Short duration depot formulations
Methods and compositions for systemically or locally administering by implantation a beneficial agent to a subject are described, and include, for example, depot gel compositions that can be injected into a desired location and which can provide controlled release of a beneficial agent over a short duration of time. The compositions include a low molecular weight biocompatible polymer, a biocompatible solvent having low water miscibility that forms a viscous gel with the polymer and limits water uptake by the implant, and a beneficial agent.
1. A sustained release dosage form of an anesthetic, said dosage form comprising:
a short duration gel vehicle comprising a low molecular weight bioerodible, biocompatible polymer and a water-immiscible solvent in an amount effective to plasticize the polymer and form a gel therewith; and
an anesthetic dissolved or dispersed in the gel vehicle, wherein said polymer is a lactic acid-based polymer having a weight average molecular weight from about 3,000 to about 10,000, said solvent is benzyl alcohol, and said anesthetic is bupivacaine, and further wherein the dosage form provides for a reduced initial burst of the anesthetic from the dosage form after local administration.
2. The sustained release dosage form of claim 1 , wherein the sustained release occurs in a period of less than or equal to about seven days.
3. The sustained release dosage form of claim 2 , wherein the sustained release lasts for a period of between about 24 hours to about seven days.
4. The sustained release dosage form of claim 2 , wherein the sustained release lasts for a period of about three days.
5. The sustained release dosage form of claim 1 , wherein the polymer comprises a copolymer of lactic acid and glycolic acid (PLGA).
6. The sustained release dosage form of claim 5 , wherein the copolymer has a monomer ratio of lactic acid to glycolic acid of approximately 50:50.
7. The sustained release dosage form of claim 1 , wherein the polymer has a weight average molecular weight of between about 3,000 and about 8,000.
8. The sustained release dosage form of claim 1 , wherein the dosage form comprises from about 1% to about 30% anesthetic by weight.
9. The sustained release dosage form of claim 1 , wherein the anesthetic comprises particles having an average particle size of less than about 250 μm.
10. The sustained release dosage form of claim 1 , wherein the anesthetic comprises particles of bupivacaine base.