Local Anesthetic Microencapsulation.
Abstract
Etidocaine-HCl-polymer core particles have been microencapsulated. Most of the product is in the anticipated 100-400 micron size range. Release rates vary from 50% release in one hour (75-105 micron, 10% coating) to only about 40% release in one day (150-425 micron, 30% coating). Selected materials were evaluated for stability to various storage conditions and for bulk density and pore distribution. In vivo studies included determination of anesthesia of the peripheral nerves of guinea pigs. Circulating levels of anesthetics were measured after injection of solution and microcapsular suspensions in rabbits. Sciatic nerve blocks were short when using slow-releasing etidocaine-HCl microcapsules. However, when using a high concentration (8% drug) of faster releasing microcapsules, many hours of nerve block were observed. Although the results were variable, individual blocks lasted as long as 2 and 4 days. Circulating levels of lidocaine were measured after I.M. injection of soluble and microencapsulated drug in rabbits. Almost no circulating lidocaine was found after injection of lidocaine (base) microcapsules. For lidocaine-HCl, the solution showed peak levels at 10 minutes of 5.6 micrograms/ml; whereas for the same quantity of encapsulated drug the peak occurred at 1 hour and was only 0.9 micrograms/ml. Blood levels of CPK were also significantly lower when microencapsulated drug was injected. This is indicative of less local tissue damage.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 18, 1983
- Accession Number
- ADA149098
Entities
People
- D. E. Creeden
- D. L. Williams
- S. A. Odell
- W. A. Nucefora