Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Utility Patent
1999-03-19
2001-01-02
Azpuru, Carlos A. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S424000, C424S425000
Utility Patent
active
06168801
ABSTRACT:
TECHNICAL FIELD
The present invention relates to natural and synthetic polymeric articles having chemical, biological, medicinal and/or physical or other active properties or combinations of properties. The invention also relates to methods for preparing such articles and delivering medication with such articles.
More specifically, the invention relates to body-implantable polymeric articles having active medicinal properties.
BACKGROUND
It is known in the art that active properties can be imparted to polymeric articles by a variety of methods. One common method is to incorporate one or more activating agents into the polymeric compound during the mixing or blending phase prior to processing or manufacturing the article. Activation is accomplished by thoroughly distributing the activating agents throughout the compounding ingredients. For example, synthetic thermoplastics, natural and synthetic rubbers and other polymeric materials have been blended with activating agents such as antibacterial, antistatic, electrically conductive and other chemically or physically active agents. The activated polymeric materials are then formed into sheets, fibers, rods or other configurations by molding, casting, extruding, calendering and/or other manufacturing or processing operations.
A second method widely used to impart certain active properties to the exposed or working surface is to apply a compound containing active agents to that surface. For example, anti-fouling marine paints, antifungal sprays and coatings, fire-resistant coatings and antistatic coatings have been applied to the surface of the article. The activity of such coating is superficially “skin deep” and surface activity is lost to the extent that the activated coating peels or is mechanically abraded, chipped or washed away from the inactive substrate. While this method affords certain flexibility in providing an activated surface, it is at best subject to severe limitations of available range of active ingredients that can be applied in this manner plus limited service life and efficiency.
Another method for the production of activated articles is to expose the article to the vapors of a volatilized chemical. This ancient technique has long been applied to textiles, polymer sheets, or the like and comprises vaporizing a volatile agent, usually a biologically active agent, and then exposing the textile or other article to the vapors. A major disadvantage of this method, however, is that it requires special buildings, ventilation and recovery equipment, and safety procedures. Since the active agent has a volatilization temperature which necessarily is much lower than the melting point of the article to which the activating vapors are applied, the activation may be readily lost where the article is exposed to elevated temperatures. Thus, the treated material may be rapidly deactivated when subjected to wet or dry heat, for example, by exposure to steam sterilization or other high temperature washing procedure, intense sunlight etc.
The use of controlled release implants for administering estradiol to ruminant animals has been described in U.S. Pat. No. 4,191,741. During implantation of such implants, conditions may be unsanitary, causing infections which could lead to loss of the implant. Use of an antibiotic or germicide layer, or a coating on the surface of the implant to reduce infections and to improve implant retention has been described in U.K. Patent No. 2 136 688 A. There an antibiotic coating facilitates parenteral administration of the implants under non-sterile conditions. Requirements for cleaning any implant needle, the site of implantation, and the implantation itself are minimized or reduced. Other infection-resistant implant materials have been described in the art, such as in U.S. Pat. No. 4,581,028 which describes infection-resistant materials suitable for use as vascular graft prostheses or other implanted devices.
It is known that antimicrobial agents can be layered or coated onto the surface of an implant to inhibit infection at the site of implantation. However, some difficulties have been encountered in implementing that technology. Surface-applied antimicrobial agents have been found to be easily dislocated from the surface of the implant by nominal mechanical activity on the implants, including during packaging. Loss of antimicrobial coating reduces the activity of the treatment significantly. Coating uniformity may also be difficult to control.
U.S. Pat. No. 3,857,934 provides a method for activating nonporous polymeric articles by applying the activating agents to one surface of the article so that the agents migrate throughout the body of the article and impart an effective level of activity throughout the article and on surfaces to which the activating agent has not been applied. The articles made by this method comprise an active layer which is applied on one surface of the article, and which contains an active migrating agent. The concentration of the agent is in excess of the concentration needed to provide an effective level of activity in the layer, and is sufficient, upon migration of the agent from the layer, to impart an effective level of activity throughout the entire article. The high concentration of the active migrating agent in the layer also provides a reservoir of activating material capable of replenishing the effective surface activity of the article.
The methods and products of U.S. Pat. No. 3,857,934 do not require extreme processing conditions so that volatile activating agents are conveniently used at normal temperatures; toxic agents can be handled safely; and a wide variety of inactive polymers can be given almost any desired activation. Only stocks of inactive articles are needed and the desired activation may be applied when desired. The activated article has long-lasting properties which persist even if a surface layer is removed and which are replenished from thc reservoir of activating agent contained within the active layer.
U.S. Pat. No. 4,819,662 describes a device and a process for providing medical activity through introduced chemistry in a cardiac electrode. The invention comprises an implantable cardiac pacing lead including a porous platinum electrode, a flexible electrically conductive coil, and a crimp tube coupling the electrode to the distal end of the coil. There is a recess in the crimp tube, open to the electrode at the crimp distal tube end, which houses a matrix impregnated with a therapeutic drug. The electrode is highly porous and may be loaded with a therapeutic drug in liquid or solid form. The drug, because of its porous exposure to the environment, is immediately released upon implantation of the cardiac pacing device. A variety of different matrices carrying therapeutic drugs may be housed in the recess to provide elution of different drugs and at different rates.
U.S. Pat. No. 4,846,844 describes an improved antimicrobial implant coating comprising a silicone fluid in contact with the surface of the implant and a microbial agent in contact with the silicone fluid. The silicone fluid may be first applied to the implant and the antimicrobial agent may be applied to the fluid, for example as a dust applied to the liquid coating. The effectiveness of the application is asserted to derive from the high affinity of the silicone fluid to both the implant surface and to the antimicrobial agent.
SUMMARY
A material is described for delivering a chemically active, biologically active or medically active compound. The material comprises a solid carrier having at least two active compounds dissolved and/or dispersed therein. Each of the at least two active compounds are medically or biologically active compounds. Each of the at least two active compounds have an active nucleus which is common to each of the active compounds. The at least two active compounds also have maximum solubility levels in a single solvent which differ from each other. In one embodiment, the maximum solubility level of a first active compound in the solvent exceeds the maximum so
Heil, Jr. Ronald W.
KenKnight Bruce H.
Azpuru Carlos A.
Cardiac Pacemakers Inc.
Schwegman Lundberg Woessner & Kluth P.A.
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