Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
1999-11-30
2003-06-17
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S422000, C424S423000, C424S601000, C424S602000, C424S489000, C424S484000, C424S078080
Reexamination Certificate
active
06579533
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods of preventing and treating infections. More specifically, it relates to the use of synthetic, bioabsorbable polymer-based composite materials and implants, like microspheres, membranes, capsules, shells, honeycombs, spheres, rods, screws, plates, suture anchors, tacks, and other fixation devices, which contain (a) a bioabsorbable polymer, copolymer or polymer alloy (“polymeric”) matrix, (b) an antibiotic or antibiotic mixture dispersed into the matrix and (c) a bioactive glass filler or reinforcement dispersed in the matrix, which bioactive glass phase promotes bone growth and possesses an antibacterial effect. Preferred embodiments of the materials and implants of the present invention provide a sustained release of antibiotic over several weeks or months for the prevention and/or treatment of infection and also can facilitate new bone formation, fracture healing, and/or endoprosthesis attachment. These implants may be effectively implanted into or on (1) an infected bone, (2) a possibly infected defect, void or fracture in bone tissue, or (3) a bone, bone defect, void, fracture or on an endoprosthesis of a patient who has a risk of developing an infection in the treated bone.
BACKGROUND
Virtually all surgical procedures create some type of void or dead space within the patient's body. This is particularly true in the case of surgery to remedy a localized infection. The infected area—an area of relative tissue ischemia—must be debrided and filled in. Further, antibiotics must be administered to prevent recurrence of infection in the void. Thus, the materials of the present invention will have beneficial application in many different types of surgeries.
One example is chronic bone infection (osteomyelitis). The standard therapy includes debridement and sequestrectomy of infected, dead bone, followed by several weeks of intravenous antibiotics. Unfortunately this treatment has several drawbacks. The multiple doses of antibiotics that are needed can become quite expensive. Also, the intravenous or GI tract administration of antibiotics does not allow the antibiotic to be specifically directed to the location of the infection. Further, intravenous administration of antibiotics requires an operation for placement of a catheter, which can lead to serious complications. Additionally, the removal of infected bone leaves a void or gap in the bone tissue. If the gap is large it rarely ossifies, instead filling with connective tissue which can lead, in the worst case, to an increased risk of bone fracture. Also in the case of bone fractures, especially severely comminuted, possibly infected fractures, the poor ossification of fractured bone can lead to non-union and/or to other complications. Similar problems of infections and poor bone formation can occur in the case of endoprosthesis attachment.
There are many different materials, devices and techniques for the local prevention and treatment of infections.
A well-known procedure for the treatment of bone infections is the use of polymethymethacrylate (PMMA) beads that contain antibiotics (e.g. Septobal® beads). Such beads are placed in surgical voids and thereby fill the voids, as well as providing local bactericidal levels of antibiotic. However, even these PMMA beads have disadvantages. First, they usually can only provide bactericidal levels of antibiotic for about a few weeks, so patenteral antibiotic must also be given. Second, the PMMA beads must eventually be removed surgically, resulting in further trauma to the patient's body. Third, PMMA beads do not facilitate new bone formation. As an alternative to the PMMA beads, antibiotics have been mixed with a PMMA bone cement. However, this system also has the limitations which result from the use of a nonabsorbable biomaterial.
Fracture fixation devices, which can contain and release antibiotics, were first described in the late 1980's. For instance, U.S. Pat. No. 4,610,692 describes a method of producing sintered tricalcium phosphate implants for filling bone cavities and for fixing bone fragments in a living body, which comprises:
mixing tricalcium phosphate with at least one substance which forms a gas a high temperatures,
shaping the thus-formed mixture into shaped bodies,
baking the shaped bodies at a temperature sufficiently high to cause gas formation from said substance, thereby forming pores in said shaped bodies,
impregnating said shaped porous bodies with a therapeutically-active ingredient, thereby distributing the same in the pores, and
coating at least a portion of one of said shaped, porous bodies having said therapeutically-active ingredient distributed therein, with a coating of a predetermined thickness of a biodegradable substance,
whereby the time of absorption of said therepeutically-active ingredient is controlled by the thickness of said biodegradable substance.
However, such sintered ceramic bodies are brittle and mechanically weak, which is a disadvantage when such materials are used to manufacture implants for the fixation of bone fragments. Additionally, the biodegradable coating on the porous body prevents bone growth into the pores of the tricalcium phosphate body. Therefore, there is not an advantageous synergism caused by the simultaneous release of antibiotic and the growth of bone tissue. Also, the therapeutically-active ingredient (like antibiotic) is not mixed with a bioabsorbable matrix, but rather is distributed among the pores within the tricalcium phosphate body.
FI 83729 describes bioabsorbable bone fracture fixation implants (external fixator pins and half-pins) and their coatings, which are manufactured of a bioabsorbable polymer, copolymer, polymer alloy or composite, which pin or coating includes an antibiotic or antibiotic mixture which is released from the surface of pin or coating.
PCT/FI 88/00108 describes absorbable, self-reinforced polymeric materials and absorbable fixation devices for the fixation of various tissues or parts of tissues to each other by techniques of internal fixation or external fixation. Typical devices described are rods, plates, screws, nails, intramedullary rods, clamps, cramps etc., which can be applied in internal and/or external fixation of bone fractures, osteotomies, arthrodeses, joint damages and/or of cartilage tissue. Also disclosed are staples, clamps, plates, cramps and corresponding devices, which can be applied in the fixation of soft tissues, fasciae, organs, etc. to each other. It is disclosed that these materials can contain different additives, like antibiotics.
U.S. Pat. No. 4,853,225 describes a method of combating an infection in a patient, where a medicament depot is implanted in the patient, the medicament depot consisting of a physiologically acceptable excipient, which achieves delayed release of at least one chemotherapeutic gyrase inhibitor as the active agent. However, synthetic bioabsorbable polymers are not used as the drug-releasing matrix (excipient), but rather as bioabsorbable binders of collagen, which as a material of biological origin has aroused concern of risks of microbial contamination. Also, this patent does not describe antibacterial bioactive glasses as a component of the excipient to promote bone growth.
PCT/FI 90/00113 describes polymeric, self-reinforced, absorbable surgical materials and/or implants, which can be implanted into or onto tissue, e.g., to repair tissue damage, to join tissues or their parts to each other, to augment tissues or their parts, to separate tissues or their parts from each other and/or from their surroundings, and/or to conduct material between tissues or their parts and/or out of tissues or from the outside into the tissues, where the reinforcing elements are wound at least partially around some axis penetrating the implant. It is also disclosed that these devices can contain some antibiotic.
PCT/FI 89/00236 describes a polymeric (absorbable or biostable) multilayer plate for the fixation of bone fractures, osteotomies, arthrodeses, or for the fixation of a ligament,
Aro Hannu
Koort Jyri
Suokas Esa
Törmäla Pertti
Bioasborbable Concepts, Ltd.
Fubara Blessing
Kenyon & Kenyon
Spear James M.
LandOfFree
Bioabsorbable drug delivery system for local treatment and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bioabsorbable drug delivery system for local treatment and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bioabsorbable drug delivery system for local treatment and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3099204