human or veterinary medicine.
A second technique is available for manufacturing pharmaceutical delivery devices in such a way as to overcome the sterility problems described earlier that affect the injection moulding procedure. In the pharmaceutical context, to date, the second technique appears to have been used solely in the manufacture of sterile vessels to contain liquids like physiological saline or water for injection. This second technique is referred to in the art as the “blow-fill-seal” (or the “form-fill-seal”) method. In this technique, a polymer (usually a plastics material) is melt-processed and extruded from a die to form a length of tube. When extruded, the tube is sufficiently hot to be malleable, but not so hot as to be liquid, and therefore, so as to be uncontrollable in the subsequent steps involved in the manufacturing process. A multi-piece die (containing a mould which encompasses the length of extrudate) then clamps around the length of extrudate (which is known as the “parison”), thereby sealing one end of the parison, and leaving the other end gripped by the die, but slightly open. The parison (which at this stage of the process, remains hot and malleable) is a thin tube which is suspended within the mould cavity. Air is then injected into the interior of the parison so as to inflate it, so that it assumes the shape of the mould. The inflated parison is then filled with the desired contents by an injection process, and is then sealed. The die is then opened to release the finished product. The “blow-fill-seal” technique is similar in many respects to injection moulding. It is therefore subject to at least some of the same problems that apply to the injection moulding technique.
The present invention aims to avoid one or more difficulties associated with the prior art manufacturing techniques described above, and the apparatus used to perform them.
GENERAL DISCLOSURE OF THE INVENTION
The invention generally provides a method of coating a material, the method including the following steps:
(a) forming a generally elongate coating structure, the coating structure having an internal cavity extending at least substantially along its length, and wherein the internal cavity of the coating structure is capable of receiving a core material;
(b) inserting a core material into the internal cavity of the coating structure;
(c) compressing the coating structure at a first location along its length so as generally to form a seal at that location; and
(d) compressing the coating structure at a second location along its length.
The method may be performed sequentially in the order of steps (a) to (d) set out above, or the steps of the method may be performed in another sequence. A preferred sequence is (from first to last step):
Step (a) (first step)
Step (c) (second step)
Step (b) (third step)
Step (d) (fourth step).
Preferably, the step of forming the coating structure involves extruding it from an extrusion means. In this embodiment of the invention, the coating structure must be an extrudable material, such as a plastics material which is amenable to processing techniques such as melt-processing and extrusion when heated. The extrusion means could for example, take the form of a
Morris James Allan
O'Donoghue Michael Francis
Beck Shrive P.
Kolb Michener Jennifer
Roylance, Abrams, Berdo & Goodman LLP.
Scientec Research Pty. Ltd.
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