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1. WO1997049391 - METHODS FOR PROVIDING SAFE LOCAL ANESTHESIA

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[ EN ]
What is claimed is:
1. A method for providing substantially safer local anesthesia at a site in a patient, comprising:
administering at a site in a patient in need thereof a biocompatible, biodegradable, controlled release formulation comprising a local anesthetic, said local anesthetic being present in a concentration effective to induce a localized condition selected from the group consisting of sensory anesthesia, motor anesthesia and combinations thereof, and said formulation providing a local anesthesia having substantially improved safety but no prolonged effect relative to a formulation providing a pharmaceutically equivalent dose of local anesthetic in immediate release form.

2 The method of claim 1, wherein at least a portion of said local anesthetic is in immediate release form.

3. The method of claim 1, wherein said controlled release formulation is a plurality of controlled release microspheres suspended in a pharmaceutically acceptable medium for injection, and said method comprises injecting a pharmaceutically effective dose of said microspheres at the site.

4. The method of claim 1, wherein said step of administering said formulation comprises injecting or implanting said formulation in proximity to a nerve to be anesthetized.

5. The method of claim 3 wherein the local anesthetic is incorporated into said plurality of controlled release microspheres at a percent loading of 0.1% to 90% by weight.

6. The method of claim 3 wherein the local anesthetic is incorporated into said plurality of controlled release microspheres at a percent loading from about 70% to about 75% by weight.

7 The method of claim 1 wherein the local anesthetic is selected from the group consisting of bupivacaine, ropivacaine, dibucaine, procaine, chloroprocaine, prilocaine, mepivacaine, etidocaine, tetracaine, lidocaine and xylocaine, and salts, derivatives or mixtures thereof

8 The method of claim 7 wherein the local anesthetic is bupivacaine

9 The method of claim 8 wherein the local anesthetic is bupivacaine HCI

10 The method of claim 8 wherein the local anesthetic is bupivacaine free base

1 1 The method of claim 7 wherein the local anesthetic is ropivacaine

12 The method of claim 8 wherein the bupivacaine is administered in a dose ranging from 5 through 450 mg/kg of a patient

13 The method of claim 1 wherein an amount of the local anesthetic incorporated in a biocompatible, biodegradable, controlled release formulation that is effective to provide local nerve blockade will, when injected into the patient intravenously, fail to induce a toxic reaction

14 The method of claim 13 wherein the local anesthetic is bupivacaine and the intravenously administered dose of the biocompatible, biodegradable, controlled release formulation results in a bupivacaine blood plasma level of less than 1600 ng/ml in the patient

15 The method of claim 13 wherein the local anesthetic is bupivacaine and the intravenously administered dose of the biocompatible, biodegradable, controlled release formulation results in a bupivacaine blood plasma level of less than 1200 ng/ml in the patient 16 The method of claim 13 wherein the local anesthetic is bupivacaine and the intravenously administered dose of the biocompatible, biodegradable, controlled release formulation is unable to produce a bupivacaine blood plasma level of higher than from about 200 to about 650 ng/ml in the patient

17 A method for providing safe regional local anesthesia at a site in a patient, comprising
preparing a local anesthetic in a biocompatible, biodegradable controlled release form such that the percent release of said local anesthetic in vitro is from about 10 to about 60 percent release after 24 hours, from about 20 to about 80 percent after 48 hours, and from about 40 to about 100 percent release after 72 hours,
administering an affective amount of said local anesthetic in a controlled release formulation at a site in a patient in need thereof to provide a reversible local anesthesia at the site, which controlled release formulation has a substantially greater margin of safety but no prolonged effect relative to an immediate release formulation of said local anesthetic which provides a substantially equivalent local anesthetic effect

18 The method of claim 17, wherein said local anesthetic is injected into the patient intravenously

19 The method of claim 17 wherein the local anesthetic is bupivacaine

20 The method of claim 17 wherein the local anesthetic is ropivacaine