Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
2001-03-30
2001-12-11
Reamer, James H (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
Reexamination Certificate
active
06329398
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to analgesia and more specifically to preemptive analgesia used as an adjunct to reduce perioperative pain and methods of using the analgesia.
BACKGROUND OF THE INVENTION
It is known that perioperative pain may be reduced by beginning pain reduction therapy before surgery. This early intervention therapy is commonly known as preemptive analgesia, the purpose of which is to reduce the hypersensitization of nociceptors by blocking pain impulses from ever reaching the brain. Essentially, preemptive analgesia prevents the activation of the nociceptors before activation can occur.
Preemptive analgesia has received widespread acceptance as an adjunct to reduce perioperative pain in patients who undergo surgical procedures as generally disclosed by Mayer et al. in U.S. Pat. No. 5,502,058. The technique is well accepted and involves the pharmacological interruption of afferent neurons to the dorsal horns of the spinal cord prior to the delivery of painful stimuli, such as a surgical incision. The anesthetic concept can be applied to most surgical procedures, minimizing postoperative pain as well as the necessity for narcotic or parenteral analgesia. Moreover, patients treated with preemptive analgesia have experienced reduced hospitalizations and a much shorter convalescence.
A clinical shortcoming of preemptive analgesia, however, has been the relatively short duration of the local anesthetic, lidocaine hydrochloride (HCl), which is considered standard and customary. Lidocaine has a very short half-life (less than 30 minutes) and has no inherent contribution to pain control once its local anesthetic effect has resolved. However, lidocaine HCL's extremely rapid onset of action (less than one minute) characterizes it as an attractive agent for neural blockade.
SUMMARY OF THE INVENTION
It is therefore a primary object of this invention to provide an preemptive analgesic agent, and methods of use, that will maintain the clinical benefits of a fast acting analgesic, and yet provide the additional benefits of longer acting regional anesthetics.
It is a further object of the invention to provide an analgesic agent, and methods of use, that will provide a complete neural blockade throughout the surgical procedure and will contribute to the local anesthetic effect for an extended period after the infiltration.
A preferred formulation of the pharmacological agent of the invention for use as preemptive analgesia, comprises: a solution comprising 1% lidocaine HCL and 0.25% bupivacaine HCL in a ratio of less than or equal to 10:1. Other optimal ratios are less than or equal to 5:1; less than or equal to 2:1 and less than or equal to 1:1. The solution preferably further comprises: one or more buffers selected from a group consisting of sodium hydroxide and hydrochloric acid; and a vasoconstrictor such as epinephrine bitartrate in a ratio of about 1:200,000.
The agent is preferably an injectable therapy adapted for one or more applications selected from a group consisting of subcutaneous, caudal, epidural, intramuscular, intradural, intraspinous and peripheral nerve blockade; and/or preferably is capable of providing analgesic effect for at least six hours.
A more specific preferred formulation of the agent of the invention is an injectable preemptive analgesic agent, comprising, 1% lidocaine HCL and 0.25% bupivicaine in an effective ratio capable of providing at least six hours of analgesic therapy, one or more pH buffers, and one or more vasoconstrictors.
The preferred method of the invention for reducing perioperative pain, generally comprises the steps of: providing a sterile, isotonic pharmacologic agent comprising lidocaine and bupivicaine in a ratio less than or equal to 10:1; and introducing said agent as an adjunct for preemptive analgesia before a surgical procedure is initiated. The agent is best introduced as one or more injectable therapies selected from a group consisting of subcutaneous, caudal, epidural, intramuscular, intradural, intraspinous or peripheral nerve blockade. The agent may comprise 1% lidocaine HCL and 0.25% bupivacaine HCL in a ratio sufficient to provide at least six hours of analgesic effect, and may further comprise a vasoconstrictor such as epinephrine bitartrate and/or one or more buffering compounds such as sodium hydroxide and/or hydrochloric acid.
A more specific variation of the method of the invention for reducing perioperative pain, comprises the steps of, providing a sterile, isotonic pharmacologic agent comprising 1% lidocaine, 0.25% bupivicaine and one or more pH buffers; and infiltrating said agent as an adjunct for preemptive analgesia before a surgical procedure is initiated, whereby said agent provides at least six hours of analgesic effect after infiltration.
REFERENCES:
patent: 4562060 (1985-12-01), Broberg et al.
patent: 5502058 (1996-03-01), Mayer et al.
patent: 5849334 (1998-12-01), Rivlin
patent: 5993836 (1999-11-01), Castillo
patent: 6075059 (2000-06-01), Reader
Mirick, O'Connell, DeMallie & Lougee,
Reamer James H
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